ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Column liquid chromatography  (867)
  • phosphorus  (514)
  • Turbulence
  • Springer  (1,462)
  • Annual Reviews
  • Blackwell Publishing Ltd
  • 2020-2024
  • 2005-2009  (2)
  • 1995-1999  (652)
  • 1990-1994  (715)
  • 1980-1984  (93)
Collection
Keywords
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Stochastic environmental research and risk assessment 11 (1997), S. 193-210 
    ISSN: 1436-3259
    Keywords: Turbulence ; sediment ; fluvial ; river ; bursting process ; statistics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Entrainment of sediment particles from channel beds into the channel flow is influenced by the characteristics of the flow turbulence which produces stochastic shear stress fluctuations at the bed. Recent studies of the structure of turbulent flow has recognized the importance of bursting processes as important mechanisms for the transfer of momentum into the laminar boundary layer. Of these processes, the sweep event has been recognized as the most important bursting event for entrainment of sediment particles as it imposes forces in the direction of the flow resulting in movement of particles by rolling, sliding and occasionally saltating. Similarly, the ejection event has been recognized as important for sediment transport since these events maintain the sediment particles in suspension. In this study, the characteristics of bursting processes and, in particular, the sweep event were investigated in a flume with a rough bed. The instantaneous velocity fluctuations of the flow were measured in two-dimensions using a small electromagnetic velocity meter and the turbulent shear stresses were determined from these velocity fluctuations. It was found that the shear stress applied to the sediment particles on the bed resulting from sweep events depends on the magnitude of the turbulent shear stress and its probability distribution. A statistical analysis of the experimental data was undertaken and it was found necessary to apply a Box-Cox transformation to transform the data into a normally distributed sample. This enabled determination of the mean shear stress, angle of action and standard error of estimate for sweep and ejection events. These instantaneous shear stresses were found to be greater than the mean flow shear stress and for the sweep event to be approximately 40 percent greater near the channel bed. Results from this analysis suggest that the critical shear stress determined from Shield's diagram is not sufficient to predict the initiation of motion due to its use of the temporal mean shear stress. It is suggested that initiation of particle motion, but not continuous motion, can occur earlier than suggested by Shield's diagram due to the higher shear stresses imposed on the particles by the stochastic shear stresses resulting from turbulence within the flow.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 29 (1999), S. 1171-1176 
    ISSN: 1572-8838
    Keywords: alloys ; cyclic voltammetry ; electrodeposition ; electroless deposition ; nickel ; phosphorus ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electroless Ni–Zn–P alloy deposition from a sulphate bath, containing sodium hypophosphite as reducer, was investigated. To increase the plating rate, the deposition parameters were optimized. The effect of process parameters (T, pH and [Zn2+]) on the plating rate and deposit composition was examined and it was found that the presence of zinc in the bath has an inhibitory effect on the alloy deposition. As a consequence, the percentage of zinc in the electroless Ni–Zn–P alloys never reaches high values. Using cyclic voltammetry the electrodeposition mechanism of Ni–Zn–P alloys was investigated. It was observed that the zinc deposition inhibits the nickel discharge and, as a consequence, its catalytic activity on hypophosphite oxidation. It was also found that increase in temperature or pH leads to the deposition of nickel rich alloys.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1572-8854
    Keywords: Octahedral ; phosphorus ; chloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound [P(tpp)Cl2]+Cl− crystallizes in the space group P21/n witha=10.701(2),b=24.860(2),c=14.799(2), β=94.24(2)°,Z=4. The phosphorus atom has an octahedral coordination geometry formed by the four nitrogen atoms (Np) of the porphyrinato group and the two chloride ions. The average phosphorus-chloride distance is 2.150(1) Å, with phosphorus situated 0.006 Å below the porphyrin ring.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 27 (1997), S. 1198-1206 
    ISSN: 1572-8838
    Keywords: alloy ; amorphous ; anomalous ; hydrogen ; iron ; nickel ; phosphorus ; plating
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this study we have investigated the electrodeposition of amorphous iron–nickel–phosphorus alloys from a sulfate electrolyte. Fe-Ni alloys are known to exhibit an ’anomalous‘ type of plating behaviour in which deposition of the less noble metal is favoured. We have found that the codeposition of phosphorus from hypophosphite in the electrolyte led to a reversal to a ’normal‘ behaviour. This reversal was due both to the suppression of iron and enhancement of nickel partial currents. The overall deposition process is dominated by the hydrogen evolution reaction. This is exacerbated by the low pH needed to codeposit sufficient phosphorus to achieve an amorphous structure.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1572-8838
    Keywords: alloys ; electroless ; microstructure ; morphology ; nickel ; phosphorus ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electroless Ni–Zn–P alloy coatings were obtained on an iron substrate from a sulfate bath at various pH values. The effects of changes in bath pH on alloy composition, morphology, microstructure and corrosion resistance were studied. Scanning electron microscopy was performed to observe the morphological change of the deposits with bath pH. Coating crystallinity was investigated by grazing incidence asymmetric Bragg X-ray diffraction and transmission electron microscopy. A transition from an amorphous to polycrystalline structure was observed on increasing the bath alkalinity, and thus decreasing the phosphorus content of the alloys. A single crystalline phase corresponding to face-centred-cubic nickel was identified in the alloys obtained from a strong alkaline solution. An increase in zinc percentage up to 23% in the deposits does not change the f.c.c. nickel crystalline structure. Corrosion potential and polarization resistance measurements indicated that the corrosion resistance of electroless Ni–Zn–P alloys depends strongly on the microstructure and chemical composition. The deposits obtained at pH 9.0–9.5 and with 11.4–12.5% zinc and 11.8–11.2% phosphorous exhibited the best corrosion resistance.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1572-879X
    Keywords: selective catalytic reduction ; nitric oxide reduction ; phosphorus ; acid property
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract To examine the influence of phosphorus on the commercial V2O5(WO3)/TiO2 SCR catalyst, measurements were carried out by means of infrared and Raman spectroscopy, XPS, and NO reduction measurement as a function of phosphorus loading. Phosphorus added to the catalyst was found to disperse well over the catalyst without a significant agglomeration up to 5 wt% P2O5 addition. The number of the hydroxyl groups bonded to the vanadium and titanium species decreased readily with increasing amount of phosphorus. Correspondingly, the hydroxyl groups bonded to the phosphorus species were formed. NH3 adsorbed on both hydroxyl groups bonded to vanadium and phosphorus as ammonium ions, implying that the P–OH groups formed are also responsible for the Brønsted acidity. The NO reduction activity was found to be decreased with increasing amount of phosphorus; however, the influence of phosphorus was relatively small irrespective of the large amount of phosphorus addition. The deactivation might be caused by the change in the nature of the surface hydroxyl groups as Brønsted acid sites. Phosphorus species might partially wrap the surface V=O and W=O groups, which might also contribute to the deactivation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 243 (1996), S. 23-28 
    ISSN: 1572-946X
    Keywords: Interplanetary Plasma ; Shock Waves ; Turbulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Effect of turbulence on interplanetary shock waves propagation is considered. It is shown that background turbulence results in the additional shock wave deceleration which may be comparable with the deceleration due to plasma sweeping. The turbulent deceleration is connected with the energy losses due to the strong turbulence amplification behind the moving shock front.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic sciences 53 (1991), S. 263-272 
    ISSN: 1420-9055
    Keywords: Lake ecosystem ; chl-a ; phosphorus ; nitrogen ; river flow ; thermocline ; simulation model ; multiple regression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The management variables which primarily affect phytoplankton biomass (as chl-a) in Lake Mjøsa, Norway, are total phosphorus loading (TP) and the timing and volume of water through flow (by active storage reservoirs). The response of the lake to changes in these factors is studied using a simulation model of the lake ecosystem. Chl-a responses from both observed data and the simulated results are extracted by multiple regression. Results show that decreasing TP load decreases chl-a, but less at low TP levels (〈 10 mg TP · m−3). There is also a certain time period for peak river flow which gives the least yield of chl-a per unit TP. This time period occurs in early summer (i.e., around June 10) if the total phosphorus load is low, and later if the load is high. Both observations and simulation results show that a high water flow increases chl-a at low epilimnion depths (〈 15 m), but that the same high water flow decreases chl-a when epilmnion is deep.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic sciences 52 (1990), S. 199-220 
    ISSN: 1420-9055
    Keywords: Eutrophication ; lake management ; phosphorus ; ecosystem ; chlorophyll-a ; mathematical modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We compare results of a new model for predicting the short term inter annual changes in chlorophyll-a (chl-a) in lakes after reductions in total phosphorus (TP) to predictions made by least squares regression models. In the new method, slopes of chl-a/TP graphs (both axes in mg · m−3) are depicted in frequency diagrams and used to extract information on the expected, short term chl-a/TP response. The short term response for nine shallow (〈 10 m deep) and nutrient rich lakes to changes in TP was found to be: Chl-a = 0.49 · TP + 17.3, and for nine deep, P-limited lakes: Chl-a = 0.08 · TP + 3.5. If the TP-reduction is known to be greater than 10 mg · m−3, the expected slope increases to 0.58 for shallow lakes and to 0.26 for deep lakes. The slope, 0.58, is 8% lower than the slope for the long term response calculated by regression for the shallow lakes. For deep lakes the slope, 0.26, is 2 to 3 times higher than that calculated by regression, indicating that reductions in TP for deep lakes give greater effects than least squares regression equations suggest. We have also calculated the reduction in TP which will give about 80% probability that a reduction in chl-a will be observed next year. For shallow, P-limited lakes this reduction is about 30 mg · m−3 (5% of average initial in-lake TP concentration), and for deep lakes about 14 mg · m−3 (35% of average initial in-lake TP concentration).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic sciences 52 (1990), S. 256-268 
    ISSN: 1420-9055
    Keywords: Vertical mixing ; stratification ; phosphorus ; Lake Constance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Depth variable vertical eddy diffusion coefficients for heat (K z) were calculated from continuously measured temperature profiles in Überlinger See (western part of Lake Constance). The temperatures were averaged over vertical intervals of 10 m yielding 14 discrete values (maximum depth of Überlinger See: 147 m). A linear fit from 10 June to 29 September 1987 was used to smooth the significant temperature fluctuations caused by internal seiches of Lake Constance. Assuming horizontal homogeneity for the smoothed data the Gradient-Flux-Method was applied to compute vertical diffusion coefficientsK z at different depths using the depth variable volumes and surfaces of the 14 layers. The resulting mean diffusion coefficients for the period from June to September are 0.04 cm2/s near the thermocline and up to 0.8 cm2/s in deeper strata (accuracy: ± 50%). It is shown that horizontal mixing between Überlinger See and Obersee (main lake) alters the computation ofK z by less than 50%. A relationship betweenK z and stability (Brunt-Väisälä) frequencyN is found which corresponds well to the theory of internal wave induced turbulence. Combining the diffusion coefficients with measured phosphorus profiles, a phosphorus flux from the hypolimnion to the epilimnion of (0.7 ± 0.4) mg P m−2 d−1 was calculated, corresponding to about 20% of the average external loading per area of Lake Constance in 1986.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    ISSN: 1420-9055
    Keywords: Sediment ; interstitial water ; phosphorus ; iron ; persulfate digestion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It is shown that sorption of orthophosphate to iron compounds, formed during persulfate digestion, can cause a significant underestimation of total dissolved phosphorus in interstitial waters rich in iron and poor in phosphorus. Labelling the samples with carrier free32PO4 before digestion allows to correct for these losses.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    ISSN: 1432-0789
    Keywords: Key words Phosphorus dynamics ; Olsen ; phosphorus ; Soil phosphorus fractions ; Manure ; Soybean-wheat rotation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Soil P availability and efficiency of applied P may be improved through an understanding of soil P dynamics in relation to management practices in a cropping system. Our objectives in this study were to evaluate changes in plant-available (Olsen) P and in different inorganic P (Pi) and organic P (P0) fractions in soil as related to repeated additions of manure and fertilizer P under a soybean-wheat rotation. A field experiment on a Typic Haplustert was conducted from 1992 to 1995 wherein the annual treatments included four rates of fertilizer P (0, 11, 22 and 44 kg ha–1 applied to both soybean and wheat) in the absence and presence of 16 t ha–1 of manure (applied to soybean only). With regular application of fertilizer P to each crop the level of Olsen P increased significantly and linearly through the years in both manured and unmanured plots. The mean P balance required to raise Olsen P by 1 mg kg–1 was 17.9 kg ha–1 of fertilizer P in unmanured plots and 5.6 kg ha–1 of manure plus fertilizer P in manured plots. The relative sizes of labile [NaHCO3-extractable Pi (NaHCO3-Pi) and NaHCO3-extractable P0 (NaHCO3-P0)], moderately labile [NaOH-extractable Pi (NaOH-Pi) and NaOH-extractable P0 (NaOH-P0)] and stable [HCl-extractable P (HCl-P) and H2SO4/H2O2-extractable P (resisual-P)] P pools were in a 1 : 2.9 : 7.6 ratio. Application of fertilizer P and manure significantly increased NaHCO3-Pi and -P0 and NaOH-Pi, and -P0 fractions and also total P. However, HCl-P and residual-P were not affected. The changes in NaHCO3-Pi, NaOH-Pi and NaOH-P0 fractions were significantly correlated with the apparent P balance and were thought to represent biologically dynamic soil P and act as major sources and sinks of plant-available P.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    ISSN: 1436-5073
    Keywords: aluminium oxide ; phosphorus ; XRF ; RBS ; FTIR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Phosphorus-doped aluminium oxide thin films were deposited in a flow-type ALE reactor from AlCl3, H2O and from either P2O5 or trimethyl-phosphate. Structural information of the films was obtained from Fourier transform infrared (FTIR) spectra. Rutherford backscattering spectroscopy (RBS) was used to quantitatively determine the composition of the films. The P/Al intensity ratios calculated from X-ray fluorescence (XRF) results were in a linear relation with the P/Al concentration ratios calculated from RBS results. For comparison, the intensity ratios of the phosphorus peak (P=O) at about 1250 cm−1 and the aluminium peak (Al-O) at about 950 cm−1 were determined from the IR absorption spectra. The calibration of FTIR peak intensities was done by plotting the intensity ratios of phosphorus and aluminium peaks against the P/Al concentration ratios measured by RBS. FTIR gave also a linear calibration curve with RBS but the method is less suitable for routine analysis of P/Al ratio than XRF.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Microchimica acta 101 (1990), S. 273-279 
    ISSN: 1436-5073
    Keywords: aluminium analysis ; phosphorus ; sulfur ; chlorine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Multi-step procedures for the determination of phosphorus, sulfur and chlorine are described and tested against established methods and on reference materials. Phosphorus is separated as hydrogen phosphide, extracted as phosphomolybdic acid, reduced to molydenum blue and measured photometrically (detection limit 0.05 μg/g). Sulfur is separated after reduction as hydrogen sulfide or by means of pyrohydrolysis and measured by ICP-OES (detection limit 0.1 μg/g). Chloride can be measured by ion chromatography after pyrohydrolytic separation (detection limit 0.1 μg/g). The determination of sulfur was also successfully tested on copper and steel samples.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Microchimica acta 109 (1992), S. 201-209 
    ISSN: 1436-5073
    Keywords: phosphonate base scale inhibitor ; brine ; direct current plasma ; inductively coupled plasma atomic emission spectrometry ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The determination of phosphonate base scale inhibitors in brines by direct current plasma (DCP) and inductively coupled plasma atomic emission spectrometry (ICP-AES) is described. The first method is based on a direct nebulization of the brine samples and plasma using the phosphorus line at 213.618 nm. The second method involves extraction of phosphorus as phospho-antimonyl molybdate complex into methylisobutyl ketone (MIBK) phase and analysis of the extract for molybdenum using the Mo 313.260 nm line. Comparison between the proposed methods and an established recommended method [1] shows excellent agreement between the results in addition to the sensitivity and ease of automation provided by AES.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Meccanica 33 (1998), S. 445-468 
    ISSN: 1572-9648
    Keywords: Turbulence ; Wall-bounded turbulent shear flows ; Scaling laws in turbulence ; Local structure of turbulence ; Fluid mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Turbulence at very large Reynolds numbers (often called developed turbulence) is widely considered to be one of the happier provinces of the turbulence realm, as it is widely thought that two of its basic results are well-established, and have a chance to enter, basically untouched, into a future complete theory of turbulence. These results are the von Kármán-Prandtl universal logarithmic law in the wall-region of wall-bounded turbulent shear flow, and the Kolmogorov-Obukhov scaling laws for the local structure of developed turbulent flow.However, doubts have been expressed over the years about the fluid mechanical assumptions that underlie these laws. After a concise review of the problem of turbulence as a whole we will show in the present paper that the von Kármán–Prandtl universal logarithmic law is based on an assumption which,though plausible, in fact is not quite correct. We will come to the conclusion, based on theoretical considerations and on processing of experimental data, that the universal logarithmic law does not describe the real features of developed turbulent wall-bounded flow of viscous fluid; it should be jettisoned and replaced by a different law, a scaling law. Experimental evidence for the local structure of turbulent flows is now not sufficiently well-established to allow a similarly definite conclusion. However, the application of the new approach presented here makes it very plausible that the classical, non-modified version of Kolmogorov–Obukhov ‘K-41’ laws gives an adequate description of the local features of developedturbulent flows. Sommario.La turbolenza agli altissimi numeri di Reynolds (spesso chiamata turbolenza sviluppata) è largamente ritenuta una delle regioni felici del regno della turbolenza: si pensa infatti che due suoi risultati fondamentali siano ben assodati e che abbiano speranza di entrare senza rilevanti modifiche in una futura teoria completa della turbolenza.Questi risultati sono la legge logaritmica universale di Kármán–Prandtl per la regione di parete dei flussi turbolenti confinati e la legge di simulitudine di Kolmogorov–Obukhov per la struttura locale del flusso turbolento sviluppato. Nel corso degli anni sono stati tuttavia espressi dubbi sulle ipotesi fluidodinamiche che sottendono queste leggi. Nel presente lavoro, dopo un breve esame del problema della turbolenza nel suo insieme,dimostreremo che la legge logaritmica universale di Kármán–Prandtl è basata su un'assunzione che, per quanto plausibile, non è del tutto corretta. Giungeremo alla conclusione, basata su considerazioni teoriche esull'elaborazione di dati sperimentali, che la legge logaritmica universale non descrive le caratteristiche reali del flusso turbolento di un fluido viscoso sviluppato e confinato da una parete; essa dovrebbe essere sostituita de una legge differente, una legge di similitude. L'evidenza sperimentale per la stzuttura locale di flusso turbolento non è al momento sufficientemente assodata perpermettere una conclusione altrettanto definita. L'impiegodel nuovo approccio qui presentato, tuttavia, rende assai plausible che la classica versione non modificata della legge ‘K-41’ di Kolmogorov-Obukhov fornisca una adeguata descrizione delle caratteristiche locali del flussoturbolento sviluppato.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Meccanica 33 (1998), S. 29-46 
    ISSN: 1572-9648
    Keywords: Finite difference methods ; Free shear layers ; Turbulence ; Fluid mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A computational formulation is proposed for second-moment closure turbulence models, especially suited to models intended to ensure physical realizability. It enables to cast the quite complicated model equations in a compact form. It is specifically applied here to a two-dimensional parabolized flow, though it lends itself to extension to more complex flows. An effective computational algorithm is proposed, based on a staggered grid and a block tridiagonal solver. The algorithm is applied to a turbulent mixing layer, and the comparison between the predictions obtained by standard modelling tools and a realizable second-moment closure clearly points out the superiority of the latter.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Meccanica 33 (1998), S. 503-516 
    ISSN: 1572-9648
    Keywords: Flow visualization ; Speckle photography ; Particle image velocimetry ; Turbulence ; Fluid mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Modern developments in laser and computer technology, electronic cameras, and digital image processing techniques allow to generate planar distributions of quantitative data in turbulent flows. Large amounts of data can be processed easily and analyzed statistically. With these tools, it is possible to quantitatively visualize turbulent coherent structures, even in flows of high Reynolds number, and measure characteristic spatial quantities like vorticity, length scales, spatial correlation functions, etc. These potentials in analyzing spatial characteristics of turbulent flows are demonstrated with two different methods of quantitative flow visualization: speckle photography as a representative of the line-of-sight methods, and particle image velocimetry belonging to the methods that rely on the scattering of laser light from tracer particles. Sommario.I moderni sviluppi nelle tecnologie del laser e dei computers, delle telecamere elettroniche e le tecniche di analisi digitale delle immagini permettono di ottenere distribuzioni quantitative, in un piano, di dati relativi a flussi turbolenti. Una gran quantità di dati può essere con facilità analizzata statisticamente. Con questi mezzi è possibile visualizzare quantitativamente strutture coerenti turbolente anche in flussi da alto numero di Reynolds, e misurare caratteristiche spaziali, come vorticità scale e funzioni di correlazione. Questa potenzialità di studiare caratteristiche spaziali di flussi turbolenti viene qui mostrata per due differenti metodi di visualizzazione quantitativa: fotografia ‘speckle’ e PIV (particle image velocimetry).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Meccanica 29 (1994), S. 453-464 
    ISSN: 1572-9648
    Keywords: Vortices ; Turbulence ; Intermittency ; Vortex dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Sommario La struttura di regioni ad intensa vorticità in campi di flusso turbolento omogenei, isotropi ed in equilibrio, simulati numericamente, viene studiata per quattro differenti numeri di Reynolds nell'intervalloRe λ=35÷170, e si trova che tali regioni si organizzano in vortici coerenti, cilindrici o a forma di nastro (‘vermi’). Con rifermento ai numeri di Reynolds studiati, si vede che tali vortici sono responsabili per gran parte delle code estreme ed intermittenti, osservate nelle statistiche dei gradienti di velocità, ma la loro importanza sembra decrescere a più altiRe λ. I loro raggi scalano con la microscala di Kolmogorov e le loro lunghezze con la scala integrale del flusso, mentre la loro circolazione cresce monotonicamente conRe λ. Per quest'ultimo riscalamento viene offerta una spiegazione basata sull'assunzione della presenza di onde inerziali assiali lungo i loro nuclei, eccitate da una deformazione di fondo casuale dell'ordine della radice quadrata della velocità media. Questa spiegazione è consistente con la presenza di incrementi paragonabili di allungamenti e compressioni lungo i nuclei dei vortici.
    Notes: Abstract The structure of the intense vorticity regions is studied in numerically simulated homogeneous, isotropic, equilibrium turbulent flow fields at four different Reynolds numbers, in the rangeRe λ=35–170, and is found to be organized in coherent, cylindrical or ribbon-like, vortices (‘worms’). At the Reynolds numbers studied, they are responsible for much of the extreme intermittent tails observed in the statistics of the velocity gradients, but their importance seems to decrease at higherRe λ. Their radii scale with the Kolmogorov microscale and their lengths with the integral scale of the flow, while their circulation increases monotonically withRe λ. An explanation is offered for this latter scaling, based in the assumed presence of axial inertial waves along their cores, excited by a random background strain of the order of the root mean square vorticity. This explanation is consistent with the presence of comparable amounts of stretching and compression along the vortex cores.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Meccanica 30 (1995), S. 719-725 
    ISSN: 1572-9648
    Keywords: Turbulence ; Self-similarity ; Fluid dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Sommario Nel presente lavoro viene presentato uno studio riguardante le proprietà della cosiddetta funzione di forma $$f\left( {\frac{r}{\eta }} \right)$$ che caratterizza le leggi di scala delle fluttuazioni di velocità in un flusso turbolento. L'analisi é basata su precedenti misure sperimentali effettuate in flussi turbolenti generati da griglie a bassi Reλ ed in condizioni omogenee e non omogenee. Le proprietá di universalitá della funzione di forma sono studiate nell'ambito della cosiddetta Extended Self-Similarity.
    Notes: Abstract In this work some investigations on the properties of the so calledform function $$f\left( {\frac{r}{\eta }} \right)$$ which characterizes the scaling behavior of the small scales fluctuations in a turbulent flow are presented. The present analysis is based on previous experimental measurements in homogeneous and non-homogeneous grid-generated turbulence at low Reλ. The universality properties of the form function are investigated in the frame of the Extended Self Similarity (ESS) form of scaling.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    ISSN: 1573-0417
    Keywords: Great Basin ; climatic variations ; productivity ; organic matter ; nitrogen ; phosphorus ; hardwater lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Sediment cores from the shallow and deep basins of Pyramid Lake, Nevada, revealed variations in composition with depth reflecting changes in lake level, river inflow, and lake productivity. Recent sediments from the period of historical record indicate: (1) CaCO3 and organic content of sediment in the shallow basin decrease at lower lake level, (2) CaCO3 content of deep basin sediments increases when lake level decreases rapidly, and (3) the inorganic P content of sediments increases with decreasing lake volume. Variations in sediment composition also indicate several periods for which productivity in Pyramid Lake may have been elevated over the past 1000 years. Our data provide strong evidence for increased productivity during the first half of the 20th Century, although the typical pattern for cultural eutrophication was not observed. The organic content of sediments also suggests periods of increased productivity in the lake prior to the discovery and development of the region by white settlers. Indeed, a broad peak in organic fractions during the 1800's originates as an increase starting around 1600. However, periods of changing organic content of sediments also correspond to periods when inflow to the lake was probably at extremes (e.g. drought or flood) indicating that fluctuations in river inflow may be an important factor affecting sediment composition in Pyramid Lake.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    ISSN: 1573-0417
    Keywords: diatoms ; eutrophication ; lake management ; paleolimnology ; British Columbia ; lakes ; phosphorus ; training sets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Eighteen lakes were added to a published training set of 46 British Columbia (BC) lakes in order to expand the original range of total phosphorus (TP) concentrations. Canonical correspondence analysis (CCA) was used to analyze the relationship between diatom assemblages and environmental variables. Specific conductivity and [TP] each explained significant (P≤0.05) directions of variance in the distribution of the diatoms. The relationship between diatom assemblages and [TP] was sufficiently strong to warrant the development of a weighted-averaging (WA) regression and calibration model that can be used to infer past trophic status from fossil diatom assemblages. The relationship between observed and inferred [TP] was not improved by the addition of more eutrophic lakes, however the [TP] range and the number of taxa used in the transfer function are now superior to the original model. Diatom species assemblages changed very little in lakes with TP concentrations greater than 85 µg 1−1, so we document the development of a model containing lakes with TP≤85 µg 1−1. The updated model uses 59 training lakes and covers a range of species optima from 6 to 41.9 µg 1−1 TP, and a total of 150 diatom taxa. The updated inference model provided a more realistic reconstruction of the anthropogenic history of a highly eutrophic BC lake. The model can now be used to infer past nutrient conditions in other BC lakes in order to assess changes in trophic status.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    Electronic Resource
    Electronic Resource
    Springer
    Journal of paleolimnology 20 (1998), S. 47-55 
    ISSN: 1573-0417
    Keywords: diatoms ; spatial variability ; canonical correspondence analysis ; lake eutrophication ; transfer functions ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Diatom analyses were undertaken of sediment cores covering a range of water depths in a small eutrophic lake (Lough Augher, Co. Tyrone, N. Ireland). The significance of between-core variability in diatom relative frequency stratigraphy was assessed by Canonical Correspondence Analysis (CCA) where the ordination axes were constrained to external environmental variables (sediment depth, core location coordinates, water depth, effective fetch, distance-from-shore and distance-from-inflow). After the removal of the effect of sediment age by partialling it out, the resultant first two axes from the partial-CCA were significantly correlated with water depth and distance-from-shore, indicating non-uniform diatom stratigraphies across the lake. Despite this variability, all cores show the same succession of species and, therefore, record the eutrophication of the lake. Diatom-inferred total phosphorus (DI-TP) was inferred for six cores using weighted averaging regression and calibration. Apart from considerable differences of DI-TP in surficial sediment samples, there was good between-core repeatability of DI-TP profiles. These data support the use of DI-TP for establishing background nutrient concentrations for lakes, and associated implications for lake restoration schemes using single cores. Comparisons of DI-TP profiles and total diatom accumulation rate data for the individual cores indicate that diatom production peaked prior to the maximum TP concentrations in the lake.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    ISSN: 1573-0417
    Keywords: carbon isotopes ; diatoms ; lake management ; nitrogen isotopes ; phosphorus ; radium-226 ; sediments ; trophic state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract We explored the use of carbon and nitrogen isotopes (δ13C and δ15N) in sedimented organic matter (OM) as proxy indicators of trophic state change in Florida lakes. Stable isotope data from four 210Pb-dated sediment cores were compared stratigraphically with established proxies for historical trophic state (diatom-inferred limnetic total phosphorus, sediment C/N ratio) and indicators of cultural disturbance (sediment total P and 226Ra activity). Diatom-based limnetic total P inferences indicate a transition from oligo-mesotrophy to meso-eutrophy in Clear Lake, and from eutrophy to hypereutrophy in Lakes Parker, Hollingsworth and Griffin. In cores from all four lakes, the carbon isotopic signature of accumulated OM generally tracks trophic state inferences and cultural impact assessments based on other variables. Oldest sediments in the records yield lower diatom-inferred total limnetic P concentrations and display relatively low δ13C values. In the Clear, Hollingsworth and Parker records, diatom-inferred nutrient concentrations increase after ca. AD 1900, and are associated stratigraphically with higher δ13C values in sediment OM. In the Lake Griffin core, both proxies display slight increases before ~1900, but highest values occur over the last ~100 years. As Lakes Clear, Hollingsworth and Parker became increasingly nutrient-enriched over the past century, the δ15N of sedimented organic matter decreased. This reflects, in part, the increasing relative contribution of nitrogen-fixing cyanobacteria to sedimented organic matter as primary productivity increased in these waterbodies. The Lake Griffin core displays a narrow range of both δ13C and δ15N values. Despite the complexity of carbon and nitrogen cycles in lakes, stratigraphic agreement between diatom-inferred changes in limnetic total P and the stable isotope signatures of sedimented OM suggests that δ13C and δ15N reflect shifts in historic lake trophic state.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    ISSN: 1573-0417
    Keywords: diatoms ; Everglades ; phosphorus ; wetland ; calibration ; multivariate ; Florida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The relationship between diatom taxa preserved in surface soils and environmental variables at 31 sites in Water Conservation Area 2A (WCA-2A) of the Florida Everglades was explored using multivariate analyses. Surface soils were collected along a phosphorus (P) gradient and analyzed for diatoms, total P, % nitrogen (N), %carbon (C), calcium (Ca), and biogenic silica (BSi). Phosphorus varied from 315-1781 μg g-1, and was not found to be correlated with the other geochemical variables. Canonical correspondence analysis (CCA) was used to examine which environmental variables correlated most closely with the distributions in diatom taxa. Canonical correspondence analysis with forward selection, constrained and partial CCA, and Monte Carlo permutation tests of significance show the most significant changes in diatom assemblages along the P gradient (p 〈 0.01), with additional species differences correlated with soil C, N, Ca, and BSi. Weighted-averaging (WA) regression and calibration models of diatom assemblages to P and BSi were developed. The diatom-based inference model for soil [P] had a high apparent r2 (0.86) with RMSEboot = 218 μg g-1. Indicator diatom species identified by assessing species WA optima and WA tolerance to [P], such as Nitzschia amphibia and N. palea for high [P] (~1300-1400 μ g-1) and Achnanthes minutissima var. scotica and Mastogloia smithii for low [P] (~400-600 μg g-1), may be useful as monitoring tools for eutrophication in WCA-2A as well as other areas of the Everglades. Diatom assemblages analyzed by cluster analysis were related to location within WCA-2A, and dominant taxa within clusters are discussed in relation to the geochemical variables measured as well as hydrology and pH. Diversity of diatom assemblages and a ‘Disturbance Index’ based on diatom data are discussed in relation to the historically P-limited Everglades ecosystem. Diatom assemblages should be very useful for reconstructions of [P] through time in the Florida Everglades, provided diatoms are well preserved in soil cores.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    Electronic Resource
    Electronic Resource
    Springer
    Journal of paleolimnology 20 (1998), S. 31-46 
    ISSN: 1573-0417
    Keywords: phosphorus ; Lake Okeechobee ; lead-210 dating ; eutrophication ; phosphorus loading
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Phosphorus accumulation rates in depositional zone sediments of Lake Okeechobee were determined in 11 mud-zone cores and two peat-zone cores dated by 210Pb. Although difficulties were encountered in interpreting 210Pb data from some sites, reliable dating of sediments from the mud zone of this shallow lake is possible. Sediment accumulation rates in this zone have increased during the present century by an average of about twofold, and accumulation of organic sediments in the lake during pre-settlement times apparently was much slower than during the past century. Concentrations of all forms of sedimentary P but especially nonapatite inorganic-P and organic-P also have increased since pre-settlement times and especially since about 1940. Annual P accumulation rates in the lake's sediments have increased about fourfold during the 1900s, with most of the increase occurring in the past 40–50 years. The recent accumulation rate of sedimentary P (past ~ 10 years) agrees within a factor of 1.5 with the net retention of P in the lake calculated from published input-output mass balances.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 1 (1980), S. 95-101 
    ISSN: 1573-0867
    Keywords: soil fertility ; phosphorus ; potassium ; green manure ; crop rotation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Changes in the soil phosphorus and potassium status on three farming systems in the Northeast Polder during 25 years are related to the fertilizer regime over this period. The changes in the nutrient status of the soil are reflected in fertilizer policy. High rates of phosphate dressings markedly increased the phosphate status of the soil and built up a reserve of phosphate. In contrast, the potassium status decreased by about half, because only potatoes in the rotation were dressed with potassium. Methods of fertilization are discussed and suggestions are made with regard to possible improvements.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 36 (1993), S. 127-133 
    ISSN: 1573-0867
    Keywords: hydrology ; water balance ; phosphorus ; Streamflow ; Peel-Harvey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper discusses the land types, hydrologic characteristics and processes, and the major modification of these, in relation to mechanisms and magnitude of phosphorus losses to drains and riverine systems which discharge to the Peel-Harvey estuary. About 75% of the coastal plain part of the catchment is cleared of native vegetation and used for dryland, dairy and beef grazing. There are small areas devoted to irrigated pasture and commercial horticulture. Seventy-five percent of the soils of the catchment are sandy surfaced with a poor capacity to retain phosphorus. Though the area is flat, catchment water yields are high because of a large winter rainfall excess and low soil storage capacity. Drainage schemes have been constructed in much of the catchment to remove excess water quickly. This was required initially to allow agricultural expansion and is now important for protecting a growing infrastructure which serves the most populous region of Western Australia.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 37 (1994), S. 1-22 
    ISSN: 1573-0867
    Keywords: animal slurries and manures ; applications to soils ; carbon- ; nitrogen- ; phosphorus ; contamination ; crop production ; dissemination ; hazardous organics ; heavy metals ; inputs ; macro- and micronutrients ; pathogens ; sewage sludges ; survival- ; transfer- ; transport and adsorption rates in soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The European Community is producing annually about 300 × 106 tons of sewage sludges as well as about 150, 950,160 and 200 tons of domestic, agricultural, industrial and other wastes (street litter, dead leaves etc.). About 20–25% of the German sewage sludges, which contain in average about 3.8,1.6, 0.4, 0.6, 5.3% DM−1 N, P, K, Mg and Ca, 202, 5, 131, 349, 53, 3 and 1446 mg kg−1 DM Pb, Cd, Cr, Cu, Ni, Hg, Zn as well as ca. 37 and 5 mg kg−1 Dm polychlorinated hydrocarbons and biphenyls, are recycled annually as fertilizer. In addition environmental impacts on the arable land of Germany may derive from 76,19.2, 64.7, 33.6, 7.8 and 0.1 kg ha−1 a−1 of N, P, K, Ca, Mg and Cu added as animal manures. Besides heavy metals and hazardous organics pathogens are disseminated with organic wastes. Crop production and soil fertility generally profit from the considerable amounts of plant nutrients and carbon in sewage sludges, animal slurries and manures, but the physicochemical soil properties, the composition of microbial, faunal and plant communities as well as the metabolic processes in the soil-, rhizo- and phyllosphere are changed by organic manuring. Consequences for the soil carbon-, nitrogen-and phosphorus-cycle are discussed. Impacts of heavy metals and hazardous organics on the soil biomass and its habitat as well as on transport mechanisms and surival times of disseminated pathogens in soils are reviewed with emphasis on the German situation. A proposal for future strategies (landscape recycling) is made.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 27 (1991), S. 107-111 
    ISSN: 1573-0867
    Keywords: Liming ; phosphorus ; heathland ; copper ; fertilization ; forest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Forest fertilization in the Netherlands has played an important role in the phase of afforestation of former heathlands. Research started in the early fifties, but results were not applied in practical forestry. A review is presented on forest fertilization in practice, and on the main results of the activities of De Dorschkamp on NPK fertilization, liming and micronutrients application. Attention is paid to problems which have developed during the past ten years.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 26 (1990), S. 253-269 
    ISSN: 1573-0867
    Keywords: Nitrogen ; phosphorus ; sulphur ; nutrient balances ; surface waters ; North Sea ; Baltic Sea ; eutrophication ; hypertrophication ; primary production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Dissolved inorganic nitrogen and phosphorus, their relationship to each other (DIN/DIP) as predisposing (nutrient) factors, as well as prevailing weather as a triggering factor all work together to induce the primary production and hence the eutrophication (hypertrophication) process in surface waters. Sulfate likewise is a decisive predisposing factor influencing the eutrophication process by reducing N availability but increasing P availability and thus acting towards an N limitation of the primary production. This is one of the reasons why marine (coastal) waters and estuaries often exhibit N limitation with respect to primary production, while freshwater ecosystems often tend to exhibit P limitation. Within the N and P balance of agriculture of some countries of Western Europe (Netherlands, Denmark, Switzerland, FRG, UK and Sweden for N, resp. Netherlands, FRG and GDR for P) more the level than the efficiency of the N and P applications indicates the extent of the nutrient surplus. Despite 59–73% N utilization in plant production, the rate of 13–23% for agriculture as a whole equals to the 12–21% efficiency of N use in animal production. The varying N surplus in agriculture in the separate countries of 124 to 465 kg N ha−1 a−1 is determined almost exclusively by the level of the N application and not by its efficiency. The situation is similar for P: In spite of P utilization in plant production of 59–76%, P utilization in total agriculture is only 11–38%, or comparable to the P efficiency within animal production of 10–34%. The differing P excess balance of 55 to 88 kg P2O5 ha−1 a−1 is influenced by the level of the P application. The N and P efficacy of total agriculture hence is determined almost completely by that of animal production, since 83–95% (N basis) and 76–94% (P basis) of the total plant production (on top of the nationally varying levels of N and P use via imported feeds) are fed to animals — with the low N and P utilization cited above. Agriculture's share of the N and P emissions into surface water of several countries/regions in Western Europe (FRG, Netherlands, Italy, Denmark, Switzerland, Norway) ranges from 37 to 82% resp. 27 to 38%. Its share in the flus into the North Sea catchment basin will be about 60% for N and 25% for P related only to the anthropogenic material carried by the rivers. Agriculture's share in the atmospheric N emissions into the North and Baltic Seas can be estimated at about 65% or 55%, resp. while the remaining approx. 35% or 45%, resp. are traceable primarily to anthropogenic burning processes. For agriculture the priority lies in limiting N emissions into surface water caused by leaching, erosion and NH3 emissions, and reducing P emissions mainly through soil conservation (protection against erosion) and water protection. As regards N this means a demand for comprehensive protection of groundwater and atmosphere differentiated according to the potential for losses or the risk of losses on a site, also outside the protection zones. As regards P only those areas can be included in the demand for reduction of emissions that are actually threatened by erosion or surface runoff. Plenty of short-term and long-term measures are available to agriculture to reduce N and P emissions. Especially the long-range measures (such as creating nutrient balances on farms and fields, the integration of animal and plant production, maintaining maximum livestock densities according to the ability of areas to absorb nutrients, altered feeding programs in animal nutrition, changes in livestock keeping (slurry→deep litter), increasing the internal and external recycling of N and P) are capable of bringing about a satisfactory degree of success within the next 20 to 30 years.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 40 (1994), S. 165-173 
    ISSN: 1573-0867
    Keywords: Animal manure ; eutrophication ; ground water ; nitrogen ; phosphorus ; surface runoff
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract With the rapid growth of the poultry industry in Oklahoma, U.S.A., more litter is applied to farm land. Thus, information is required on the impact of applications on regional soil and water resources. The effect of soil and poultry litter management on nitrogen (N) and phosphorus (P) loss in runoff and subsurface flow from four 16 m2 plots (Ruston fine sandy loam, 6 to 8% slope) was investigated under natural rainfall. Plots under Bermudagrass (Cynodon dactylon) received 11 Mg litter ha−1, which amounts to contributions of approximately 410 kg N and 140 kg P ha−1 yr−1. In spring, litter was broadcast on 3 of the plots; the upper half of one and total area of the other two. One of the total-area broadcast plots was tilled to 6 cm, the other remained as no till. The fourth plot served as a control. Relative to the control, litter application increased mean concentrations of total N and total P in runoff during the 16-week study for no-till (15.4 and 5.8 mg L−1) and tilled treatments (16.7 and 6.1 mg L−1). However, values for the half-area application (5.6 and 2.0 mg L−1) were similar to the control (5.7 and 1.3 mg L−1). Interflow (subsurface lateral flow at 70 cm depth) P was not affected by litter application; however, nitrate-N concentrations increased from 0.6 (control) to 2.9 mg L−1 (no till). In all cases, 〈 2 % litter N and P was lost in runoff and interflow, maintaining acceptable water quality concentrations. Although litter increased grass yield (8518 kg ha−1) compared to the control (3501 kg ha−1), yields were not affected by litter management. An 8-fold increase in the plant available P content of surface soil indicates long-term litter management and application rates will be critical to the environmentally sound use of this nutrient resource.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 41 (1995), S. 167-178 
    ISSN: 1573-0867
    Keywords: phosphorus ; workshop ; environment ; review
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A workshop was held in 1990 in Muscle Shoals, Alabama to discuss current and future research on phosphorus in agriculture. Twenty four presentations were given in areas ranging from basic to applied research. For five of the research areas presented at the workshop, this paper presents a literature review, a review of presentations at the workshop, and a discussion of future research ideas.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 43 (1995), S. 109-115 
    ISSN: 1573-0867
    Keywords: phosphorus ; European network ; maintenance fertilization ; fixation capacity ; comparison of methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract After three years of a research network project on mineral phosphorus fertilization including five experimental fields located in Europe the first results are discussed. Crop response was very significant to TSP application in the alluvial calcareous polder soil of Netherlands, and in the brown silty acid soil of Scotland, both having a low level of P availability and a high fixation capacity. In the alluvial sandy loam on chalk in England, a response was observed to the first fertilization level equal to the previous crop export of phosphorus. In the brown sandy-silty soil on sand in Germany the highest rate of TSP led to a response in the third year. No effect on the final yields was observed in the brown silt loam of Belgium characterised by a textural B horizon with a high P fixation capacity. The critical values for phosphorus fertilization are discussed as the amount of P needed to maintain a target value of soil phosphorus. Concerning the supply of the different soils, no balance was reached in the Dutch and Scottish soils, a steady state was reached in the English soil with the return of the previous crop removal and the critical value for P was lower than the return of the previous crop export in the German and Belgian soils. According to the eight methods of P determination compared in the network, the P contents in the plow layer were raised in the soils of Netherlands, England and Scotland. They remained at the same level or fluctuated depending on the soil testing methods in Germany and in Belgium. High correlations exist between the different methods used in routine analysis, except for the calcium cloride and calcium acetate lactate method. Annual fluctuations in the soil P were detected at different depths depending on analytical methods and need further research.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 43 (1995), S. 131-136 
    ISSN: 1573-0867
    Keywords: phosphorus ; titanium ; fertilizer efficiency ; plant nutrition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To study the titanium effect on P nutrition, a greenhouse experiment withCapsicum annuum L., cv. Bunejo plants growing under differential P fertilization was conducted. All the plants were grown under identical conditions and they only differred in the P fertilization and in Ti supply. Plant biomass production of the Ti-untreated plants was affected by the diminution of the P-feed, but the plants growing under the lowest P supply did not showed any deficiency symptom during the crop cycle. All the Ti-treated plots showed a significative increase of the plant biomass against their corresponding untreated references. The biomass enhancement was mainly caused by the increase of the fruit yield with an absolute enhancement of 62% in the plants growing under the lowest P feed, and of 45% in the plants with a complete P support.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 43 (1995), S. 209-215 
    ISSN: 1573-0867
    Keywords: phosphorus ; saturation ; inventory ; leaching ; eutrophication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The last three decades, pig breeding has evolved towards a specialised, large scaled, land independent bio-industry in the province of West-Flanders. Subsequently, in certain regions, very high amounts of liquid pig manure are produced each year. This pig slurry is used as a fertilizer at a rate which very often exceeds normal agricultural practices. Because of the nonequilibrium between the phosphorus crop requirements and the P-inputs, phosphates accumulate in the soil. However, the phosphate sorption capacity of a soil is limited. Once the sorption capacity is exceeded, phosphates will start leaching through the soil profile. Since, during winter, in these areas, the groundwater table is situated at a depth of less than 1.0 m, phosphate breakthrough might take place. In the sandy loam soil region (± 1000 km2) of the province, an inventory of the P status of the soil was made. The region was sampled according to a regular grid with 2 km intervals. At random, some sample points were only 500 m apart. This resulted in a total of 296 samplings. In view of fertilizer recommendations, lactate extractable P of the plough layer (0-30 cm) was determined. A maximum value of 101 mg P 100 g−1 of air dry soil, a minimum value of 6 mg P 100 g−1 and a median value of 31 mg P 100 g−1 were found, indicating that for half of the spots monitored, the P status of the soil is high to very high. An oxalate extraction was done to investigate the phosphate saturation of the soil profile (0-90 cm). Based on a critical phosphate saturation degree of 30%, more than half of the soil profiles are phosphate saturated. Phosphate leaching at a rate higher than 0.1 mg ortho-P 1−1 at a depth of 90 cm can be expected. Therefore, a restriction of the P fertilization should be highly recommended. The geostatistical processing of the data using block kriging resulted in a spatial continuous estimate of the phosphate saturation degree. A good agreement was found between the pig density and the phosphate saturation degree of the soil profile.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 37 (1994), S. 107-113 
    ISSN: 1573-0867
    Keywords: Ensete ventricosum ; fertilizer response ; nitrogen ; phosphorus ; potassium ; sulphur ; starch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ensete (Ensete ventricosum W. Cheesm.) is a root crop which stores starch in the root and in the lower part of the stem. It is grown in the southwest of Ethiopia and due to its drought resistance, it is of outstanding importance for the supply of food to the local population. Until now virtually nothing is known about the response of Ensete to fertilizer application. Field trials carried out on three representative soils in Ethiopia showed that Ensete biomass yields were increased significantly on all three soils by nitrogen and phosphorus application. Potassium had only marginal effect on biomass growth but favourably influenced starch production. Sulfate application had no major impact on growth and starch yield. The yield response was well related to the level of available nutrients in the soil, as determined by electroultrafiltration (EUF). Leaf analysis provided preliminary evidence that optimum levels of N, P, and K may be 3.8%, 0.3%, and 4.8%, respectively.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 45 (1995), S. 221-233 
    ISSN: 1573-0867
    Keywords: fertilizer recovery ; modelling ; nitrogen ; nutrient efficiency ; nutrient surplus ; phosphorus ; Poland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Research on nutrient losses from agricultural systems should try to relate these losses to farm characteristics. This was done for private farms in two districts in Poland. Using data from a farm survey, nutrient surpluses and Nutrient Use Efficiency (NUE, defined as the ratio of outgoing and incoming nutrients) were calculated for nitrogen and phosphorus. Both nutrient surplus and NUE are relatively high. A model was developed to estimate surpluses and NUE from farm characteristics like location, farm size, fertilizer application level, animal density, grass production and sugar beet or potato area. The results of the model are satisfying for nutrient surplus (R2=0.9) and nitrogen NUE (R2=0.4). Estimation of phosphorus NUE was not satisfactory. High surpluses are associated with high fertilizer applications, high animal density and high grass production while an increasing share of sugar beets leads to lower surpluses. A high nitrogen NUE is associated with low fertilizer applications, low animal density and little grass production, and with a high sugar beet area share. Results suggest that, with exception of sugar beet, fertilizer recovery in Poland is very low. Sugar beet, however, combines high fertilizer applications with low surpluses and high NUE. The outcome of the model can be used in the design of environmental policies. The paper ends with some remarks on the type of measures that can be taken, and the effects these will have on private farms in Poland.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 46 (1996), S. 81-90 
    ISSN: 1573-0867
    Keywords: elemental sulfur ; granule size ; nitrogen ; phosphorus ; potassium ; S oxidation ; sulfur fertilizers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experiments were undertaken to determine the effect of granule size and nutrients in granulated compound fertilizers fortified with finely divided elemental sulfur (So) on the rate of So oxidation. In one experiment, So was banded together with or apart from triple superphosphate (TSP) while in two others, So was granulated with nutrient and inert carriers. A fourth experiment examined response to S in an So-fortified TSP from a range of granule sizes. Response and, in some cases, So recovery (using 35S labels) by test crops (maize, wheat, upland rice) was measured. In all experiments, P mixed with So increased plant growth and S recovery above treatments in which P and So were physically separated. There was however, no effect of distance of separation on S recovery. In one experiment, N as urea and N and P as diammonium phosphate (DAP) were also found to enhance response to So although to a lesser degree than P alone. These observations were attributed to a nutritional requirement of So-oxidizing microorganisms for P and N. Granulation of So with carriers also influenced oxidation rate, as inferred from the fertilizer S recovery. For a given So concentration, the effect was inversely proportional to the mean diameter of granules. It is shown that this relationship can be explained if one assumes that So particles in granules collapse into a fixed number of aggregates per granule irrespective of granule size when the soluble nutrient carrier dissolves and diffuses away from the point of application.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    ISSN: 1573-0867
    Keywords: long-term experiments ; phosphorus ; rice ; nutrient balance ; phosphorus uptake ; fertilizer P response ; soil testing ; ion-exchange resin ; phosphorus supplying capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Data from long-term experiments at 11 sites in Asia with a wide range of nutrient input treatments and yield levels were used to quantify crop P requirements of rice (Oryza sativa L.) and the P balance in intensive, irrigated rice systems. Uptake of 1.8–4.2 kg P was required to produce one ton of grain yield. Physiological P use efficiency varied between 220 to 900 kg grain kg P-1. Without added P, there was a net loss of 7 to 8 kg P ha-1 per crop; with added P there was a net gain of 4 to 5 kg P ha-1 per crop. Phosphorus adsorption kinetics on mixed-bed ion-exchange resin capsules provided an integrative measure of soil P status, P diffusion, and acid-induced P solubilization. The resin capsule was a sensitive tool to characterize buildup or depletion of soil P as a result of different P balances. Both Olsen-P and the resin capsule were suitable methods to predict P uptake of tropical lowland rice. It is hypothesized that both methods measure a similar soil P pool which is soluble under alkaline, aerobic conditions but transformed into acid-soluble P froms as a result of submergence and reduction. Present recommendations for P fertilizer use on rice of 20–25 kg P ha-1 are adequate to maintain yields of 5–6 t ha-1, but sustaining higher yields of 7–8 t ha-1 will require farm-specific management strategies based on knowledge of the long-term P balance and soil P-supplying capacity.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 46 (1996), S. 71-79 
    ISSN: 1573-0867
    Keywords: ammonium poly-phosphate ; diammonium orthophosphate ; fertilizer reaction ; gram ; Indian soils ; phosphorus ; P uptake ; single superphosphate ; triple superphosphate ; yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Laboratory studies on the characterization of soil-fertilizer P reaction products were carried out by reacting three-soils occurring in a toposequence in the plateau region of Bihar (India) with saturated solutions of diammonium orthophosphate (DAP), triple superphosphate (TSP) and ammonium polyphosphate (APP) for 1 hour and 24 hours. The reaction products (precipitates) formed in the solutions after 120 days of incubation were isolated and identified through X-ray diffraction technique. Results indicate the formation of Brushite [CaHPO4 · 2H2O, Strengite (FePO4 · 2H2O), Variscite (AIPO4 · 2H2O) and Fe4(P2O7)3 as major soil-fertilizer P reaction products in these soils with ortho-and polyphosphates as source of phosphorus. Pot cultures were used to evaluate the relative efficiency of reaction products (Struvite, Brushite, Variscite and Strengite), orthophosphates (DAP and SSP) and polyphosphate (APP) as sources of P for gram (Cicer arietinum L.) in a typical acid soil. Results indicate significant response of gram to different sources and level of added P. The dry weight and P uptake at 0, 6 and 12 mg P kg-1 soil were 0.406, 0.519 and 0.609 (g pot-1); and 0.289, 0.428 and 0.575 (mg P pot-1), respectively. Among the sources , struvite proved to be superior or equally effective as APP, DAP or SSP as sources of P for gram. Uptake of P also varied significantly with different P sources and levels of P application. Strengite was least effective in enhancing yield and P uptake by the crop.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 44 (1995), S. 1-8 
    ISSN: 1573-0867
    Keywords: aerobic incubation ; cation-anion-exchange resin ; phosphorus ; resin beads ; resin membranes ; suspension incubation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Six Portuguese soils of varying P sorption capacity were incubated aerobically at 30° C without and with added P in order to give 0.1.mg P L−1 in the soil solution. Two methods of measuring extractable P were compared: (i) mixed-bed cation-anion-resin beads in bags and (ii) a simpler method with anion-resin membrane only. The bag method extracted about twice and 1.5 times as much as the strip method, respectively, without and with added P. The relationships were much closer after one extraction for 2 hours (r = 0.982, p 〈 0.01) instead of the cumulative extraction of 24 hours (r = 0.635,p 〉 0.05.). P recovery after incubation was inversely related to some soil properties as organic matter, buffer capacity, selective dissolution Al forms (Alox and Ald) and P sorption. It is suggested that the simpler resin membrane method is more adequate to assess P for many studies of P reaction with soil. A simpler incubation method was tried, consisting of incubation as a soil suspension in water at a high temperature (50° C). The results suggested that this method gave similar results to aerobic incubation, with the advantage that there was no need to measure the required and final water contents of incubated soil.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 46 (1996), S. 179-187 
    ISSN: 1573-0867
    Keywords: electrical conductivity ; leaching ; nitrogen ; pH ; phosphorus ; potassium ; release pattern ; slow-release fertilizers ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We studied the effect of temperature on the release of N, P, and K from slow-release fertilizers (SRF). The study was conducted in micro-lysimeters filled with moist peat medium. Increasing the temperature from 4 to 12°C slightly increased N release from three different slow-release N (SRN) carriers with different particle sizes and coating thicknesses. At 21°C the rate of release was significantly different than the other two temperatures. Urea formaldehyde (UF), sulphur coated urea (SCU) and coated calcium nitrate (CCN), incubated in sphagnum moss peat, released between 3 and 20% of the applied N in six weeks. For eight synthetic and organic NPK carriers, the release pattern was similar to UF and SCU. However, the leaching losses of N from the NPK fertilizers were up to twenty times more than for the SRN products. Except for Osmocote® and Duna, which released 30–40% of the applied N as mineral-N within six weeks, all other slow-release and slowly mineralized NPK carriers acted like readily water-soluble compound NPK. Temperature did not affect the nutrient release from NPK fertilizers.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 50 (1998), S. 321-324 
    ISSN: 1573-0867
    Keywords: nutrient modelling ; leaching ; nitrogen ; phosphorus ; schematization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In context of preparing the Fourth National Policy Document on Water Management in the Netherlands effects of different scenarios of fertilizer management on nitrogen (N) and phosphorus (P) leaching from rural areas into Dutch surface waters were analyzed. The manuscript offers insight into the model instrument that is used to simulate the different scenarios. Main parts of the modelinstrument are: a procedure to schematize the Netherlands in horizontal areal units, field scale mechanistic models for water and nutrient behaviour in the soil and an empirical model for fertilizer additions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    ISSN: 1573-0867
    Keywords: agriculture ; catchment ; fertilizer ; historical ; manure ; nitrate ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A suggested increase in the growth of macrophytic algae within the Ythan estuary (N.E. Scotland) over recent years has been linked to the increased amounts of nitrogen in the form of NO3–N entering the estuary from the river. The increased NO3 concentration in the river has been associated with recent changes in farming practices in this predominantly agricultural catchment. Terrestrially derived phosphorus is also considered to contribute increasingly to eutrophication of fresh waters. Historical agricultural census data together with appropriate surveys of fertilizer practice were used to calculate the total quantities of fertilizer and manure derived N and P applied annually over the wholeYthan catchment during the period 1960 – 1990. While the total agricultural land area has remained similar, significant changes in cropping practice have occurred. In particular, a greater proportion of land is given to autumn sown crops while the area of grassland has declined. These changes in farming practice are associated with differences in both the total amounts and timing of fertilizer applied. The use of inorganic N in the catchment has trebled since 1960 and is currently approximately 6400 tonnes (104 kg N/ha). The use of P has decreased by more than a quarter to 1274 tonnes (21 kg P/ha) over a similar time period. There has been no obvious change in total quantity of N and P derived from animal manures, estimated to be 44 and 11 kg per ha, respectively, when averaged over the area of agricultural land. Cattle and sheep numbers have remained relatively constant and together account for approximately 80% of the manure N and 70% of the manure P produced annually. However, poultry have declined by 70% since 1960 while pig numbers have increased six-fold. The average annual application rate of manure derived N over the whole catchment (44 kg/ha) is considerably below that proposed at the farm scale in the EC Nitrate Directive (210–170 kg/ha). However, on a local scale difficulties may arise for large manure producing concerns such as dairy or pig units.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 46
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 55 (1999), S. 7-14 
    ISSN: 1573-0867
    Keywords: fertiliser formulation ; nutrients ; phosphorus ; relative humidity ; soil moisture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphorus lost in runoff from agricultural land leads to the enrichment of surface waters and contributes to algal blooms. Fertilisers are one source of this P. To compare the water available P of different fertiliser formulations in the laboratory it is necessary to control environmental conditions, temperature, relative humidity and soil water content, prior to simulating rainfall. Two chambers were designed in which relative humidity and soil water content were controlled using salt solutions. An initial design comprising a sealed chamber with three layers of soil samples over a salt bath was found to be inferior to a single layer design. The changes in water content of soil samples were used to test the single layer chamber in a constant temperature environment (15 °C) using a saturated KCl solution (90% relative humidity). Based on the final soil water content of the samples, the spatial variation within the chamber was within tolerable limits. The single layer chamber was used for a simulation experiment comparing the water available P of two commercial fertilisers. Using a saturated resorcinol solution (95% relative humidity) soil samples were equilibrated at 15 °C for 21 days, fertiliser added, and the water available P measured up to 600 h after fertiliser application. The results indicate that the amount of water available P was related to the fertiliser compound and exponentially related to the time since fertiliser application. It was concluded that the single layer chamber is suitable for controlling relative humidity and soil water content in trials such as these where the water available P of fertilisers are being compared.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 47
    ISSN: 1573-0867
    Keywords: dairy systems ; feeds ; fertilizers ; phosphorus ; P surplus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Inputs of phosphorus (P) above requirements for production on dairy farms lead to surplus P with increased risk of P transfer in land run-off to surface waters causing eutrophication. The impact of reducing surplus P inputs in purchased feeds and fertilizers on milk and forage production was investigated in a comparison of three dairy farm systems on chalkland soils in southern England over a 3-year period. In accordance with current commercial practice, no attempt was made to regulate P inputs in system 1, which accumulated an average annual surplus of 23 kg P ha-1. Progressive reductions in purchased feed and/or fertilizer inputs into systems 2 and 3 decreased surplus P to 17 and 3 kg ha-1, respectively, without apparently limiting either milk or herbage dry matter production. The estimated reduction in faecal P output from system 3 cows fed a low P diet compared to system 1 cows fed a high P diet was 26%. Milk P concentrations significantly (P 〈0.001) increased in systems 2 and 3 which included maize in the diet. Output of P in milk and meat products, as a proportion of the total dietary P inputs, increased from 28% in system 1 to 36% in system 3. Surplus P was greatest in continuous maize fields receiving both dairy manure and starter P fertilizer. Withholding P fertilizer in system 3 did not reduce P offtake in cut herbage on soils of moderate P fertility. Total annual losses of P in storm run-off and leaching were no greater than annual inputs of P from the atmosphere (0.5 kg ha-1). The results indicate there is scope to reduce surplus P on commercial dairy farms without sacrificing production targets at least in the short term. Purchased feeds are the largest of the P inputs on intensive dairy farms, yet these are rarely quantified on commercial holdings.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 48
    ISSN: 1573-0867
    Keywords: leaching ; phosphorus ; poultry litter ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To determine P loadings, added through poultry litter, sufficient to cause downward movement of P from the cultivated layer of a sandy soil, six rates of poultry litter were applied annually for four years to a site in central England. (total loading 0 – 1119 kg P ha-1). A single extra plot also received an extra 1000 kg ha-1 as triple superphosphate (TSP; total loading 2119 kg P ha-1) and three other treatments received 200 – 800 kg ha-1 P as TSP only. Annual soil sampling in 30-cm increments to 1.5-m depth provided information on P build-up in the topsoil and P movement to depth. There were strong linear trends between P balance (P applied – P removed in crops) and total P, Olsen bicarbonate extractable P and water-soluble P in the topsoil. Phosphorus from TSP and poultry litter fell on the same regression lines, suggesting that both would be equally effective as fertilizer sources. We calculated that 100 kg ha-1 surplus total P would increase the Olsen extractable P content by c. 6 mg kg-1 and the water-soluble P by c. 5 mg kg-1. Thus, relatively large amounts of P would need to be applied to raise soil P status. We found some evidence of P movement into the soil layers immediately below cultivation depth. However, neither soil sampling nor soil solution extracted through Teflon water samplers showed evidence of movement into the deep subsoil (1 m) despite large P loadings.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 49
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 54 (1999), S. 259-266 
    ISSN: 1573-0867
    Keywords: bahiagrass ; manure ; pasture fertilization ; phosphorus ; phosphorus cycling ; Spodosol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Bahiagrass (Paspalum notatum Flugge) pasture fertilization recommendations have traditionally been based upon clipping studies. Inclusion of P from manure, not originally considered when P recommendations were developed for pastures, may minimize the need for P fertilization without reducing bahiagrass production or P uptake. The objective of this research was to determine if manure contributes greatly to the P crop nutrient requirement. A 2-year field study utilized a factorial arrangement of 0 and 6.9 Mg air-dried manure ha-1 with 0, 17, 34, 51, and 68 kg inorganic P ha-1 from triple superphosphate to evaluate bahiagrass yield, root distribution, and P uptake response on a Myakka fine sand (sandy, siliceous, hyperthermic Aeric Alaquod). Because air-dried manure was used in the field study, a greenhouse study was employed to confirm that there were no differences in bahiagrass yield or P uptake from either air-dried or fresh cattle (Bos spp.) manure sources. There were no manure or manure by P interaction effects on yield or P uptake of bahiagrass indicating that manure source did not effect grass production in the greenhouse. In the field study, bahiagrass roots were distributed into the Bh horizon, and the Bh horizon had at least four times more Mehlich-1 extractable P than that of the Ap horizon. This horizon was most likely acting as a main source for P-uptake by the grass. This observation was further confirmed by no yield response to levels of inorganic P application in 1989. A linear-response-and-plateau (R2=0.196) relationship with a critical point of 15.4 kg P ha-1 was found in 1990. Bahiagrass yield and P uptake were not dependent on P fertilization, either from manure or inorganic P, due to the availability of P from the Bh horizon.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 50
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 35 (1993), S. 217-226 
    ISSN: 1573-0867
    Keywords: calcium ; dry matter distribution ; fertilizer ; harvest index ; magnesium ; manure ; millet ; nitrogen ; nutrient uptake ; phosphorus ; potassium ; Senegal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a fertilizer and manure experiment, millet was grown under four treatments (no fertilizer or manure, farmyard manure, chemical fertilizer, and both). Grain yield and total aboveground biomass production of the unfertilized plot were relatively high. The observed differences in total dry matter production must be attributed to differences in nutrient availability, as amount of rainfall and its distribution were favourable. Results show only small differences in distribution of dry matter among the various plant organs between the best and the non-fertilized treatments. Nutrient supply from natural sources, defined as crop content of N, P, and K at maturity without fertilizer application, amounted to 104, 16 and 103 kg ha−1, respectively, which are very high values. Total uptake of calcium and magnesium is related to that of potassium, as the combined content of these three elements is linearly related to total aboveground biomass production. Minimum removal of nitrogen and phosphorus per ton grain dry matter amounts to 29 and 4kg, respectively, and 9 kg potassium per ton total aboveground dry matter. A possible double function of phosphorus as element of structural biomass and for maintenance of electro-neutrality is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 51
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 36 (1993), S. 95-103 
    ISSN: 1573-0867
    Keywords: eutrophication ; phosphorus ; fertilizer ; Peel-Harvey estuary ; algal blooms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An excess of plant nutrients has caused serious eutrophication in aquatic ecosystems of southwestern Australia manifested by excessive growth and accumulation of green and bluegreen algae. Phosphorus is generally the limiting nutrient for algal growth and phosphatic fertilizers applied to nutrient-deficient, leaching, sandy soils are the main source of P, supplemented by rural industry point sources. Nitrogen is the limiting nutrient in marine embayments with little drainage from the land. Measures to reduce the load of P delivered to drainage include basing fertilizer application rates on soil testing for P and the use of less soluble P fertilizers. Catchment management plans are being implemented with community involvement to reduce P loads and maintain agricultural production. This introductory paper reviews the history of eutrophication in southwestern Australia and of studies into its causes, principally in the large Peel-Harvey estuary. It briefly summarises other papers in this special issue concerned with different aspects of the problem: how to fertilize the land without causing eutrophication.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 52
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 36 (1993), S. 115-122 
    ISSN: 1573-0867
    Keywords: phosphorus ; retention ; release ; sandy soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to manage phosphorus (P) losses from soils to waterbodies, knowledge of the mechanisms through which P is retained or released from the soil is essential. Sandy soils of the Peel-Harvey catchment (Western Australia) were subjected to a range of environmental and management factors in the laboratory and field in order to gain an understanding of the mechanisms that affect the magnitude of P losses. Sandy soils accumulated P, despite having little sorption capacity, and this accumulation could be monitored by measuring an acid-extractable fraction. The potential, short-term P loss could be estimated by determination of water-soluble soil solution P prior to winter rains. An annual cycle of the change in arbitrarily defined soil-P pools is discussed in relation to environmental and management factors. Laboratory experiments indicated that P rundown and potential annual P loss in the absence of P fertilizers could be estimated using bicarbonate extractable P. Phosphorus losses were decreased by the application of fertilizers with a low content of water-soluble P. The low ability of sandy soils of the Peel-Harvey coastal catchment to retain P, when compared to other Western Australian soils, is because of low contents of clay minerals and iron and aluminium hydrous oxides.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 53
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 26 (1990), S. 229-235 
    ISSN: 1573-0867
    Keywords: Grass ; wheat ; nitrogen nutrition ; dilution curve ; mineral content ; mineral removal ; phosphorus ; potassium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The important effect of nitrogen in changing the patterns of mineral content and mineral removal is analysed for grass swards and wheat. Different models are proposed; accumulated dry matter developed throughout a growing period is shown to be an excellent reference for assessing the evolution of the plant mineral content and the mineral removal the growing crop. Applications in diagnosing mineral nutrition status and optimising fertilizer use are proposed and discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 54
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 3 (1982), S. 13-16 
    ISSN: 1573-0867
    Keywords: cocoa ; nitrogen ; phosphorus ; soil analysis ; Nigeria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract No extensive investigation on the effect of fertilizers on Amazon cocoa variety (Theobroma cacao L.) has been performed in Nigeria. Therefore eight fertilizer treatments involving nitrogen and phosphorus, replicated six times at four locations across southern Nigeria, were established in 1973. The four N levels (N0, N1, N2, N3) involved were 0, 80, 160 and 240 kg ha−1 y−1, and the two P levels (P0, P1) were 0 and 67 kg ha−1 y−1. Results of the first 5 years of fertilizer application are reported. Response to P was observed at all locations, and the response was statistically significant at 2 of the locations. There was no response to the application of nitrogen. The data suggest, however, that there is only a response to phosphorus when nitrogen is applied.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 55
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 32 (1992), S. 223-227 
    ISSN: 1573-0867
    Keywords: Soil testing ; phosphorus ; relative yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A greenhouse experiment, with Okra (Abelmoschus esculentus L.) as the test crop, was conducted on twenty-one soils ranging in Olsen's extractable phosphorus from 1.8 to 15.5µg Pg−1 soil. The experiment was conducted at Punjab Agricultural University, Ludhiana, India. The soils were nonsaline with pH ranging from 7.7 to 8.6. A critical level of 2.55µg Pg−1 soil was predicted by Cate and Nelson's (1971) statistical procedure. Because of a wide range in relative yields, this value did not accurately predict response to applied P. An approach to compute minimum response to applied fertilizer, which is likely to be obtained at a particular Olsen P level, has been presented. It involves calculation of lower 60 percent confidence limits for relative yield and fitting loge-linear regression to the transformed data. The regression was tested on a published data set and was found to hold well.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 56
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 32 (1992), S. 259-267 
    ISSN: 1573-0867
    Keywords: Nitrogen ; phosphorus ; timber increment ; fertilization ; Pinus radiata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two trials inPinus radiata growing on different sites in N.S.W. allowed consideration of fertilizer applications after 2nd or 3rd thinning. The trials included factorial applications of N and P at a single thinning intensity plus a further treatment which allowed assessment of different thinning intensities. The most significant growth responses were obtained by application of N and P in combination. The largest response (additional productivity compared with the unfertilized control) occurred 4 years after application and after 7 years there was no additional absolute response for either of the two sites. The largest fertilizer response was 70 m3 ha−1 over 7 years on one site and 36 m3 ha−1 on the other, indicating differences in absolute responses between sites. It was concluded that in planning treatments the most responsive sites near the end of the rotation should be selected to maximise economic returns. Foliage analyses indicated differences between sites at the commencement of the study. It was concluded that either a single year of foliage analyses at study commencement is of value, or sampling every year of the study should be used to analyse responses, but a single year of analysis during or at the end of the study would not be of value.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 57
    ISSN: 1573-0867
    Keywords: interaction ; isotopic exchange ; phosphorus ; plant-availability ; selenium ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphate, applied at 5µg P cm−3, decreased selenite sorption by from 30–70% in three soils studied. Both maximum sorption (Xm) and the binding-energy of sorption as indicated by the binding-energy related constant (k) or the molar free energy (ΔG) of the sorption reaction derived from the Langmuir equation were considerably decreased. On the other hand, phosphate sorption was decreased by increasing concentration of selenite from 0.2µg Se cm−3 to 1.0µg Se cm−3 in the initial solution. The competitive sorption of phosphate with selenite was likely the main mechanism involved in the P-Se interactions. The competitively sorbed selenite exhibited much larger desorption in 0.01M CaCl2 solution, more readily extractable to 0.5M NaHCO3 and significantly higher isotopic exchangeability compared to that sorbed without the competing anion. Results from pot trial using ryegrass indicated that phosphate application increased more efficiently the plant-availability of applied fertilizer Se than that of indegeneous Se in soil.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 58
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 47 (1996), S. 243-250 
    ISSN: 1573-0867
    Keywords: fertilizer value ; nitrogen ; phosphorus ; poultry manure ; urea ; wetland rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Poultry manure applied alone or in combination with urea at different N levels was evaluated as a N source for wetland rice grown in a Fatehpur loamy sand soil. Residual effects were studied on wheat which followed rice every year during the three cropping cycles. In the first year, poultry manure did not perform better than urea but by the third year, when applied in quantities sufficient to supply 120 and 180 kg N ha−1, it produced significantly more rice grain yield than the same rates of N as urea. Poultry manure sustained the grain yield of rice during the three years while the yield decreased with urea. Apparent N recovery by rice decreased from 45 to 28% during 1987 to 1989 in the case of urea, but it remained almost the same (35, 33 and 37%) for poultry manure. Thus, urea N values of poultry manure calculated from yield or N uptake data following two different approaches averaged 80, 112 and 127% in 1987, 1988 and 1989, respectively. Poultry manure and urea applied in 1:1 ratio on N basis produced yields in between the yields from the two sources applied alone. After three cycles of rice-wheat rotation, the organic matter in the soil increased with the amount of manure applied to a plot. Olsen available P increased in soils amended with poultry manure. A residual effect of poultry manure applied to rice to supply 120 or 180 kg N ha−1 was observed in the wheat which followed rice and it was equivalent to 40 kg N ha−1 plus some P applied directly to wheat.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 59
    ISSN: 1573-0867
    Keywords: pasture fertilization ; phosphorus ; potassium ; nutrient budget ; nutrient efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Dairy farming is the main agricultural activity of the Basque Country. A dairy farm is characterized as a system with soils and crops, forage, cattle and manure as main components, and in such a system, nutrient cycling is very important to maintain soil fertility and optimize forage production. To quantify nutrient transfers in the cycle, a simple system was developed and has been applied to seventeen farms to examine its ability to achieve a balanced P and K fertilization. These farms have provided data on inputs (fertilizer, feeds, concentrates), pasture and manure management, and outputs (milk production), and soil samples have been taken from farm pastures. Phosphorus and K in excreta and uneaten pasture is used with a relatively high efficiency as suggested by the relatively high efficiency of P and K utilization by the pasture that usually ranges from 70 to 90%. Concentrate feeding (3000 kg cow−1 yr−1) represents one of the main P and K inputs in Basque Country dairy farms, averaging 26 and 66 kg ha−1, respectively. Besides, release of K in the soil through slow liberation from non-exchangeable sites was estimated as 30 kg ha−1. Thus, a high efficiency in excreta recycling would diminish substantially P and K mineral fertilizer needs. Farm nutrient budgets appear to be a convenient tool for determining nutrient shortages and surpluses at farm level, and thus they are considered as a first step to support a better management of maintenance fertilization of permanent pastures.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 60
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 5 (1984), S. 371-382 
    ISSN: 1573-0867
    Keywords: nitrogen ; phosphorus ; dry areas ; apparent recovery fraction ; fertilizer management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Agronomic efficiency (AE) is defined as the increase in economic yield of a crop per unit fertilizer applied. Components of AE are physiological efficiency and apparent recovery fraction. The latter can be further separated into uptake efficiency and availability index. Ways to increase the nitrogen fertilizer use efficiency in rainfed agriculture through fertilizer management are discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 61
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 45 (1995), S. 193-197 
    ISSN: 1573-0867
    Keywords: cation activity ; phosphorus ; potassium chloride ; soil solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The electrolyte concentration of the soil solution affects the availability of some nutrients in the soil, especially of P, but it is not know at what salt concentration the reactions start to be significantly affected and their magnitude. This study was carried out to evaluate the effect of rates of potassium chloride (KCl) on some soil parameters that determine supplying of P, K, Ca, Mg, and Al in an unlimed acid soil. Increasing rates of KCl (from zero up to 2000 mg K kg−1) were applied to soil samples fertilized with 360 mg P kg−1. Solution (Cli) and exchangeable (Csi) forms of P, Ca, Mg, K, and Al were determined in the treated soil samples after 30-days of incubation; cation activity in solution and their selectivity coefficients were then calculated. Addition of KCl at rates equal to or above 500 mg K kg−1 caused a large relative increase on P in the soil solution (Pli) but a small and insignificant increase on the absolute value of Pli. All forms of soil K increased with increases on K applied, and buffer power for K varied according to the range of soil K. At all KCl rates, K displaced Ca, Mg, and Al from the solid phase to the soil solution, but had no effect on the extractable values. The relative preference of cations for the adsorption sites increased with increase on cation valency, and only those selectivity coefficients involving K were affected by K applied.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 62
    Electronic Resource
    Electronic Resource
    Springer
    Space science reviews 83 (1998), S. 75-86 
    ISSN: 1572-9672
    Keywords: Solar wind ; Heliosphere ; Ulysses ; SOHO ; MHD waves ; Turbulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The solar wind in the inner heliosphere, inside ~ 5 AU, has been almost fully characterized by the addition of the high heliographic latitude Ulysses mission to the many low latitude inner heliosphere missions that preceded it. The two major omissions are the high latitude solar wind at solar maximum, which will be measured during the second Ulysses polar passages, and the solar wind near the Sun, which could be analyzed by a Solar Probe mission. Here, existing knowledge of the global solar wind in the inner heliosphere is summarized in the context of the new results from Ulysses.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 63
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 63 (1991), S. 305-313 
    ISSN: 1572-9613
    Keywords: Turbulence ; diffusion ; helicity ; convection ; incompressible fluids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Through the use of the Novikov-Furutsu formula for Gaussian processes an equation is obtained for the diffusion of the ensemble average of a passive scalar in an incompressible turbulent velocity field in terms of the two-point, two-time correlator of this field. The equation is valid for turbulence which is not necessarily homogeneous or stationary and thus generalizes previous work.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 64
    Electronic Resource
    Electronic Resource
    Springer
    Mangroves and salt marshes 2 (1998), S. 37-42 
    ISSN: 1572-977X
    Keywords: mangrove ; phosphorus ; distribution ; dynamics ; exportation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The distribution and dynamics of phosphorus have been studied in the mangroves of Sepetiba Bay, Brazil. Leaf fall contributes 3.0 kg P ha=1yr=1to the sediment. The total above ground biomass of the R. mangle stand was about 65.3 t ha=1, the P accumulation was 3.9 kg P ha=1where 63% of the total P-biomass was accumulated in the leaves. The biomass of below ground roots was about 8.2 tha=1 and accumulated 16% of total P-biomass. Sediment contained 452 kg P ha=1 where P combined with calcium (P-Ca) was the main fraction (260 kg ha=1). The annual flux of P as litter fall was small (〈 1%) compared to total P in the sediment reservoir. The annual export of P by macrodetritus corresponds to 0.05% of the total sediment reservoir.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 65
    Electronic Resource
    Electronic Resource
    Springer
    Biodegradation 14 (1991), S. 167-191 
    ISSN: 1572-9729
    Keywords: leaf longevity ; nitrogen ; nutrient use efficiency ; phosphorus ; requirement ; retranslocation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Aboveground nitrogen (N) and phosphorus (P) requirement, retranslocation and use efficiency were determined for 28-year-old red oak (Quercus rubra L.), European larch (Larix decidua Miller), white pine (Pinus strobes L.), red pine (Pinus resinosa Ait.) and Norway spruce (Picea abies (L) Karst.) plantations on a similar soil in southwestern Wisconsin. Annual aboveground N and P requirements (kg/ha/yr) totaled 126 and 13 for red oak, 86 and 9 for European larch, 80 and 9 for white pine, 38 and 6 for red pine, and 81 and 13 for Norway spruce, respectively. Nitrogen and P retranslocation from current foliage ranged from 81 and 72%, respectively, for European larch, whereas red pine retranslocated the smallest amount of N (13%) and Norway spruce retranslocated the smallest amount of P (18%). In three evergreen species, uptake accounted for 72 to 74% of annual N requirement whereas for two deciduous species retranslocation accounted for 76 to 77% of the annual N requirement. Nitrogen and P use (ANPP/uptake) was more efficient in deciduous species than evergreen species. The results from this common garden experiment demonstrate that differences in N and P cycling among species may result from intrinsic characteristics (e.g. leaf longevity) rather than environmental conditions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 66
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 118 (1980), S. 494-527 
    ISSN: 1420-9136
    Keywords: MST radar ; Gravity waves ; Turbulence ; Stratospheric structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Powerful VHF radars are capable of almost continuously monitoring the threedimensional velocity vector and the distribution of turbulence in the middle atmosphere, i.e. the stratosphere and mesosphere. Methods of radar investigations of the middle atmosphere are outlined and the basic parameters, mean and fluctuating velocities as well as reflectivity and persistency of atmospheric structures, are defined. Results of radar investigations are described which show that the tropopause level as well as a criterion on the stability of the lower stratosphere can be deduced. Besides mean wind velocities, VHF radars can measure instantaneous velocities due to acoustic gravity waves. The interaction of gravity waves with the background wind is discussed, and it is shown that cumulus convection is an effective source of gravity waves in the lower stratosphere. The vertical microstructure of the stratosphere, manifesting itself in thin stratified sheets in which temperature steps occur, is investigated by applying knowledge from investigations of the oceanic thermocline. Possible origins, like shear generation and lateral convection of the microstructure of the stratosphere, are discussed. Observations of gravity waves in the mesosphere are reviewed and their connection with turbulence structures is pointed out. Finally, some open questions which could be answered by further VHF radar investigations are summarized.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 67
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 120 (1982), S. 95-107 
    ISSN: 1420-9136
    Keywords: Boundary layer ; Spectral density ; Turbulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We have carried out a series of recordings reproducing the small scale structures of temperature and windspeed within the boundary layer. The results obtained have been processed by computer and a direct comparison made between the slope of the spectral density functions and the theoretical slopen=5/3 defining the turbulence in the region of the inertial subrange. The measurements made at various altitudes on thin atmospheric samples demonstrate the variability of the spectral density slope with altitude. The hypotheses put forward by A. M. Obukhov, R. Bolgiano, G. H. Shur, P. Misme, A. Monin or S. Panchev, for example, enable the spectral variations and certain discontinuities in the turbulence observed during the experiments, within and beyond the boundary layer, to be explained.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 68
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 120 (1982), S. 648-661 
    ISSN: 1420-9136
    Keywords: Atmospheric turbulence ; Entrainment ; Turbulence ; Karman constant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract This paper extends the theory of the entity and entrainment model of turbulence to obtain a numerical value of von Karman's constant,k=0.37. The formula is, $$k = (2a^3 /A)^{{1 \mathord{\left/ {\vphantom {1 4}} \right. \kern-\nulldelimiterspace} 4}} \ln \beta $$ where,a=1/12 is the entrainment constant,A=1 is the turbulent decay constant, and β is the ratio in height of the successive self-similar layers of the theory, where β is evaluated as β=e 2. These new values fork and β improve the surface roughness length estimates derived from this theory.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 69
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 120 (1982), S. 758-771 
    ISSN: 1420-9136
    Keywords: Diffusion ; Turbulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Dye plumes were generated at three depths in the seasonal thermocline between 7 and 11 m, 22 km south of Key West on 21 August 1980 and photographed at about 10 second intervals with an underwater camera system. Eleven pairs of consecutive pictures are analyzed to determine the mean current vertical shear and the width of the plumes by positioning reference points relative to the rod attached to the camera system. The relative distances of reference points are calibrated with the stereophotogrammetric method for one pair. The eddy diffusivity is calculated by use of a model of turbulent diffusion developed byTaylor (1921). Its values range from 5 to 25 cm2s−1 for the plume widths ranging from 33 to 132 cm. The Richardson number is calculated for each pair of pictures with the vertical density gradient estimated from temperature profiles. Its values are higher than the critical value of 0.25 except for one case. The diffusivity was higher by orders of magnitude than the molecular one and indicates the presence of turbulence together with billow like features of the plumes in spite of high Richardson numbers. This suggests that the billow turbulence might be caused by effects of surface gravity waves and not by the Kelvin-Helmholtz instability.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 70
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 132 (1990), S. 457-479 
    ISSN: 1420-9136
    Keywords: Turbulence ; mesures aéroportées ; fluctuation de pression ; presso-corrélations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Résumé Nous avons décrit dansBardeau et al. (1987), la réalisation, le fonctionnement et les tests d'un microdébitmètre basé sur l'anémométrie à fil chaud. Il a été particulièrement montré que cet appareil était bien adapté aux mesures de pression et pression différentielle avec une grande sensibilité et une très faible constante de temps. Nous présentons ici les applications qui ont été faites de ce capteur aux mesures à haute résolution à bord d'avions instrumentés pour la recherche atmosphérique. L'avion utilisé était spécialement équipé pour les mesures de turbulence et permettait donc l'acquisition d'un grand nombre de paramètres indispensables à l'analyse des données de ce capteur. Dans les applications aéronautiques qui ont été faites, le capteur a surtout été utilisé en tant que variomètre. Les comparaisons avec les mesures standards d'altitude par pression et couplages pression-données inertielles montrent que cet instrument pourrait apporter une contribution intéressante dans le domaine de la mesure à haute fréquence des fluctuations de pression.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 71
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic sciences 54 (1992), S. 58-76 
    ISSN: 1420-9055
    Keywords: Eutrophication ; lake management ; phosphorus ; nitrogen ; chlorophyll-a ; slope estimator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We estimate the response of chl-a (mg · m−3) to changes in concentrations of total phosphorus (TP) by calculating the slopeS = Δchl-a/ΔTP in chl-a =f(TP) graphs. Results show that in years where algae are P-limited oligotrophic lakes respond less (median slope 0.21) to changes in nutrient concentrations than eutrophic lakes, (median slope 0.31) and these again less than hypereutrophic lakes, (median slope 1.02). We find no saturation value for the slope within the TP range considered (6–480 mg · m−3). Chl-a in eutrophic lakes responds more frequently to non-nutrient factors than oligotrophic and hypereutrophic lakes. Results obtained by replacing TP with a new nutrient parameter, TP′ = 0.056 · TP · IN0.226, in which inorganic nitrogen, IN, is factored in, suggest that nitrogen has an influence on chl-a in oligotrophic lakes. Blue-green algae respond less to changes in TP than other algal species, e.g., diatoms.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 72
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic sciences 54 (1992), S. 381-390 
    ISSN: 1420-9055
    Keywords: Eutrophication ; phosphorus ; lake restoration ; internal restoration measures for lakes ; Swiss lakes ; Lake Lugano (Lago di Lugano)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In most lakes eutrophication is linked to an excessive input of phosphorus. Lake restoration by reduction of P-input (external measure) has led to a considerable drop of the P-concentration in all major Swiss lakes as well as in many other lakes. Internal restoration measures such as artificial mixing, drainage of hypolimnetic water, flushing, aeration, biomanipulation and others serve to improve and accelerate the response of a lake to external measures. For the case of Lago di Lugano, a simple two-box model is employed to demonstrate that a reduction of the P-input to about 25% of the present values is necessary to reach the “P-criterion” (P-concentration below 30 µg/l). Internal measures could possibly accelerate the extremely slow response of the northern basin.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 73
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic sciences 55 (1993), S. 132-142 
    ISSN: 1420-9055
    Keywords: nitrogen ; phosphorus ; uptake ; regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dissolved inorganic nutrient pools are small relative to particulate pools, and dissolved pools turnover rapidly. It has been observed that pools change little from day to day on the sampling scales usually employed. A simple model is presented where uptake and regeneration rates balance to cause a local steady state concentration for dissolved inorganic nutrients. Enrichment and dilution perturbation experiments with lake water support the idea of steady state nutrient concentrations. Although inorganic nutrient concentrations are often controlled by biota, the absolute concentrations present tell little about the activity of that biota.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 74
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic sciences 56 (1994), S. 16-28 
    ISSN: 1420-9055
    Keywords: Chlorophyll-a ; phosphorus ; nitrogen ; lake ecosystem ; nutrient limitation ; regression analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Regression results based on data from 46 northern temperate lakes show that total phosphorus (TP) is the best predictor for phytoplankton (as chl-a) at lower trophic levels, TP 〈 200 mg · m−3. A regression including both TP and TN as regressors is the best predictor for lakes with TP 〉 200 mg · m−3. However, the good correlation is probably due to a high correlation between lake average chl-a (all years observed) and lake average TP and TN. Within single hypereutrophic lakes, TN alone is the best predictor. It was not possible to identify a medium trophic domain where TN and TP in combination was the best predictor for chl-a. The ratio TN:TP in the water decreases from about 40 to about 5 with increasing trophic level. Optimum TN:TP ratio for algal species with high abundance during late summer and autumn reflects this decreasing ratio, but within a lesser range, i.e., 20 to 5. In contrast, TN:TP ratios for species abundant during the early vernal period showed no, or an inverse, relation to the TN:TP ratio of the water.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 75
    Electronic Resource
    Electronic Resource
    Springer
    Environmental geology 30 (1997), S. 224-230 
    ISSN: 1432-0495
    Keywords: Key words Sediment ; Washington ; DC ; Pollution ; phosphorus ; nutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Sediments in the rivers and basins around Washington, DC, have high concentrations of phosphorus, which, based on geographic distributions, is largely derived from urban runoff and municipal sewage. Dissolved-particulate phosphate exchange reactions and biological uptake of dissolved phosphorus from the water column may be an added source of phosphorus to the sediments. Concentrations of total sedimentary phosphorus ranged from 24 to 56 μm P/g-dw, and were highest in areas near combined sewer outfalls. As a part of this study, sedimentary phosphorus was fractionated into Fe-P, Ca-P, Al-P, and organic phases using a selective-sequential leaching procedure. The distribution of the phases in all sediments analyzed follow the order , Fe-P〉Ca-P〉Al-P. Spatial variations in the amounts of phosphorus in the different phases is related to the sources of phosphorus to the area. The proportions of occluded Al-P and organic P are 10–20% of the total P, respectively. This suggests that phosphorus from natural sources is small compared to anthropogenic inputs in this area. The high leachable Fe-P and Ca-P in these sediments might contribute a substantial amount of P to the water column under conditions of remobilization.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 76
    ISSN: 1432-0495
    Keywords: Nitrogen ; phosphorus ; Precipitation collector ; Nutrients rates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The contribution of nitrogen and phosphorus due to precipitation constitutes the second most important route after superficial runoff. The sampling carried out during a two-year period by means of a precipitation collector allows us to determine the contribution of this route both qualitatively and quantitatively. Nitrogen is mainly supplied in an inorganic form, while phosphorus is principally supplied as orthophosphate. During the period of this study (March 1986–February 1988) it was found that in the Santillana Reservoir Watershed the level of nitrogen supplied by precipitation constitutes an average of 4.87% and the level of phosphorus constitutes 8.01%. The contribution of nitrogen varies in inverse ratio to precipitation and the contribution of phosphorus varies in direct ratio.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 77
    ISSN: 1432-1254
    Keywords: Key words Meteorology ; Turbulence ; Modelling ; Spray drift ; Wind
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract  An insight into the nature of prevailing meteorological conditions and the manner in which they interact with spraying parameters is an important prerequisite in the analysis of the dynamics of agrochemical sprays. Usually, when these sprays are projected from hydraulic nozzles, their initial velocity is greater than that of the ambient wind speed. The flowfield therefore experiences changes in speed and direction which are felt upstream as well as downstream of the spray droplets. The pattern of the droplet flow, i.e. the shape of the streamlines marking typical trajectories, will be determined by a balance of viscous forces related to wind speed, inertial forces resulting from the acceleration of the airstream and pressure forces which can be viewed in terms of the drag forces exerted on the spray droplets themselves. At a certain distance in the ensuing motion, when the initial velocity of the spray droplets has decreased sufficiently for there to be no acceleration, their trajectories will be controlled entirely by the random effects of turbulence. These two transport processes in the atmosphere can be modelled mathematically using computers. This paper presents a model that considers the velocity of spray droplets to consist of a ballistic velocity component superimposed by a random-walk velocity component. The model is used to study the influence of meteorological and spraying parameters on the three-dimensional dynamics of spray droplets projected in specified directions in neutral and unstable weather conditions. The ballistic and random-walk velocity components are scaled by factors of (1–ξ) and ξ respectively, where ξ is the ratio of the sedimentation velocity and the relative velocity between the spray droplets and the surrounding airstream. This ratio increases progressively as the initial velocity of the spray droplet decreases with air resistance and attains a maximum when the sedimentation velocity has been reached. As soon as this occurs, the random-walk process predominates. The computed effects of the release height of spray droplets, atmospheric turbulence intensity, evaporation, drop size spectrum, wind velocity and wind direction on the transport process have been studied and an analysis of spray drift is provided.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 78
    Electronic Resource
    Electronic Resource
    Springer
    Shock waves 4 (1995), S. 237-245 
    ISSN: 1432-2153
    Keywords: Shock ; Turbulence ; Hypersonic inlet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics , Technology
    Notes: Abstract A numerical investigation for an axisymmetric hypersonic turbulent inlet flow field of a perfect gas is presented for a three-shock configuration consisting of a biconic and a cowl. An upwind parabolized Navier-Stokes solver based on Roe's scheme is used to compute an oncoming flow Mach numberM ∞=8, temperatureT ∞=216 K, and pressureP ∞=5.5293×103 N/m2. In order to assess the flow quantities, the interaction between shock and turbulence, and the inlet efficiency, three different flow calculations — laminar, turbulent with incompressible and compressible two-equationk-ɛ turbulence models — have been performed in this work. Computational results show that turbulence is markedly enhanced across an oblique shock with step-like increases in turbulence kinetic energy and dissipation rate. This enhancement is at the expense of the mean kinetic energy of the flow. Therefore, the velocity behind the shock is smaller in turbulent flow and hence the shock becomes stronger. The entropy increase through a shock is caused not only by the amplification of random molecular motion, but also by the enhancement of the chaotic turbulent flow motion. However, only the compressiblek-ɛ turbulence model can properly predict a decrease in turbulence length scale across a shock. Our numerical simulation reveals that the incompressiblek-ɛ turbulence model exaggerates the interaction between shock and turbulence with turbulence kinetic energy and dissipation rate remaining high and almost undissipated far beyond the shock region. It is shown that proper modeling of turbulence is essential for a realistic prediction of hypersonic inlet flowfield. The performed study shows that the viscous effect is not restricted in the boundary layer but extends into the main flow behind a shock wave. The loss of the available energy in the inlet performance therefore needs to be determined from the shock-turbulence interaction. The present study predicts that the inlet efficiency becomes relatively lower when turbulence is taken into account.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 79
    Electronic Resource
    Electronic Resource
    Springer
    Shock waves 5 (1996), S. 275-285 
    ISSN: 1432-2153
    Keywords: Shock reflection ; Diffraction ; Shadowgraph ; Vortex ; Turbulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics , Technology
    Notes: Abstract The accuracy of four industrial shock hydrodynamics codes for blast environments in baffled systems is evaluated based on the shadowgraph data of Reichenbach and Kuhl (1992,3). Both problems involve a planar shock passing through a baffled channel. The numerical methods employed in these codes are representative of two classes, namely, the set of high-resolution schemes advanced in the 1980's, and the classical finite-difference schemes from the late 1960's. The four codes are: (1) the AMR code based on the higher-order Godunov scheme with adaptive grids, (2) the FEM-FCT code based on the flux-corrected transport scheme with unstructured grids, (3) and (4) the finite-difference based HULL and SHARC codes with fixed grids. From the comparisons of these calculations it is concluded that the high-resolution schemes: (1) calculate sharper shocks and sharper density profiles across vortices, (2) predict shear layer rollup forming coherent structures in the spiral vortices immediately down-stream of every baffle, and (3) predict development of inviscid instabilities from these shear layers that, upon interaction with the reverberating shocks in the system, quickly become ‘turbulent’. The finite-difference codes predict essentially laminar behavior for the shear layers. Comparisons with shadowgraph data suggest that both classes of codes are able to predict shock reflections and diffractions in the baffled systems. The high-resolution codes give better agreement in the spiral vortices and the shear layers. As expected, turbulent flow features involving highly dissipative flow fields are not predicted by the high-resolution codes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 80
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 216 (1994), S. 55-65 
    ISSN: 1572-946X
    Keywords: Stars: Hot, Wolf-Rayet ; Turbulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The quantification of stochastic substructures seen propagating away from the centers of emission lines of Wolf-Rayet (WR) stars is extended using the powerful, objective technique of wavelet analysis. Results for the substructures in one WR star so far show that the scaling laws between (a) flux and velocity dispersion and (b) lifetime and flux, combined with (c) their mass spectrum, strongly support the hypothesis that we are seeing the high mass tail-end distribution of full-scale supersonic compressible turbulence in the winds. This turbulence sets in beyond a critical radius from the star and shows remarkable similarity to the hierarchy of cloudlets seen in giant molecular clouds and other components of the ISM. The velocity dispersion is larger on average for substructures (interpreted as density enhanced turbulent eddies) propagating towards or away from the observer, suggesting that the turbulence is anisotropic. This is not surprising, since the most likely force which drives the windand the ensuing turbulence alike, radiation pressure, is directed outwards in all directions from the star. It is likely that a similar kind of turbulence prevails in the winds of all hot stars, of which those of WR stars are the most extreme. The consequences of clumping in winds are numerous. One of the most important is the necessary reduction in the estimate of the mass-loss rates compared to smooth outflow models.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 81
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 221 (1994), S. 371-382 
    ISSN: 1572-946X
    Keywords: Wavelets ; Stars: Hot, Wolf-Rayet ; Turbulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A wavelet analysis technique is developed and used to study variable spectral features on top of broad emission lines in Wolf-Rayet stars. A decomposition of the signal in discrete structures allows one to look for scaling laws. Results from the study of two Wolf-Rayet stars suggest we are seeing the upper tail-end of a scaled distribution. This provides a test for turbulence models, and sets new constraints on theoretical wind models.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 82
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 87 (1998), S. 459-480 
    ISSN: 1573-1472
    Keywords: Coherence model ; Spatial coherence ; Turbulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Wind speed measurements from the test site at Rutherford Appleton Laboratory have been evaluated with respect to the spatial coherence function. The experimental arrangement provides coherence information for separation distances of 62, 80 and 102 m. These are at least three times greater than the measurement heights of 18 m and 18.7 m. Based on these experimental data and data published in the literature, different theoretical formulations are compared and a new, but simple, model for longitudinal and lateral coherence is proposed. At large separations the turbulent wind field is not isotropic, theoretical models to describe the coherence function for such distances are not available. The new model we propose builds on the classical exponential approach. It takes into account the influence of turbulence intensity and models the angular dependence of horizontal coherence. It is found that, for constant turbulence intensity, the lateral coherence decay becomes independent of the mean wind speed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 83
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 89 (1998), S. 285-316 
    ISSN: 1573-1472
    Keywords: Boundary layer ; Heterogeneous terrain ; Roughness length ; Surface fluxes ; Turbulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The aim of this work is to present experimentally evaluated effective roughnesses (zoe) of a partly forested landscape. Although the ratio of boundary-layer height to obstacle size was only of the order of 50, there still seemed to exist a height range of 75–200 m where surface-layer similarity was approximately valid. Attempts were made to use conventional wind profile analysis to evaluate zoe, but the small height range and the large number of variables initially led to unacceptable uncertainties. Fixing the displacement height zd, rather than fitting it, reduced the data scatter to an acceptable level. The profile-derived roughness lengths zop obtained in this way were in good agreement with previous work, and with an alternative roughness length estimate zof for which flux-derived profile parameters u* and θ* were used. This implies that the profile-derived roughnesses were consistent with the measured surface-layer momentum flux. Comparison of both roughness estimates also yielded an improved estimate of the displacement height. Besides this, the authors tested a landscape roughness evaluation method which makes use of the gustiness parameter Tu = σu/U in the surface layer. The results obtained by this method were in fair agreement with the profile-derived data. In previous work, the gustiness method was advocated because it could be used at relatively low levels, perhaps even within the roughness sub-layer. At the present measuring site, this was not the case as the gustiness method was only valid in an approximate way, and for a limited height range.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 84
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 77 (1996), S. 1-20 
    ISSN: 1573-1472
    Keywords: Turbulence ; Water vapor ; Turbulent flux ; Bulk Coefficient ; HEIFE ; Desert ; Similarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Observations of surface-layer turbulence and turbulent fluxes were made over a desert in northwestern China as a part of HEIFE (HEIhe river Field Experiment). These show that the normalized variations of the vertical wind component and of the air temperature obey Monin-Obukhov similarity well, especially in free convective conditions. However, the variations of specific humidity do not obey Monin-Obukhov similarity. Mean bulk transfer coefficients of sensible heat and momentum flux are obtained as functions of stability over a wide stability range from the observed data of turbulent fluxes and mast profiles. However, the bulk transfer coefficient for water vapor could not be obtained because of the large scatter of the data. In free convective conditions, the sensible heat flux was found to be approximately proportional to the 1.4 power of temperature difference between the surface and 20m. The bulk transfer coefficient of sensible heat is also obtained as a function of the bulk Richardson number for practical convenience.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 85
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 83 (1997), S. 285-309 
    ISSN: 1573-1472
    Keywords: Adjoint ; Data assimilation ; Turbulence ; Complex terrain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract This paper describes an adjoint method for data assimilation intoupstream boundary conditions of numerical modelsusing optimal control theory. Mathematical formalisms are given along with the numerical implementation of the schemein a column model of the atmospheric boundary layer. The optimized mean and turbulence profiles are used as an upstream solutionin a model of turbulent flow in complex terrain. To contrast thiswith other methods, two solutions for flow over an isolatedhill are calculated, one with an optimized upstream solution andone with a simple surface-layer formulation for the upstream solution.These two solutions are compared to observations and analytical theory. The adjoint optimization method is shown to producesolutions of flow in complex terrain that are substantively differentat the two solutions, with the optimized solution giving more accurate results.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 86
    ISSN: 1573-1472
    Keywords: Turbulence ; Canopies ; Temperature ramps ; Renewal models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Sensible heat, latent heat, and other scalar fluxes cannot be measuredwithin short dense canopies, e.g., straw mulches, with standard approachessuch as eddy correlation, Bowen ratio-energy balance, aerodynamic, andvariance methods. However, recently developed surface renewal models, thatare based on the fact that most of the turbulent transfer within and abovecanopies is associated with large-scale coherent eddies, which are evidentas ramp patterns in scalar time series, offer a feasible solution. Wepresent a new air renewal model that calculates sensible heat flux atdifferent heights within and above a canopy from the average cubictemperature structure function, sampled at a moderate rate, and measuredaverage friction velocity. The model is calibrated and tested with datameasured above and within a Douglas-fir forest and above a straw mulch andbare soil. We show that the model describes half-hour variations ofsensible heat flux very well, both within the canopy and roughnesssublayers and in the inertial sublayer, for stable and unstable atmosphericconditions. The combined empirical coefficient that appears in the modelhas an apparently universal value of about 0.4 for all surfaces andheights, which makes application of the model particularly simple. Themodel is used to predict daytime and nighttime sensible heat flux profileswithin the straw mulch and within a small bare opening in the mulch.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 87
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 84 (1997), S. 411-425 
    ISSN: 1573-1472
    Keywords: Trajectories ; Turbulence ; Dispersion ; Diffusion ; Numerical models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Among well-mixed multi-dimensional Lagrangian stochastic (LS) dispersion models, we observe that those in poorest agreement with observations produce ‘spiralling trajectories,’ with an associated reduction in dispersion. We therefore investigate statistics of increments dθ ' to the orientation θ'= arctan(W'/U') of the Lagrangian velocity-fluctuation vector – as a possible means to distinguish the better LS models within the well-mixed class. ‘Zero-spin’ models, having 〈 dθ'〉 = 0, are found to provide best agreement with observations. It is not clear however, whether imposition of the zero-spin property selects (in conjunction with the well-mixed condition) a unique model.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 88
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 85 (1997), S. 197-222 
    ISSN: 1573-1472
    Keywords: Turbulence ; Chemistry ; Closure ; Convective boundary layer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We study the interactions of chemistry and turbulent mixing of tracersin the convective boundary layer with a second-order closure model,including higher order chemistry terms. In order to limit the number of predictive equations we prescribe the profiles for ¯w¯Θ, ¯w¯θ ¯θ and the lengthscale l. However, for model validation we treat temperature and humidity asinert tracers, and compare the results with profiles observed during theAir Mass Transformation Experiment, and with similarity expressions for thesurface layer. We find good agreement of the mean profiles, but the (co-)variances are slightly underpredicted. Furthermore, the model usesdiagnostic equations expressing third moments of concentration in terms ofsecond moments and their vertical derivatives. They are compared withlarge-eddy model results, showing good agreement and, therefore, thesimplifications are justified. The model is applied to the transport of two gases subject to one bimolecular reaction. The importance of concentration correlations on themean transformation rate is studied. For two gases diffusing in oppositedirections we find for moderate and fast chemistry a 50% and90% decreased transformation rate due to the negatively correlatedconcentrations. These values are similar to large-eddy results of Schumannand Sykes et al. For two bottom-up tracers we find that the covariance ofboth reactive species is either positive or negative, increasing or reducingthe effective transformation rate depending on the Damköhler number (the ratio of the turbulent and the chemistry timescale). A significantdirect influence of chemistry on the flux divergence is found in bothcases. According to the model the effective transport to mid-levels of theboundary layer is increased when two reactive tracers diffuse in oppositedirections, and decreased in the case of two bottom-up tracers.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 89
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 86 (1998), S. 63-87 
    ISSN: 1573-1472
    Keywords: Stratocumulus ; Mass flux ; Lateral entrainment ; Turbulence ; Conditional sampling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A mass-flux approach is applied to observational data obtained in a convective boundary layer topped with stratocumulus clouds. The observational data were obtained from aircraft measurements during the Atlantic Stratocumulus Transition Experiment (ASTEX). A conditional sampling method is used to calculate average updraft and downdraft values. The vertical fluxes calculated with the mass-flux approach are found to be proportional to the real (measured) fluxes, with a proportionality factor being about 0.6. This value is predicted by theory for two variables having a joint Gaussian distribution function; proportionality factor = 2π-1 ≈ 0.637. The horizontal fractional entrainment and detrainment rates calculated from the data (ε ≈ 1–2 × 10-2 m-1) are an order of magnitude higher than the rates obtained by large eddy simulations for cumulus convection (ε ≈ 2–3 × 10-3 m-1) and two orders of magnitude higher than those used in modelling cumulus convection with a mass-flux scheme in an operational weather forecast model (ε ≈ 3 × 10-4 m-1). A numerical mass-flux model for the thermodynamics was developed and showed that results are in good agreement when compared with measured profiles of the liquid water content.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 90
    ISSN: 1573-1472
    Keywords: Turbulence ; Surface temperature ; Surface inhomogeneity ; Source area
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Turbulence characteristics, vertical profiles of wind velocity u(z) and air temperature T(z), and also spatial variations in steppe surface radiation temperature Tr(x) are measured simultaneously. A marked effect of Tr(x) characteristics on the turbulence characteristics and T(z) profiles is observed in the lower part of the atmospheric surface layer. We suggest that variability in Tr(x) noticeably influences the surface-layer temperature field and leads to scatter in the values of the universal functions obtained by different authors; effects of Tr(x) are not accounted for in similarity theory. The introduction of the value of temperature zero-plane displacement dT in the calculation formulae (to determine temperature flux) noticeably improves the agreement between calculated and measured (by eddy-correlation method) results. The influence of footprint (or Source Area) on the obtained results leads to noticeable scatter in the data obtained from measurements of atmospheric turbulence.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 91
    ISSN: 1573-1472
    Keywords: Turbulence ; Convective boundary layer ; Clear air radar observations ; Coherent organizations ; Radar-aircraft joint observations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The scientific objective of the TRAC experiment (Turbulence Radar Aircraft Cells) was to investigate the respective roles played by small-scale turbulence and coherent structures in the vertical transfer within the atmospheric boundary layer (ABL). Field research held in June 1993 in France was based on coupled aircraft and Doppler radar measurements. The results discussed here are mainly focused on the evaluation of the performance of the radar in the 3D description of the clear air ABL, which was the technical goal of TRAC. During the experiment, the radar was able to provide continuous and coherent echo fields over a range of several tens of kilometres, extending up to about 3 km. Good agreement was obtained in the ABL between the radar-derived turbulent quantities and airborne measurements. As depicted by the reflectivity fields, coherent organizations were found to be a common feature of the eleven ABL cases analyzed. These organizations evolved during the day between a banded structure and a cellular pattern. A very weak correlation was found between the reflectivity field and the atmospheric parameters measured by the aircraft. However, in terms of characteristic scale, the reflectivity field appeared to be strongly related to the water vapour field. The inhomogeneity induced by the coherent circulations questions the representativity of one-dimensional sampling of these 3D fields and suggests the need to adapt the traditional statistical approach of the ABL.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 92
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 86 (1998), S. 233-256 
    ISSN: 1573-1472
    Keywords: Lidar ; Remote sensing ; Turbulence ; Velocity statistics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Coherent Doppler lidar measurements of wind statistics in the boundary layer are presented. The effects of the spatial averaging by the lidar pulse are removed using theoretical corrections and computer simulations. This permits unbiased estimates of velocity variance, spatial velocity structure functions, energy dissipation rate, and other point statistics of the velocity field.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 93
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 86 (1998), S. 333-344 
    ISSN: 1573-1472
    Keywords: Turbulence ; Dispersion model ; Non-uniqueness ; Plant canopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Lagrangian stochastic models, quadratic in velocity and satisfying the well-mixed condition for two-dimensional Gaussian turbulence, are used to make predictions of scalar dispersion within a model plant canopy. The non-uniqueness associated with satisfaction of the well-mixed condition is shown to be non-trivial (i.e. different models produce different predictions for scalar dispersion). The best agreement between measured and predicted mean concentrations of scalars is shown to be obtained with a small sub-class of ‘optimal’ models. This sub-class of ‘optimal’ models includes Thomson's model (J. Fluid Mech. 180, 529–556, 1987), the simplest model that satisfies the well-mixed condition for Gaussian turbulence, but does not include two other models identified recently as being in optimal agreement with the measured spread of tracers in a neutral boundary layer. It is therefore demonstrated that such models are not universal, i.e. applicable to a wide range of flows without readjustment of model parameters. Predictions for scalar dispersion in the model plant canopy are also obtained using the model of Flesch and Wilson (Boundary-Layer Meteorol. 61, 349–374, 1992). It is shown that, when used with a Gaussian velocity distribution or a maximum-missing-information velocity distribution, which accounts for the measured skewness and kurtosis of velocity statistics, the agreement between predictions obtained using the model of Flesch and Wilson and measurements is as good as that obtained using Thomson's model.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 94
    ISSN: 1573-1472
    Keywords: Lagrangian decorrelation time scales ; Structure function constant ; Turbulence ; Lagrangian spectrum constant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A new method for deriving the Lagrangian decorrelation time scales for inhomogeneous turbulence is described. The expression for the time scales here derived for the convective boundary layer is compared to those estimated by Hanna during the Phoenix experiment. Then the values of C0, the Lagrangian velocity structure function constant, and of Bi, the Lagrangian velocity spectrum constant, were evaluated from the Eulerian velocity spectra and from the Lagrangian time scales derived, under unstable conditions, from Taylor's statistical diffusion theory. The numerical coefficient of the lateral and vertical Lagrangian spectra in the inertial subrange was found equal to 0.21, in good agreement with previous experimental estimates.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 95
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 87 (1998), S. 1-25 
    ISSN: 1573-1472
    Keywords: Kites ; Atmospheric measurements ; Turbulence ; Profiling ; Ozone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract This paper presents the capabilities and limitations of using state-of-the-art kites for atmospheric research. A brief historical review of the subject is first presented, followed by an outline of the current status of kite-borne measurement technology. The utility of the technique is then illustrated by presenting a series of recent measurements made using kite-borne technology. A summary of the advantages and limitations of kite-based measurements relative to other technologies is provided for reference.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 96
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 91 (1999), S. 227-257 
    ISSN: 1573-1472
    Keywords: Coastal boundary layer ; Initialisation ; Mesoscale model ; Sea model breeze ; Thermal internal boundary layer ; Turbulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A numerical two-dimensional-mesoscale model with a level 1.5 closure scheme for turbulence is described. The model is used to simulate the boundary layer over coastal complex terrain. Meteorological data available from the Øresund land-sea-land terrain experiment are used to study the performance of the model. The model could simulate generally observed complexities in the mean wind and temperature fields. Internal boundary layers over the water and land surfaces were identified by the height of lowest value in the turbulence kinetic energy profile and this showed good agreement with radiosonde (RS) observations. Some disagreements with the data were also noticed, especially near the surface. The wind speed was over-predicted. Attempts were made to improve the model performance by adopting different schemes for model initialisation. Results showed that initialisation with an early model start time and observed wind profile near the inflow boundary improved the performance. The wind speed over-prediction could be further minimised by using a more realistic objective initialisation scheme. The problem centred around the proper estimation of the turbulent diffusion coefficient K through the closure scheme. Despite using the most popular empirical relationships in the level 1.5 closure scheme, these differences persisted. While this needs further investigation, the present model can be used to supply wind fields for practical purposes such as air pollution calculations.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 97
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 91 (1999), S. 483-493 
    ISSN: 1573-1472
    Keywords: Turbulence ; Flow distortion ; Sonic anemometers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We carried out measurements to test a simple theory of the effect of probe-induced flow distortion on turbulence measurements. We used two three-component sonic anemometers mounted 1.8m apart at a height of 6.7 m. Behind one was a horizontal circular cylinder of radius 0.15 m and length 1.2 m, chosen to model two-dimensional probe-induced flow distortion in the limit where the scale of the turbulence is very large compared to the scale of the probe. The second sonic anemometer measured the undistorted flow. The measured flow-distortion effects on the Reynolds shearing stress and the variances of streamwise and vertical velocity agree well with the theory.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 98
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 92 (1999), S. 37-63 
    ISSN: 1573-1472
    Keywords: Energy balance ; Glacier ; Katabatic flow ; Stable boundary layer ; Turbulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Turbulence measurements performed in a stable boundary layer over the sloping ice surface of the Vatnajökull in Iceland are described. The boundary layer, in which katabatic forces are stronger than the large-scale forces, has a structure that closely resembles that of a stable boundary layer overlying a flat land surface, although there are some important differences. In order to compare the two situations the set-up of the instruments on an ice cap in Iceland was reproduced on a flat grass surface at Cabauw, the Netherlands. Wind speed and temperature gradients were calculated and combined with flux measurements made with a sonic anemometer in order to obtain the local stability functions φm and φh as a function of the local stability parameter z/L. Unlike the situation at Cabauw, where φm was linear as a function of z/L, in the katabatically forced boundary layer, the dependence of φm on stability was found to be non-linear and related to the height of the wind maximum. Thermal stratification and the depth of the stable boundary layer however seem to be rather similar under these two different forcing conditions. Furthermore, measurements on the ice were used to construct the energy balance. These showed good agreement between observed melt and components contributing to the energy balance: net radiation (supplying 55% of the energy), sensible heat flux (30%) and latent heat flux (15%). Local sources and sinks in the turbulent kinetic energy budget are summed and indicate a reasonable balance in near-neutral conditions but not in more stable situations. The standard deviation of the velocity fluctuations σu, σv, and σw, can be scaled satisfactorily with the local friction velocity u* and the standard deviation of the temperature fluctuation σθ with the local temperature scale θ*.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 99
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 92 (1999), S. 165-183 
    ISSN: 1573-1472
    Keywords: Coherent structures ; Turbulence ; Surface layer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Multi-level turbulent wind data from the Risø Air-Sea Experiments (RASEX) were used to examine the structure of large-scale motions in the marine atmospheric surface layer. The quadrant technique was used to identify flux events (ejections/sweeps). Ejections, which appear to occur in groups, are seen to occur first at the upper level, moving successively to lower levels with small time delays. A strong correlation between events at different heights suggests that they may all be part of a single large structure. Cross-correlation between velocity signals was used to estimate orientation of the structure using Taylor's hypothesis. The inclination of this structure is shallow (≃ 15°) near the surface and increases with height. Spatial representations of the fluctuating wind vectors show a structure that is strikingly similar to conceptual models of transverse vortices and shear layers seen in laboratory flows and direct numerical simulation (DNS) of low Reynolds number flows. Spatial visualization of velocity fluctuations during other time periods and conditions clearly shows the existence of shear layers, transverse vortices, plumes, and downdrafts of various sizes and strengths. A quantitative analysis shows an increase in the frequency of shear related events with increasing wind speed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 100
    ISSN: 1573-1472
    Keywords: Closure models ; Drizzle ; Entrainment ; Large Eddy Simulation ; Observations ; Stratocumulus ; Turbulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract As part of the EUropean Cloud REsolving Modelling (EUCREM) model intercomparison project we compared the properties and development of stratocumulus as revealed by actual observations and as derived from two types of models, namely three-dimensional Large Eddy Simulations (LES) and one-dimensional Single Column Models (SCMs). The turbulence, microphysical and radiation properties were obtained from observations made in solid stratocumulus during the third flight of the first 'Lagrangian' experiment of the Atlantic Stratocumulus Transition Experiment (ASTEX). The goal of the intercomparison was to study the turbulence and microphysical properties of a stratocumulus layer with specified initial and boundary conditions. The LES models predict an entrainment velocity which is significantly larger than estimated from observations. Because the observed value contains a large experimental uncertainty no definitive conclusions can be drawn from this. The LES modelled buoyancy flux agrees rather well with the observed values, which indicates that the intensity of the convection is modelled correctly. From LES it was concluded that the inclusion of drizzle had a small influence (about 10%) on the buoyancy flux. All SCMs predict a solid stratocumulus layer with the correct liquid water profile. However, the buoyancy flux profile is poorly represented in these models. From the comparison with observations it is clear that there is considerable uncertainty in the parametrization of drizzle in both SCM and LES.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...