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
  • Other Sources  (60)
  • Articles (OceanRep)  (60)
  • American Meteorological Society  (59)
  • ASLO (Association for the Sciences of Limnology and Oceanography)
  • Springer Nature
  • 1995-1999  (60)
  • 1
    facet.materialart.
    Unknown
    American Meteorological Society
    In:  Bulletin of the American Meteorological Society, 78 (12). pp. 2771-2777.
    Publication Date: 2019-03-07
    Description: A review is given of the meaning of the term “El Niño” and how it has changed in time, so there is no universal single definition. This needs to be recognized for scientific uses, and precision can only be achieved if the particular definition is identified in each use to reduce the possibility of misunderstanding. For quantitative purposes, possible definitions are explored that match the El Niños identified historically after 1950, and it is suggested that an El Niño can be said to occur if 5-month running means of sea surface temperature (SST) anomalies in the Niño 3.4 region (5°N–5°S, 120°–170°W) exceed 0.4°C for 6 months or more. With this definition, El Niños occur 31% of the time and La Niñas (with an equivalent definition) occur 23% of the time. The histogram of Niño 3.4 SST anomalies reveals a bimodal character. An advantage of such a definition is that it allows the beginning, end, duration, and magnitude of each event to be quantified. Most El Niños begin in the northern spring or perhaps summer and peak from November to January in sea surface temperatures.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Publication Date: 2018-04-06
    Description: On 24 and 25 October 1995, high-resolution oceanographic measurements were carried out in the Strait of Messina by using a towed conductivity-temperature-depth chain and a vessel-mounted acoustic Doppler current profiler. During the period of investigation the surface water of the Tyrrhenian Sea north of the strait sill was heavier than the surface water of the Ionian Sea south of the strait sill. As a consequence, during northward tidal flow surface water of the Ionian Sea spread as a surface jet into the Tyrrhenian Sea, whereas during southward tidal flow heavier surface water of the Tyrrhenian Sea spread, after having sunk to a depth of about 100 m, as a subsurface jet into the Ionian Sea. Both jets had the form of an internal bore, which finally developed into trains of internal solitary waves whose amplitudes were larger north than south of the strait sill. These measurements represent a detailed picture of the tidally induced internal dynamics in the Strait of Messina during the period of investigation, which contributes to elucidate several aspects of the general internal dynamics in the area: 1) Associated with the tidal flow are intense water jets whose equilibrium depth strongly depends on the horizontal density distribution along the Strait of Messina; 2) although climatological data show that a large horizontal density gradient in the near-surface layer along the Strait of Messina exists, its reversal can occur; 3) fluctuations in the larger-scale circulation patterns that determine the inflow of the modified Atlantic water into the Eastern Mediterranean Sea can be responsible for this reversal. As the tidally induced internal waves reflect the variability in the horizontal density distribution along the Strait of Messina, it is suggested that from the analysis of synthetic aperture radar imagery showing sea surface manifestations of internal waves in this area fluctuations of larger-scale circulation patterns in the Mediterranean Sea can be inferred.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    facet.materialart.
    Unknown
    American Meteorological Society
    In:  Journal of Atmospheric and Oceanic Technology, 15 . pp. 1051-1059.
    Publication Date: 2018-07-04
    Description: A new optical disdrometer has been developed that is optimized for use in high wind speeds, for example, on board ships. The minimal detectable size of droplets is 0.35 mm. Each drop is measured separately with regard to its size and residence time within the sensitive volume. From the available information, the drop size distribution can be calculated with a resolution of 0.05 mm in diameter either by evaluation of the residence time of drops or by drop counting knowing the local wind. Experience shows that using the residence time leads to better results. Rain rates can be determined from the droplet spectra by assuming terminal fall velocity of the drops according to their size. Numerical modeling of disdrometer measurements has been performed, allowing the study of the effect of multiple occupancy of the sensitive volume and grazing incidences on disdrometer measurements. Based on these studies an iterative procedure has been developed to eliminate the impact of these effects on the calculated drop size distributions. This technique may also be applied to any other kind of disdrometer. Long-term simultaneous measurements of the disdrometer and a conventional rain gauge have been used to validate this procedure.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Publication Date: 2018-04-06
    Description: A new numerical two-layer model is presented, which describes the generation of internal tidal bores and their disintegration into internal solitary waves in the Strait of Messina. This model is used to explain observations made by the synthetic aperture radar (SAR) from the European Remote Sensing satellites ERS 1 and ERS 2. The analysis of available ERS 1/2 SAR data of the Strait of Messina and adjacent sea areas show that 1) northward as well as southward propagating internal waves are generated in the Strait of Messina, 2) southward propagating internal waves are observed more frequently than northward propagating internal waves, 3) sea surface manifestations of southward as well as northward propagating internal waves are stronger during periods where a strong seasonal thermocline is known to be present, 4) southward propagating internal bores are released from the sill between 1 and 5 hours after maximum northward tidal flow and northward propagating internal bores are released between 2 and 6 hours after maximum southward tidal flow, and 5) the spatial separation between the first two internal solitary waves of southward propagating wave trains is smaller in the period from July to September than in the period from October to June. The numerical two-layer model is a composite of two models consisting of 1) a hydrostatic “generation model,” which describes the dynamics of the water masses in the region close to the strait’s sill, where internal bores are generated, and 2) a weakly nonhydrostatic “propagation model,” which describes the dynamics of the water masses outside of the sill region where internal bores may disintegrate into internal solitary waves. Due to a technique for movable lateral boundaries, the generation model is capable of simulating the dynamics of a lower layer that may intersect the bottom topography. The proposed generation–propagation model depends on one space variable only, but it retains several features of a fully three-dimensional model by including a realistic channel depth and a realistic channel width. It is driven by semidiurnal tidal oscillations of the sea level at the two open boundaries of the model domain. Numerical simulations elucidate several observed characteristics of the internal wave field in the Strait of Messina, such as north–south asymmetry, times of release of the internal bores from the strait’s sill, propagation speeds, and spatial separations between the first two solitary waves of internal wave trains.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    facet.materialart.
    Unknown
    American Meteorological Society
    In:  Journal of Physical Oceanography, 28 . pp. 1107-1129.
    Publication Date: 2018-04-06
    Description: On the basis of the collection of individual marine observations available from the Comprehensive Ocean–Atmosphere Data Set, major parameters of the sea state were evaluated. Climatological fields of wind waves and swell height and period, as well as significant wave height and resultant period are obtained for the North Atlantic Ocean for the period from 1964 to 1993. Validation of the results against instrumental records from National Data Buoy Center buoys and ocean weather station measurements indicate relatively good agreement for wave height and systematic biases in the visually estimated periods that were corrected. Wave age, which is important for wind stress estimates, was evaluated form wave and wind observations. The climatology of wave age indicates younger waves in winter in the North Atlantic midlatitudes and Tropics. Wave age estimates were applied to the calculations of the wind stress using parameterizations from field experiments. Differences between wave-age-based and traditional estimates are not negligible in wintertime in midlatitudes and Tropics where wave-induced stress contributes from 5% to 15% to the total stress estimates. Importance of the obtained effects for ocean circulation and climate variability is discussed.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    facet.materialart.
    Unknown
    American Meteorological Society
    In:  Journal of Physical Oceanography, 29 . pp. 145-157.
    Publication Date: 2018-04-06
    Description: As a contribution to the WOCE Deep Basin Experiment, an array of current meters with individual record lengths exceeding ii years was set across the southern boundary of the Brazil Basin between early 1991 and early 1996. The array spanned the Santos Plateau, the Vema Channel, and the Hunter Channel, all areas believed to be important for transport of Antarctic Bottom Water between the Argentine and Brazil Basins. From the combination of geostrophic velocities computed from hydrographic stations and those directly measured, the total transport of bottom water (potential temperature below 2 degrees C) is estimated to be about 6.9 Sv (Sv = 10(6) m(3) s(-1)) northward, with about 4 Sv coming through the Vema Channel and the remainder through the Hunter Channel. Properties of the eddy field are also discussed. Eddy energy levels and their spatial distribution are similar to comparable regimes in the North Atlantic. Integral timescales vary from a few days to several weeks with distance from the Brazil Current and the western boundary. The eddy heat Bur is in the same direction as the heat advection by the mean flow but considerably smaller.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    facet.materialart.
    Unknown
    American Meteorological Society
    In:  Journal of Physical Oceanography, 25 (10). pp. 2444-2457.
    Publication Date: 2018-04-05
    Description: Surface heat and freshwater fluxes from the Comprehensive 0cean-Atmosphere Data Set are revised and used diagnostically to compute air-sea transformation rates on density, temperature, and salinity classes over the domain of the data. Maximum rates occur over the warmest water and over mode waters, which are the dominant result of air-sea interaction. Transformation in different is accordingly distinguished by temperature and salinity, just as water masses in different oceans are so distinguished. Over the entire domain, to about 30°S, approximately 80×106 m3 s−1 of warm cool water are transformed by air-sea fluxes, on annual average. Calculations for several seas in the North Atlantic, where deep water is thought to originate, we also presented.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    facet.materialart.
    Unknown
    American Meteorological Society
    In:  Journal of Physical Oceanography, 27 . pp. 381-402.
    Publication Date: 2018-04-06
    Description: Parametric representations of oceanic geostrophic eddy transfer of heat and salt are studied ranging fromhorizontal diffusion to the more physically based approaches of Green and Stone (GS) and Gent and McWilliams(GM). The authors argue for a representation that combines the best aspects of GS and GM: transfer coefficientsthat vary in space and time in a manner that depends on the large-scale density fields (GS) and adoption of atransformed Eulerian mean formalism (GM). Recommendations are based upon a two-dimensional (zonally orazimuthally averaged) model with parameterized horizontal and vertical fluxes that is compared to three-dimensional numerical calculations in which the eddy transfer is resolved. Three different scenarios are considered: 1) a convective “chimney” where the baroclinic zone is created by differential surface cooling; 2) spindownof a frontal zone due to baroclinic eddies; and 3) a wind-driven, baroclinically unstable channel. Guided bybaroclinic instability theory and calibrated against eddy-resolving calculations, the authors recommend a formfor the horizontal transfer coefficient given by where Ri = f2N2/M4 is the large-scale Richardson number and f is the Coriolis parameter; M2 and N2 are measuresof the horizontal and vertical stratification of the large-scale flow, l measures the width of the baroclinic zone,and α is a constant of proportionality. In the very different scenarios studied here the authors find α to be a“universal” constant equal to 0.015, not dissimilar to that found by Green for geostrophic eddies in the atmosphere. The magnitude of the implied k, however, varies from 300 m2 s−1 in the chimney to 2000 m2 s−1 inthe wind-driven channel.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    facet.materialart.
    Unknown
    American Meteorological Society
    In:  Journal of Atmospheric and Oceanic Technology, 16 . pp. 133-145.
    Publication Date: 2018-07-04
    Description: The reliability of the Comprehensive Ocean–Atmosphere Dataset (COADS) Release 1a 2° monthly winds is tested by comparing it with instrumental measurements in the northwest Atlantic from 1981 to 1991. The instrumental dataset contains anemometer measurements of a very high homogeneity and quality, which were taken by six research sister ships with known anemometer heights in the northwest Atlantic. Special data processing was made with instrumental samples to provide compatibility with the COADS winds. Comparison shows overestimation of the COADS winds in the low ranges and underestimation of the strong and moderate winds. Application of the alternative equivalent Beaufort scales does not remove this bias and makes it even more pronounced. Thus, the conclusion is made that the disagreement obtained results primarily from the uncertainties of anemometer measurements in COADS, especially from the incorrect evaluation of the true wind. Instrumental data also do not indicate significant long-term interannual changes, which are pronounced in the COADS dataset for the 1980s. Some regional features of the comparison are discussed.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    facet.materialart.
    Unknown
    American Meteorological Society
    In:  Bulletin of the American Meteorological Society, 79 (10). pp. 2033-2058.
    Publication Date: 2016-09-07
    Description: In the autumn of 1996 the field component of an experiment designed to observe water mass transformation began in the Labrador Sea. Intense observations of ocean convection were taken in the following two winters. The purpose of the experiment was, by a combination of meteorological and oceanographic field observations, laboratory studies, theory, and modeling, to improve understanding of the convective process in the ocean and its representation in models. The dataset that has been gathered far exceeds previous efforts to observe the convective process anywhere in the ocean, both in its scope and range of techniques deployed. Combined with a comprehensive set of meteorological and air-sea flux measurements, it is giving unprecedented insights into the dynamics and thermodynamics of a closely coupled, semienclosed system known to have direct influence on the processes that control global climate.
    Type: Article , PeerReviewed
    Format: text
    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...