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  • Springer  (491,730)
  • 1985-1989  (267,449)
  • 1980-1984  (224,281)
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  • 101
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    Pure and applied geophysics 119 (1980), S. 474-490 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
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  • 102
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    Pure and applied geophysics 119 (1980), S. 510-514 
    ISSN: 1420-9136
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  • 103
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    Pure and applied geophysics 119 (1980), S. 515-537 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Recent advances in the use of dynamical and statistical models to forecast the weather are described. High resolution physical-mathematical models can now predict the development of synoptic weather systems in great detail for a few days ahead, while large-scale phenomena like blocking can be predicted for about a week or more. The local forecasting problem is presently being attacked by statistical- and meso-scale models using the large-scale predictions as input parameters. Very encouraging results have been obtained to predict the local weather, in particular when the local weather is influenced by topography and the underlying surface.
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  • 104
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    Pure and applied geophysics 119 (1980), S. 538-547 
    ISSN: 1420-9136
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  • 105
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    Pure and applied geophysics 119 (1980), S. 558-576 
    ISSN: 1420-9136
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  • 106
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    Pure and applied geophysics 119 (1980), S. 548-557 
    ISSN: 1420-9136
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  • 107
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    Pure and applied geophysics 119 (1980), S. 577-593 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In recent years there has been much progress in describing and understanding the detailed dynamical and microphysical structure of frontal precipitation systems. In this article we consider phenomena on a hierarchy of scales: the broad synoptic-scale flows in mid-latitude depressions, the mesoscale patterns of precipitation, the nature and origin of convection at the surface and aloft, and the microphysical properties of the resulting precipitation. The influence of orography is also briefly discussed.
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  • 108
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    Pure and applied geophysics 119 (1980), S. 798-808 
    ISSN: 1420-9136
    Keywords: Solar-terrestrial relationship ; Effect of sunspot numbers on monthly temperature/precipitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Spectral analyses were made of derived area-index series of areas subject to extreme temperatures and precipitation as well as cross-spectral analyses of the area-index series with double sunspot cycle (Zurich) numbers. Superposed epoch analyses also were made of area-index series versus various double-sunspot cycle phases. Area series for wet and dry Junes, warm Junes, defined June drought, and warm Januaries all show statistically significant double sunspot cycle (∼21 year) periodicities. The 21-year cycle of above-normal June precipitation is most striking and has not received previous recognition.
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  • 109
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    Pure and applied geophysics 119 (1980), S. 809-815 
    ISSN: 1420-9136
    Keywords: Cloud dynamics ; Mixing process in cumulus clouds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract An examination is made of the hypothesis that internal cloud properties are determined by the mixing of dry air from above the cloud top and cloud base air in such a way that the mixture is neutrally buoyant with respect to the clear air environment at each level. It is concluded that the resulting mixture is much drier than is actually observed. Comments are made about observed cloud properties which need to be taken into account in any model of the mixing process.
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  • 110
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    Pure and applied geophysics 119 (1980), S. 816-819 
    ISSN: 1420-9136
    Keywords: Cloud dynamics ; Mixing processes in cumulus clouds
    Source: Springer Online Journal Archives 1860-2000
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  • 111
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    Pure and applied geophysics 119 (1980), S. 820-830 
    ISSN: 1420-9136
    Keywords: Riming of ice crystals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Riming growth of ice particles is simulated by numerically solving the stochastic collection equations, simultaneously considering coagulation of water droplets. By introducing a special criterion which defines the habit of a riming particle, the influence of this habit on the growth of several kinds of ice particles assumed to be formed during riming was investigated. It was found that (i) hexagonal rimed ice plates are growing more efficiently than lump graupel or rimed columns, (ii) the use of different collection kernels for the lump graupel evolution leads to widely differing results and that (iii) the time dependent decrease of liquid water substance and the size of the resulting ice particles were more strongly influenced by the initial ice crystal concentration than by the initial ice crystal size and the habit of the ice particles. By decreasing the number density of ice crystals gradually a critical ice crystal concentration was found at which the present liquid water was not completely consumed by the riming process even after 1800 s model time, causing large drops of radii 〉100 μm to be formed in appreciable concentrations.
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  • 112
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    Pure and applied geophysics 119 (1980), S. 831-840 
    ISSN: 1420-9136
    Keywords: Extinction ; Radiation ; Turbidity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Helicopter measurements of solar irradiance and meteorological data within the atmospheric boundary-layer were made in Lagos during February 1979. Filter samples of aerosols were collected both during flight in February 1979 and at ground level in December 1978. Profile data on spectral aerosol optical depth were obtained and, from these, the aerosol extinction coefficient at two wavelengths (0.5 and 0.88 μm) were calculated. Precipitable water was low and was contained mainly within the 750 m layer above ground, suggesting the establishment of a deep unstable boundary layer. Calculated channel energy depletions by aerosols show that, within the first 750 m of the surface, the 0·88 μm might be more efficient at attenuating solar energy than 0·5 μm. The lagoon (maritime) aerosol sample indicated a more monodisperse size-distribution than the dusty harmattan aerosol sample.
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  • 113
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    Pure and applied geophysics 119 (1980), S. 888-892 
    ISSN: 1420-9136
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  • 114
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    Pure and applied geophysics 119 (1981), S. 966-977 
    ISSN: 1420-9136
    Keywords: Streamer interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Investigation was carried out to study the interaction of positive streamers with charged and uncharged drops in a vertical electric field configuration. Results obtained for vertical and horizontal positions of the photographic films show that streamer interactions with neutral and negative drops are similar and further confirmed earlier results byPhelps (1972). It showed that indirect streamer interaction with droplets is effected by branches being sent to the drops from the main channel. The visibility of the branches on the Lichtenberg figures and the degree of interaction of streamers with drops depend on the drop size, its initial charge and shape, and/or the separation of the drops from the main channel. Suppression of streamer propagation among the positively charged drops was observed.
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  • 115
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    Pure and applied geophysics 119 (1981), S. 978-989 
    ISSN: 1420-9136
    Keywords: Ozone maxima ; Dry deposition ; Local cross-valley wind system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The diurnal cycle of ozone at the surface and within the PBL is examined. It is concluded that the intrusion of air masses from ozone-rich layers in the lower troposphere results in late evening ozone maxima observed at ground stations on mountain slopes as well as within distinct layers of the PBL above the valley bottom. The ozone-rich layers are assumed to exist due to meso- or large-scale horizontal transport of smog air masses and a local cross-valley wind system is shown to be responsible for the occurrence of the intrusion processes.
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  • 116
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    Pure and applied geophysics 119 (1981), S. 934-965 
    ISSN: 1420-9136
    Keywords: Condensation ; effect of entrainment on ; Cloud drop formation ; effect of entrainment on
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract It has been speculated for many years that the development of the droplet spectra in cloud is probably influenced by mixing processes. Various theoretical attempts to broaden the droplet spectra by mixing parcels with different velocity histories has shown that that particular effect is small. Similarly, very simpleuniform entrainment procedures did not lead to cloud drop size spectra which were broad enough, although by producing cloud drop size distributions with a double mode these models did substantially improve the drop size spectra of earlier adiabatic models which only exhibited a single mode. Recently a model based on entraining entities representing moving parcels of cloud air within the cloud was detailed byTelford andChai (1980). This study showed that the mixing in of dry air at cumulus turrets could lead to vertical cycling of diluted parcels, and that this cycling, with continual entrainment across the parcel boundaries, will produce much larger drops, as well as smaller drops of all sizes, in the droplet spectra. The ‘entity entrainment’ concept studied there appears to apply to the observations of stratus cloud discussed in this paper. This paper presents data taken in marine stratus off the California coast which give a particularly clear example of how such droplet spectra modification occurs in practice. Both large drops, and the spread of the spectra to smaller sizes, occur in relation to other variables in such a way as to be consistent with an entity entrainment explanation, with no other obvious possibility. In a marine stratus cloud just over 200 m thick and many tens of miles in extent we find clear evidence that dry air is mixing in at cloud tops. Strong vertical motion is to be found in the cloud, large sized drops are found in cloud parcels where the mixing gives lower droplet concentrations, and there is evidence that newly formed cloud parcels are warmer and contain many more smaller droplets. The observations show that immediately following entrainment of dry air drop diameters are not reduced appreciably, but, in the same parcels, drop concentrations have been reduced by a factor of ten or more. Further down in the cloud big drops, able to start growth by coalescence, are found associated with low total droplet concentrations. Overall, it seems likely from the consideration of these observations that the formation of the large drops which lead to precipitation processes in clouds depends critically on the mixing in of dry air at cloud tops, and very little on the size of the small drops resulting from the condensation nucleus counts. As a conclusion it appears reasonable to state that if entrainment occurs at cloud tops, then big drops will be formed!
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  • 117
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    Pure and applied geophysics 119 (1981), S. 1024-1036 
    ISSN: 1420-9136
    Keywords: Electromagnetic scattering ; VLF electromagnetic prospection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract FollowingDmitriev (1960) a rigorous theoretical solution for the problem of scattering by a perfectly conducting inclined half-plane buried in a uniform conductive half-space has been obtained for plane wave excitation. The resultant integral equation for the Laplace transform of scattering current in the half-plane is solved numerically by the method of successive approximation. The scattered fields at the surface of the half-space are found by integrating the half-space Green's function over the transform of the scattering current. The effects of depth of burial and inclination, of the half-plane on the scattered fields are studied in detail. An increase in the depth of burial leads to attenuation of the fields. Inclination introduces asymmetry in the field profiles beside affecting its magnitude. Depth of exploration is greater for quadrature component. An interpretation scheme based on a phasor diagram is presented for the VLF-EM method of exploration for rich vein deposits in a conductive terrain.
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  • 118
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    Pure and applied geophysics 119 (1981), S. 1077-1092 
    ISSN: 1420-9136
    Keywords: Seismic hazard estimation ; Bohemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The contribution reviews basic concepts of earthquake hazard assessment for sites of nuclear power plants. Taking into account the delineation of earthquake source regions, intensity-frequency relations, upper intensity thresholdsI max and intensity attenuation curves, we determine the seismic hazard for a site in south Bohemia and calculated the quantities defining the seismic hazard, i.e. return period in years, probability of exceedance for different intensities and different periods of interest. The adopted procedure has some limitations due to the poor definition of seismogenic zones (boundaries,N(I),I max) and lack of strong motion observations in Central Europe.
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  • 119
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    Pure and applied geophysics 119 (1981), S. 1125-1133 
    ISSN: 1420-9136
    Keywords: Seismicity and crustal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Focal solutions of four strong earthquakes and P signals of twenty-four smaller shocks of the active Mur-Mürz Valley, the Semmering Pass and the Vienna Basin. An ‘equivalent slip rate’ of 0.03 This feature agrees with the model of a subsiding Pannonian Basin. An ‘equivalent slip rate’ of 0.03 cm/year is roughly estimated from earthquake data 1903–1978. This rate does not include the creep rate, but it gives an idea of the magnitude of speed of geological processes in this area. Refraction seismic data from the Alpine Longitudinal Profile 75 shows a low velocity zone in the upper crust of the seismic active East Alpine area but not in the aseismic part of the Pannonian Basin. The eastern margin of the Eastern Alps and the Carpathians limits the Pannonian Basin, which has a special and interesting geological history. Many authors (Szadezky-Kardoss, 1966;Stegena, Ceszy andHorvàth, 1975) presented models of the genesis of the Pannonian Basin. They apply the concept of the ‘mantle diapirs’ to explain the following facts: subsiding of the Pannonian Plate in comparison to the Alps, high terrestrial heat flow within the Pannonian Plate, decrease of the Moho depth from 40 km below the Eastern border of the Alps to 27 km below the Pannonian Basin. They claim that the Alpine-Carpathian interarc and basin represent the final stage of an orogenetic system where ‘subcrustal erosion’ leads to a thinning of the crust. Consequently the surface subsides and is covered by young sediments. They proved that this subsidence and sedimentation is more or less in isostatic equilibrium. The aim of this paper is to provide new arguments using focal solutions and refraction seismic investigations.
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  • 120
    ISSN: 1420-9136
    Keywords: Caucasus ; Three-dimensional seismic modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract This paper deals with a procedure of a joint analysis of seismic data from earthquakes and those obtained by DSS. The DSS data are used as a first approximation to construct a two-dimensional model of the medium made up of individual blocks. These models serve as a basis when constructing specific three-dimensional travel-time curves. These travel-time curves are further used for the calculation of hypocenter parameters in a laterally inhomogeneous block medium. The hypocenter field and the travel times obtained are input data for the computation of three-dimensional fields of velocities in earthquake focal zones. Results of applying the proposed procedure to the Caucasus region are presented.
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  • 121
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    Pure and applied geophysics 120 (1982), S. 79-94 
    ISSN: 1420-9136
    Keywords: Monsoon ; Rainfall ; Tropical meteorology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The paper deals with an application of a stochastic model to the frequency and duration of precipitation events. With the aid of the model, the magnitudes ofmth highest rainfall amount in 24 hours' duration with 97.5% probability are obtained for various climatic regimes over a tropical monsoon region. There is good agreement between them-day minimum rainfall estimated through the model and the observed value. The model satisfactorily explains the frequency of the extreme rainfall event.
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  • 122
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    Pure and applied geophysics 120 (1982), S. 249-260 
    ISSN: 1420-9136
    Keywords: Correlation function ; Interpolation ; Network design
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The study examines the correlation function of tropical monsoon rainfall on monthly, seasonal and annual time scales and obtains the relationship between this function and the distance. The area selected for study is Vidarbha with a fairly dense network of rain gauges. Vidarbha is a meteorological sub-division of the state of Maharashtra in India. Utilizing the relationship between the correlation function of the rainfall field and the distance, the errors of optimum interpolation of rainfall at a point have been computed by applying the method of optimum interpolation byGandin (1970). Relationships between the errors of interpolation and distance have been evaluated and from this the maximum spacing allowed between rain gauges for a specified tolerable error in interpolation has been estimated for each of the periods.
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  • 123
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    Pure and applied geophysics 122 (1984), S. 680-693 
    ISSN: 1420-9136
    Keywords: Physical seismic models ; Uniaxial loading ; Shear displacement ; Locked zone ; Seismoactivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Square plate models with a diagonally located slit in compression were studied photoelastically. The resulting stress field surrounding the discontinuity (slit) is evaluated before and after seismoactive (seismic-energy-releasing) shear displacement. The mechanism of the fast shear movement (stick-slip), including its radiation properties, in interpreted. The results confirm the existence of a central locked zone in the loaded slit, the limits of which coincide with the initiation points of stick-slip movements. The zone is interpreted as the source of the seismic energy release. The complementary measurements (direct optical and ultrasonic) are presented to verify the results of the photoelastic analysis. The results obtained are discussed in regard to the conclusions that follow from the theory of elasticity.
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  • 124
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    Pure and applied geophysics 122 (1984), S. 763-763 
    ISSN: 1420-9136
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  • 125
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    Pure and applied geophysics 122 (1984), S. 747-762 
    ISSN: 1420-9136
    Keywords: Total ozone ; Periodicities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Total ozone data series for 1957–82 at ten locations were subjected to Maximum Entropy Spectral Analysis. Besides the annual, semi-annual, and quasi-biennial oscillations, peaks were noticed at 3.5–4, 6–7, and 10–11 years. For Arosa, Switzerland, for a longer period (1932–71), an additional peak was indicated at about 16 years.
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  • 126
    ISSN: 1420-9136
    Keywords: precursory ground tilt ; temporal variation of crustal deformation ; the 1944 Tonankai earthquake ; leveling survey ; earthquake prediction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The temporal variation in precursory ground tilt prior to the 1944 Tonankai (Japan) earthquake, which is a great thrust-type earthquake along the Nankai Trough, is discussed using the analysis of data from repeated surveys along short-distance leveling routes.Sato (1970) pointed out that an anomalous tilt occurred one day before the earthquake at Kakegawa near the northern end of the focal region of the earthquake. From the analysis of additional leveling data, Sato's result is re-examined and the temporal change in the ground tilt is deduced for the period of about ten days beginning six days before the earthquake. A remarkable precursory tilt started two or three days before the earthquake. The direction of the precursory tilt was up towards the south (uplift on the southern Nankai Trough side), but the coseismic tilt was up towards the southeast, perpendicular to the strike of the main thrust fault of the Tonankai earthquake. The postseismic tilt was probably opposite of the coseismic tilt. The preseismic tilt is attributed to precursory slip on part of the main fault. If similar precursory deformation occurs before a future earthquake expected to occur in the adjacent Tokai region, the deformation may help predict the time of the Tokai earthquake.
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  • 127
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    Pure and applied geophysics 122 (1984), S. 781-792 
    ISSN: 1420-9136
    Keywords: Precursory tilt ; aseismic slip ; thrust faulting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract During three years preceding the 1976 Friuli earthquake, a continuous southward ground tilt was recorded by a tiltmeter placed near Tolmezzo, 15 km north-west of the epicentre of the impending earthquake. The cumulative ground tilt amounted to as much as 3 minutes of arc. Since the tiltmeter was placed in the proximity of an active fault, such a tilt can be explained if the fault slipped aseismically on its shallower section during the same three year period. Aseismic slip on the fault might have been caused by the same mechanism which concentrated stress in the region and eventually produced the 1976 earthquake.
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  • 128
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    Pure and applied geophysics 122 (1984), S. 793-811 
    ISSN: 1420-9136
    Keywords: Earthquake prediction ; Instability ; San Andreas fault
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The locked section of the San Andreas fault in southern California has experienced a number of large and great earthquakes in the past, and thus is expected to have more in the future. To estimate the location, time, and slip of the next few earthquakes, an earthquake instability model is formulated. The model is similar to one recently developed for moderate earthquakes on the San Andreas fault near Parkfield, California. In both models, unstable faulting (the earthquake analog) is caused by failure of all or part of a patch of brittle, strain-softening fault zone. In the present model the patch extends downward from the ground surface to about 12 km depth, and extends 500 km along strike from Parkfield to the Salton Sea. The variation of patch strength along strike is adjusted by trial until the computed sequence of instabilities matches the sequence of large and great earthquakes sincea.d. 1080 reported by Sieh and others. The last earthquake was theM=8.3 Ft. Tejon event in 1857. The resulting strength variation has five contiguous sections of alternately low and high strength. From north to south, the approximate locations of the sections are: (1) Parkfield to Bitterwater Valley, (2) Bitterwater Valley to Lake Hughes, (3) Lake Hughes to San Bernardino, (4) San Bernardino to Palm Springs, and (5) Palm Springs to the Salton Sea. Sections 1, 3, and 5 have strengths between 53 and 88 bars; sections 2 and 4 have strengths between 164 and 193 bars. Patch section ends and unstable rupture ends usually coincide, although one or more adjacent patch sections may fail unstably at once. The model predicts that the next sections of the fault to slip unstably will be 1, 3, and 5; the order and dates depend on the assumed length of an earthquake rupture in about 1700.
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  • 129
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    Pure and applied geophysics 118 (1980), S. 86-127 
    ISSN: 1420-9136
    Keywords: Stratosphere ; Aerosol layer ; Sulfates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract After briefly reviewing the observational data on the stratospheric sulfate aerosol layer, the chemical and physical processes that are likely to fix the properties of the layer are discussed. We present appropriate continuity equations for aerosol particles, and show how to solve the equations on a digital computer. Simulations of the unperturbed aerosol layer by various published models are discussed and the sensitivity of layer characteristics to variations in several aerosol model parameters is studied. We discuss model applications to anthropogenic pollution problems and demonstrate that moderate levels of aerospace activity (supersonic transport and space shuttle operations) will probably have only a negligible effect on global climate. Finally, we evaluate the possible climatic effect of a ten-fold increase in the atmospheric abundance of carbonyl sulfide.
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  • 130
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    Pure and applied geophysics 118 (1980), S. 3-19 
    ISSN: 1420-9136
    Keywords: Ultraviolet radiation ; Photodissociation ; Schumann-Runge bands ; Herzberg continuum ; Ozone bands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Solar radiation of λ〉175 nm and of Lyman-alpha at 121.6 nm is absorbed in the mesosphere and stratosphere by molecular oxygen (λ〈242 nm) and also by ozone molecules at λ〉200 nm. This paper describes the photodissociation processes resulting from absorption in the Schumann-Runge bands and Herzberg continuum of molecular oxygen and also in the Hartley, Huggins and Chappuis bands of ozone. Special consideration is given to differences between the stratospheric and mesospheric problems.
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  • 131
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    Pure and applied geophysics 118 (1980), S. 58-85 
    ISSN: 1420-9136
    Keywords: NO2 distribution ; Ozone destruction by NO x
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The catalytic destruction of stratospheric ozone by the oxides of nitrogen is believed to be an important part of the global ozone balance. The lack of sufficient measurements of NO x concentrations has impeded efforts to quantify this process. Recent measurements of stratospheric nitrogen dioxide from ground-based stations as well as aircraft and balloons have provided a first approximation to a global distribution of NO2 vertical columns at sunset. These observed vertical columns have been translated into time-dependent vertical NO2 profiles by means of a one-dimensional atmospheric photochemical model. Using recent observations of air temperature and ozone along with this information, the independent instantaneous (one second) rates of ozone production from oxygen photolysis P(O3), of ozone destruction from pure oxygen species (Chapman reactions) L(O x ), and of ozone destruction by nitrogen oxides L(NO x ) were estimated over the three-dimensional atmosphere. These quantities are displayed as zonal average contour maps, summed over various latitude zones, summed over various altitude bands, and integrated globally between 15 and 45 km. Although the global summation between 15 and 45 km by no means tells the complete story, these numbers are of some interest, and the relative values are: P(O3), 100; L(O x ), 15; L(NO x ), 45±15. It is to be emphasized that this relative NO x contribution to the integrated ozone balance is not a measure of the sensitivity of ozone to possible perturbations of stratospheric NO x ; recent model results must be examined for current estimates of this sensitivity.
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  • 132
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    Pure and applied geophysics 118 (1980), S. 128-151 
    ISSN: 1420-9136
    Keywords: Galactic cosmic rays ; Solar proton events ; Particle precipitation ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract An assessment is made of the relative contribution of certain classes of energetic particle precipitation to the chemical composition of the middle atmosphere with emphasis placed on the production of odd nitrogen and odd hydrogen species and their subsequent role in the catalytic removal of ozone. Galactic cosmic radiation is an important source of odd nitrogen in the lower stratosphere but since the peak energy deposition occurs below the region where catalytic removal of O3 is most effective, it is questionable whether this mechanism is important in the overall terrestrial ozone budget. The precipitation of energetic solar protons can periodically produce dramatic enhancement in upper stratospheric NO. The long residence time of NO in this region of the atmosphere, where catalytic interaction with O3 is also most effective, mandates that this mechanism be included in future modelling of the global distribution of O3. Throughout the mesosphere the precipitation of energetic electrons from the outer radiation belt (60°≲Λ≲70°) can sporadically act as a major local source of odd hydrogen and odd nitrogen leading to observable O3 depletion. Future satellite studies should be directed at simultaneously measuring the precipitation flux and the concomitant atmosphere modification, and these results should be employed to develop more sophisticated models of this important coupling.
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    Pure and applied geophysics 118 (1980), S. 177-188 
    ISSN: 1420-9136
    Keywords: Inertio-gravity waves ; Stokes drift ; Lagrangian-mean flow
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    Notes: Abstract Using standard ‘two-scaling’ techniques we calculate the Eulerian- and Lagrangianmean flows induced at second order in amplitude by small-amplitude, transient, non-dissipative, vertically-propagating inertio-gravity waves on anf-plane. The example is an idealized one, but illustrates a number of important features that are typical of wave, mean-flow interaction in a rotating, stratified fluid. Physical discussion of the solution is given in Section 4 of the review byMcIntyre (1980), which appears elsewhere in this issue.
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    Pure and applied geophysics 118 (1980), S. 35-57 
    ISSN: 1420-9136
    Keywords: Solar occultation technique ; Analysis of technique ; Inversion procedures
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    Topics: Geosciences , Physics
    Notes: Summary This article analyzes the nature of the aerosol information that current or planned spacecraft measurements could contribute toward the required input data for studies of natural anthropogenic influences on the middle atmosphere, and their consequent effects on our weather and climate. The analysis is conducted with particular reference to the solar occultation sounding technique as applied by the SAGE I experiment on the Atmospheric Explorer Mission B spacecraft. Its conclusions should prove to be of use in both the interpretation of the SAGE I data, and in the design of the follow-on mission on the Earth Radiation Budget satellite. Our analysis shows, in particular, that further studies are required in: the choice and number of sounding channels; the data taking sequence in relation to the atmospheric regions probed; the accuracy and vertical resolution of the atmospheric profiling, and their dependence on both the instrument/spacecraft parameters and the data inversion techniques; and the data reduction procedures. Neither of the selected channels is in a one-to-one relationship with an atmospheric constituent; hence, unless further assumptions are introduced, inversion techniques based on such a property are not applicable. The aerosol wavelengths are not satisfactory as they are only sensitive to the large size tail of the aerosol size distribution rather than to the predominant sizes; for these, UV wavelengths would be required. Owing to the change of the Sun's shape due to atmospheric refraction as the Sun either sets or rises, the higher altitudes will be scanned fewer times than the lower altitudes. Also, because transmission approaches rapidly unity above ∼40 km, the same high altitudes are more sensitive to measurement errors-errors that will propagate to lower altitude determinations when inverted profiles are reconstructed from the top of the atmosphere. These two factors, combined with the small air mass values at the high altitudes, are the cause of the mathematical ill-conditioning of the inversion problem. They point toward the need for a data-taking sequence strategy that would trade off between data storage and transmission constraints, larger accuracy at the high altitudes, and proper division of the atmosphere in order to overcome the ill-conditioning. Likewise, and as a result of the above considerations, there is a need for a detailed trade off study between data accuracy and vertical resolution of the reconstructed profiles. This should take into account the seasonal and geographical variations in the distribution of atmospheric constituents, as well as a representative statistical set at any given location and time, appropriate error measures and their vertical profiles, and several inversions utilizing as initial guesses profiles that depart from the true ones. It is also shown that the aerosol and ozone number densities cannot be recovered simultaneously without introducing some formula for the aerosol extincition or assumptions on the form of the aerosol size distribution. This problem is not resolved by the addition of sounding channels because each such channel introduces an additional unknown aerosol extinction. Thus, one is led to a separate rather than a simultaneous determination of the various constituents by resorting to complementary measurements. For a future experiment, it is suggested to determine the ozone separately from measurements at a close pair of appropriate wavelengths between which the aerosol extinction varies slowly whereas that of ozone exhibits a rapid variation. A similar technique could also be used for the separate determination of NO2. The relaxation-type of inversion suggest byChu andMcCormick (1979) does not seem to be appropriate because each channel is not sensitive selectively to an individual constituent, the aerosol channels are not sensitive to the important sizes in the distribution, and the sensitivity of the channels to the constituents of interest varies greatly with altitude. In the retrieval of the vertical profiles, the cause of the ill-conditioning of the inversion is identified. Two approaches are suggested for overconing this problem: (i) build the profile starting from the top of the atmosphere (forward procedure) but with an initial layer of sufficient air mass, or preferably (ii) reconstruct the profile from the lowest altitude reached (backward procedure) with a renormalization at the top of the atmosphere. In this process, the minimization search method (Fymat, 1976) would appear to be a better technique than the onion-peeling technique, as demonstrated byMill andDrayson (1978). In order to maximize the scientific return of SAGE I, a data inversion procedure is proposed. It assumes that (i) there are no aerosols above ∼25 km, and no NO2 below this altitude (as suggested byChu andMcCormick, 1979), (ii) below ∼25 km, ozone (and NO2, if present) could be determined separately, and (iii) the aerosol has a known refractive index at all wavelengths of interest, is assumed to be spherical (or describable in terms of ‘equivalent spheres’), and the minimum and maximum radii of its size distribution are known a priori. Under these assumptions, it is possible to retrieve the neutral density, NO2 and O3 profiles above ∼25 km, by either the forward or the backward procedure described above. Taking into consideration the power law variation of the air density with altitude, it is further possible to reconstruct the corresponding profiles at all the lower altitudes from the determinations in the altitude range ∼30–40 km. Below ∼25 km, the four SAGE I channels would then all become available for the aerosol inversion. While the profile reconstruction could proceed as for the higher altitudes, the aerosol inversion at each individual altitude presents problems of its own. Results of numerical experiments for aerosol inversion using all four SAGE wavelengths and seven different inversion routines are presented. If good a priori information is available on the sought size distribution solution, reasonably satisfactory inversions can be performed (see line 1 of Table 2, and Fig. 3c and 3d). However, in the absence of such information, there are as many solutions as inversion methods tried, in complete conformity with the well-known ill-conditioning of the problem. Among methods providing physically meaningful solutions, no method could be singled out as preferable to the others. In these inversions, the data were assumed to be exact, and 99% of the distribution were used. Under different conditions, the nonuniqueness of the inversion would be further compounded. Lastly, based on the present study, a strategy is suggested for the design and data interpretation of a follow-on SAGE-type experiment. Considering the important advantages to this problem presented by forward scattering, as demonstrated byFymat andMease (1978), a composite (extinction-forward scattering) experiment is recommended for the future experiments.
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    Pure and applied geophysics 118 (1980), S. 775-782 
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    Keywords: Aerosol extinction ; Solar radiation ; Tropical meteorology
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    Notes: Abstract Solar radiance measurements covering over seventeen months are analysed for a location beside the Lagos Lagoon. The aerosol extinction coefficient was generally higher in the dusty months than in the wet months. ‘Clean air’ estimates of the coefficient are made. Data on its wavelength dependence are also presented.
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    Pure and applied geophysics 118 (1980), S. 823-830 
    ISSN: 1420-9136
    Keywords: Rayleigh wave dispersion in Apulia ; Upper mantle structure of Apulia ; Apulia, upper mantle structure
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    Notes: Abstract Phase velocities of Rayleigh waves for the Adriatic Sea area are obtained in the period range 25–190 sec along the path (l'Aquila-Trieste) AQU-TRI and 20–167 sec along the path (Trieste-Bari) TRI-BAI. The phase velocities are systematically higher than the known values for the surrounding regions. The data inversion indicates the presence of a lithosphere typical of stable continental areas with clear high-velocity lid (V s ∼4.6 km/sec) overlying a well developed low velocity zone (V s ∼4.2 km/sec).
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    Pure and applied geophysics 119 (1980), S. 841-853 
    ISSN: 1420-9136
    Keywords: Resistivity ; inversion techniques
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    Notes: Abstract Model uncertainty is introduced into direct-current resistivity data by adding random changes to layer thicknesses in a ten-layer model. The resulting information is then aliased by generating a sounding curve which contains less information than the ten resistivities and nine thicknesses. These sounding curves are then inverted via the Backus-Gilbert algorithm using singular value decomposition to obtain solutions in terms of simpler two-or three-layer models. Quantitative results confirm what has been known qualitatively for many years as the principle of equivalence. An interesting result is that the geometric average of a given suite of noisy models is virtually identical to the best-fit model for the average of the noisy curves. The results show that the inversion of resistivity data by nonlinear least-squares parameter fitting is stable in the sense that noise in the data inverts to the same magnitude of noise in the model.
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    Pure and applied geophysics 118 (1980), S. 355-377 
    ISSN: 1420-9136
    Keywords: Ozone depletion ; Chlorofluorocarbons
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    Topics: Geosciences , Physics
    Notes: Abstract Results are presented from a two-dimensional, time-dependent model of the atmosphere which has been used to investigate perturbations to the ozone layer due to chlorofluorocarbons. The unperturbed stratosphere is modelled well with the observed features of the ozone distribution reproduced. The main features of the perturbation calculations are the large latitudinal and seasonal variations found in the modelled ozone reductions with greates reductions where the total ozone amounts are largest. The importance of at least a two-dimensional study in problems of this kind is stressed and the important role of dynamical and radiative processes, as well as chemical, is indicated.
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    Pure and applied geophysics 120 (1982), S. 67-78 
    ISSN: 1420-9136
    Keywords: Monsoon ; Transport ; Tropical meteorology ; Water vapour
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    Notes: Abstract The advective monthly mean transfer of water vapour in the layer below 700 mbar is investigated for India for the years 1962 to 1972 and for the months January to September. The average zonal and meridional components of the transfer of water vapour for India are obtained. They are further averaged for different combinations of the pre-monsoon months from January to May and are correlated with the summer monsoon rainfall. The correlation coefficients for zonal transfer of water vapour are either negative or small positive for different combinations of the months mentioned above. The correlation coefficients for the meridional transfer of water vapour are positive. The maximum value is 0.74 for the March to May combination and is statistically significant at the 1% level. An extensive investigation is, therefore, made for the March to May averages of water vapour transfer for four broad regions of India. The parameters of water vapour transfer for these regions are compared with the threshold values and the prediction category, normal or drought, for the subsequent summer monsoon season is determined for all years. The correlation coefficient between the index of drought, as determined from parameters of water vapour transport and rainfall departure, is statistically significant at the 2% level.
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    Pure and applied geophysics 120 (1982), S. 123-135 
    ISSN: 1420-9136
    Keywords: Tropical meteorology ; Atmospheric electricity
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    Topics: Geosciences , Physics
    Notes: Abstract The results of atmospheric electric measurements over a twenty year period (1961–1980) are reviewed for Ibadan situated in the tropical rain forest of Nigeria. The aim is to present the data in an easily accessible form.
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    Pure and applied geophysics 120 (1982), S. 197-201 
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    Pure and applied geophysics 119 (1981), S. 901-912 
    ISSN: 1420-9136
    Keywords: Monsoon depression ; Cyclogenesis ; Barotropic instability
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    Notes: Abstract The role of barotropic processes in the development of a monsoon depression, formed on 5 July 1979 during MONEX observational period, is studied by considering it as a quasi-geostrophic divergent barotropic instability problem of zonal flow of 3 July 1979 at 700 mb level. Numerical solutions are obtained by initial value approach. The preferred wave has a wavelength of 2750 km, an e-folding time of 4.3 days, a period of 6.5 days and an eastward phase speed of 4.9 ms−1. Structure of preferred wave is found to be in good agreement with the observed horizontal structure of the depression at 700 mb. Poleward momentum transports are found to predominate over equatorward transports.
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    Pure and applied geophysics 119 (1981), S. 922-933 
    ISSN: 1420-9136
    Keywords: Extreme precipitation ; Tropical meteorology
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    Notes: Abstract The greatest one-day rain amounts recorded at individual stations in the country during the last 41-year period from 1940 onwards were examined for all observatories as well as State rain-gauge stations in an attempt to bring out up-to-date information on the greatest recorded point rainfall for the duration of one day. Outstanding one-day point rainfall amounts recorded prior to 1940 were also examined and have been included in this note along with their date and year of occurrence by way of comparison. A generalized chart has been prepared based on the percentage ratios of the greatest one-day rainfall to the mean annual rainfall of about 300 observatory stations distributed uniformly over the entire country. On the basis of Depth-Area-Duration (DAD) analyses of the most severe rainstorms which occurred over different plain areas of the country, it has been found that the 2 July, 1941, rainstorm gave the highest areal rain depths in the country for different areas. Comparison with similar areal rain depths of the tropical USA has shown that rain depths of the July, 1941, rainstorm were higher for all areas excepting the areas of 500 sq. miles (1295 sq. km) and 1000 sq. miles (2590 sq. km).
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    Pure and applied geophysics 119 (1981), S. 990-997 
    ISSN: 1420-9136
    Keywords: Atmospheric trace gases ; Atmospheric chemistry ; Chemical composition of atmospheric boundary layer
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    Notes: Abstract Weekly air samples were collected at Cape Kumakahi (0 km) and at nearby Mauna Loa Observatory (3.4 km) which is above the boundary layer. EC/GC and GC/FID techniques were used to measure CH3I, CHCl3, CO and CH4, which are largely natural in origin, and C2Cl4, CCl4, CH3, CCl3, CCl3F (F-11), CCl2F2 (F-12), CHClF2 (F-22) and C2F3Cl3 (F-113), which are due to anthropogenic activities. It was found that all these gases are significantly (α≤0.05) more abundant in the boundary layer than above it.
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    Pure and applied geophysics 119 (1981), S. 1003-1023 
    ISSN: 1420-9136
    Keywords: Geoelectric data ; Transmission Line analogy ; Filter theory ; stable stochastic inverse
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    Topics: Geosciences , Physics
    Notes: Abstract A simple numerical inversion scheme for estimatingn-layer model parameters from observed geoelectrical resistivity data can be used in either the space or wavenumber domain. The technique utilizes Madden's Transmission Line Analogy to compute the resistivity transforms and linear filter theory to accomplish the excursions between the space and wavenumber domains. The inversion is effected by an iterative refinement scheme employing the stochastic inverse which is approximate to the generalized inverse. No singular decomposition analysis is required and the scheme is stable under ill conditions. The inversion scheme not only gives the desired estimates; it exposes redundant parameters and irrelevant data and is easily programmed on a desk-top mini computer. Examples of inverse modeling with hypothetical and field data are discussed.
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    Notes: Abstract P- and S-wave velocity distributions obtained from DSS measurement have been used as a constraint in the inversion of surface-wave dispersion data. The combined interpretation was made as an attempt to enhance the resulting velocity models and to test the possibility to draw conclusions about the density distribution. The result indicates a potential value of a combined interpretation but it is obvious that very accurate velocity distributions are needed. The achieved density distribution is in good agreement with reported densities derived from gravimetric studies.
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    Pure and applied geophysics 119 (1981), S. 1093-1099 
    ISSN: 1420-9136
    Keywords: Baltic Shield ; Deep seismic sounding ; Earthquakes in Finland
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    Topics: Geosciences , Physics
    Notes: Abstract The lithospheric models obtained for the Baltic Shield by using deep seismic soundings are discussed and results from different parts of the shield are compared with models achieved by the investigation of surface waves and of P to S converted waves. The results are found to agree rather well with each other particularly with regard to the first interface (at a depth of 10–15 km) and the whole thickness of the crust (c. 40 km). The macroseismic focal depth determinations of regional earthquakes are correlated with lithospheric structure. The main maximum in the focal depth distributions of Finnish earthquakes occur at a depth of 10–12 km. The geographical distribution of the earthquake epicentres suggests several seismo-active zones in the northern Baltic Shield. One new finding in this field concerns the Lapland zone, which runs in a north-westerly direction.
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    Pure and applied geophysics 119 (1981), S. 1116-1124 
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    Notes: Abstract A long-range Scandinavian seismic profile of August 1979 is subjected to a preliminary evaluation by means of the records of the permanent Swedish network of stations. The resulting travel times confirm those earlier adopted in the calculation of Swedish earthquakes for the period 1951–1976.
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    Pure and applied geophysics 119 (1981), S. 1107-1115 
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    Notes: Abstract The deep seismic sounding project ‘Blue Norma’ was carried out in the summer of 1977 in northern Scandinavia in order to investigate the deep structure of the Norwegian continental margin and the Caledonian mountain chain. During the measurements, by chance the core phase PKIKP of an earthquake at the New Hebrides was recorded with 30 seismic field stations along a profile through the central Caledonides. The results of the refraction seismic data, as obtained by a ray-tracing method, are presented and compared to the interpretation of the relative residuals of the PKIKP travel times. From both data sets a continentward down-dipping crust-mantle boundary is evaluated. From the interpretation of the refraction seismic measurements a crustal thickness of 32 km below the coastline and 42 km below the central mountain chain is obtained. The increase of the crustal thickness derived by the inversion of the travel-time residuals along this line amounts only to 6 km. This considerable discrepancy can only be explained by an eastward increasing seismic velocity in the mantle.
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    Keywords: Carpathians ; Three-dimensional seismic modelling
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    Notes: Abstract The joint analysis performed for the Carpathian region from seismological data (three-dimensional fields of velocities, areas of concentration of earthquake foci in the Vrancea focal zone) and interpretation of DSS data and those of other geophysical fields have permitted to obtain new evidence for the earth's crust and mantle structure in this region.
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    Pure and applied geophysics 119 (1981), S. 1192-1196 
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    Pure and applied geophysics 119 (1981), S. 1197-1197 
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    Pure and applied geophysics 118 (1980), S. 913-934 
    ISSN: 1420-9136
    Keywords: Thermal ; Convection ; Cloud modelling
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    Notes: Abstract For a thermal starting from rest, the scales of motion consistent with the initial conditions are given. An alternative time scale based on the motion of the thermal is derived. The anticipated similarity solutions for thermals are summarised and possible qualitative differences between solutions are given. Within this consistent framework previously published laboratory and numerical models of thermals are discussed. Reasons why numerical models have not rigorously demonstrated the existence of a self-similarity solution are considered. Comparisons of all available results show that a single similarity solution valid for all thermals does not exist.
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    Pure and applied geophysics 118 (1980), S. 953-963 
    ISSN: 1420-9136
    Keywords: Electric field ; Atmospheric electric field ; —seasonal variation of
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    Notes: Abstract The measurement of the atmospheric electric field was carried out with a field mill at a small island in a bay on the Pacific coast of Japan. The data obtained during 80 months from 1971 to 1977 were analysed. It was found that characteristically the diurnal variation regularly alters with the seasons. Whereas the electric field in winter has the same diurnal pattern as that observed at globally representative stations, it exhibits in summer a pattern depending on the variation of the local electric conductivity. The alteration is inferred to be associated with regional atmospheric conditions surrounding the observation site.
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    Pure and applied geophysics 118 (1980), S. 935-952 
    ISSN: 1420-9136
    Keywords: Cloud microstructure ; Clouds-liquid water content in
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    Notes: Abstract This paper examines the evidence for the model of a small cumulus cloud represented as a quasi static but turbulent entity, growing on the upshear side and decaying on the downshear side. While the air just outside the cloudy outline is, on average, stationary relative to the embedding airmass, there is a slight flow, upwards and forward as though the updraft has induced upward motion in the clear air outside the cloud, on the growing side. On the decaying side the motion is downwards and away from the cloud. This is a flow pattern which is not consistent with the air flowing around the cloud as it moves forward but it agrees well with the picture given. Decayed remnants of cloud are found throughout the air previously occupied by the cloud. The cloud outline moves through the embedding air at a velocity which is almost as large as the relative motion of the subcloud feeding airflow (which is almost free from internal wind shear in strong convection). The mixing of dry air from above the inversion yields the observed diluted liquid water content in small cumuli, if such mixing is allowed to proceed until the cloud density equals that of the surrounding air. Quantitative conditions relating the liquid water to inversion temperature and moisture changes, and to the stability of the environment are presented. The strong vertical mixing from the top of the cloud downwards is important to microphysical processes.
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    Pure and applied geophysics 118 (1980), S. 880-912 
    ISSN: 1420-9136
    Keywords: Numerische Wetterprognose ; Rossby-und Lärmwellen ; Lärmhypothese ; Initialisierung ; Lärmfilterung ; Numerical weather prediction ; Rossby-and noise waves ; noise hypothesis ; initialization ; noise filtering
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    Topics: Geosciences , Physics
    Description / Table of Contents: Summary The process of initialization of the atmospheric field variables and the very short computing time steps are key problems in numerical large-scale weather simulation based on stringent fluid-dynamic models. In the present paper it is discussed how these two prediction problems cantogether be removed with the aid of special compatibility conditions (diagnostic differential equations) between the atmospheric field parameters. These equations can be utilized simultaneously (1) to mutually adjust the initial fields of the meteorological variables so that noise effects are suppressed as far as possible (unfiltered systems) (2) to substitute original flow equations so that the short-periodic, meteorologically irrelevant noise waves (requiring short time steps) in the mathematical solutions are eliminated (filtered systems). The consistent usage of noise filtering relationship results (with a reasonable amount of mathematical effort) in noise-wave components being considerably reduced and meteorologically relevant Rossby-waves being largely maintained during the numerical integration process. The practicability of the noise-filtering theory is analytically discussed on the basis of a (barotropic) one-layer prediction model. The problems of initialization and noise-filtering (time step) are discussed separately.
    Notes: Zusammenfassung Die Anfangsadjustierung der atmosphärischen Zustandsvariablen und die sehr kleinen Rechenzeitschritte sind Kernprobleme der numerischen Simulation von grossräumigen Wetterentwicklungen auf der Basis strenger hydrodynamischer Vorhersagemodelle. In dem vorliegenden Aufsatz wird ausführlich diskutiert wie beide Prognosehindernisse mit geeigneten Verträglichkeitsbedingungen (diagnostische Differentialgleichungen) zwischen den atmosphärischen Feldgrössengemeinsam beseitigt werden. Diese Bedingungsgleichungen sind gleichzeitig verwendbar, um (1) die Anfangsfelder der meteorologischen Variablen so aneinander anzupassen, dass kurzperiodische Lärmeffekte weitgehend unterdrückt werden (ungefilterte Systeme) (2) originäre Modellgleichungen zu ersetzen, so dass die meteorologisch irrelevanten Lärmwellen (mit lästig kleinen Zeitschritten) in den mathematischen Lösungen eliminiert werden (gefilterte Systeme). Die konsequente Nutzung der Lärmfiltertechnik führt (bei einem vertretbaren mathematischen Aufwand) in der Praxis dazu, dass während des numerischen Lösungsprozesses Lärmwellenanteile bis zur Unwirksamkeit reduziert und meteorologisch relevante Rossby-Wellen hinreichend gut konserviert werden. Die Praktizierbarkeit der Lärmfiltertheorie wird an einem (barotropen) 1-Schichtenprognosemodell rechnerisch realisiert und veranschaulicht. Die Kernprobleme der Initialisierung und der Lärmfilterung (Zeitschritt) werden dabei separat diskutiert.
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    Pure and applied geophysics 118 (1980), S. 964-974 
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    Keywords: Atmospheric chemistry ; Interhemispheric differences ; Mercury
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    Notes: Abstract Atmospheric mercury concentrations were measured during a nautical expedition on the Atlantic Ocean between Hamburg (54°N, 10°E) and Santo Domingo (20°N, 67°W). In addition, samples were taken during flights on a commerical aircraft in the upper and middle troposphere between 60°N and 55°S, mostly over the Pacific Ocean. The data obtained in the lower troposphere over the Northern Atlantic show considerable variation in the Hg concentrations, with values ranging between 1 and 11 ng/m3; the average concentration was found to be 2.8 ng/m3. The upper tropospheric data show an interhemispheric difference with average values of 1.45 ng/m3 and 1.08 ng/m3 in the Northern and Southern Hemisphere, respectively. This suggests that mercury production occurs predominantly over the continents both by natural and anthropogenic processes. The mercury content in aerosols was found to be ≤0.3 ng/m3, or one-tenth of the atmospheric concentration. The data indicate a mean residence time of mercury in the atmosphere of a few months to one year.
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  • 158
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    Pure and applied geophysics 118 (1980), S. 975-989 
    ISSN: 1420-9136
    Keywords: Rock mechanics ; Dilatancy-diffusion, Velocity changes
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    Topics: Geosciences , Physics
    Notes: Abstract Compressional and shear-wave velocities (V p andV s ) were measured during the generalized triaxial deformation (i.e.σ 1≠σ 2=2σ 3) of pyrophyllite. Observed velocity changes could be ascribed to crack development during dilatancy. Velocity changes were very localized with respect to the ultimate failure plane. The orientation and development of the failure plane was continuously observed with laser holography. Velocity reverals, i.e. changes from a decreasing trend to an increasing trend, were documented in a wet sample in bothV p andV s . These changes in bothV p andV p are inconsistent with dialatancy-diffusion models. The reversals were interpreted as a reflection of local stress reorientation caused by a slowly propagating fault.
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  • 159
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    Pure and applied geophysics 118 (1980), S. 1007-1014 
    ISSN: 1420-9136
    Keywords: Eddy diffusivity ; Stratosphere ; Lower mesosphere
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    Topics: Geosciences , Physics
    Notes: Abstract Meteorological rocket soundings, launched between 1968–74 at six locations representative of low, middle, and high latitudes in the northern hemisphere, are employed to determine the vertical, meridional and off-diagonal components of the eddy diffusivity in the northern hemispheric statosphere and lower mesosphere. It is shown that the distribution of the vertical and meridional components of the eddy diffusivity are similar in the northern hemisphere, although the magnitude of the former is 107 smaller than that of the latter; the magnitude of the off-diagonal eddy diffusivity is about 103 smaller than that of the meridional eddy diffusivity. In the troposphere, a maximum eddy diffusivity occurs in the mid-latitude at about 7 km above the mean sea level for both the summer and winter seasons. In the stratosphere, a maximum eddy diffusivity occurs in the mid-latitude at about 33 km in the winter, but no maximum in the summer.
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    Pure and applied geophysics 118 (1980), S. 1015-1032 
    ISSN: 1420-9136
    Keywords: Eddy diffusion coefficients ; Atmosphere 30–60 km
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    Topics: Geosciences , Physics
    Notes: Abstract The results of numerical models or of new observational programs are checked by comparing them with past observations. Also, it is desirable that the eddy diffusion coefficients used in two-dimensional models be derived from the same data set as the circulation statistics which the model outputs are checked against, so that all results refer to the same atmospheric conditions. For the first time, the three components of the eddy diffusion matrix, from 30–60 km, 80°N–10°S are computed, together with the means, variances and covariances of the wind and temperature through the same region using the same data set for 1960–76 and the same handling and analysis methods for all variables. Horizontal diffusivities,K yy , are obtained from the variance and integral time scale of the meridional wind speed. The present values are generally smaller than past estimates, presumably because temporal variations longer than a month have been removed in this work. Estimates ofK yz are based on the tentative assumption that the diffusivity is proportional to the slope of isentropic surfaces, and estimates ofK zz are based on the assumption that small-scale gravity waves are primarily responsible for vertical mixing.
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  • 161
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    Pure and applied geophysics 118 (1980), S. 1033-1051 
    ISSN: 1420-9136
    Keywords: Multiple scattering ; Ozone photochemistry ; Trace substances ; Two-dimensional model
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    Topics: Geosciences , Physics
    Notes: Abstract Computations of concentrations of minor stratospheric gases using a two-dimensional model of the stratosphere are reported. The model includes Rayleigh scattering. This results in an increase in the photodissociation rate computation time by a factor of 1.5. The effect of ground albedo is assessed by comparing our results with a calculation of photolysis rates for a constant albedo with latitude. Comparison of results with a reference model including only molecular absorption are also made. The largest differences (≲50%) occur in NO and OH. An approximate expression for including the effects of Rayleigh scattering and surface reflectance in multi-dimensional models is suggested.
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  • 162
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    Pure and applied geophysics 118 (1980), S. 1052-1065 
    ISSN: 1420-9136
    Keywords: Microwaves ; Ozone ; Passive sounding
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    Topics: Geosciences , Physics
    Notes: Abstract It is shown how to retrieve the atmospheric ozone profile by means of ground based microwave measurements of the radiative intensity. Chahine's iteration method is used. The method is tested by a numerical experiment. The retrieval rms about the mean error is approximately 0.4 ppm. The required measurement accuracy for the brightness temperatures is ±0.01 K.
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  • 163
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    Pure and applied geophysics 118 (1980), S. 1076-1089 
    ISSN: 1420-9136
    Keywords: Precipitable water
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    Topics: Geosciences , Physics
    Notes: Abstract Values for mean precipitable water are computed for four seasons of the year and for different regions of the Southern Hemisphere. Relationships between surface dew-point temperature and precipitable water were studied for these regions. A harmonic analysis of our data on precipitable water is attempted. Out results are presented and discussed.
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  • 164
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    Pure and applied geophysics 118 (1980), S. 1066-1075 
    ISSN: 1420-9136
    Keywords: Intertropical convergence zone ; Onset of monsoon ; Indian summer monsoon
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    Topics: Geosciences , Physics
    Notes: Abstract The paper defines the intertropical convergence zone. (ITCZ) in the Indian monsoon region during the northern summer, identifies it with the northern boundary of the advancing monsoon and suggests that its seasonal movement can serve as an indicator of onset, advance and withdrawal of the monsoon. Evidence suggesting the movement of the ITCZ which is associated with the equatorial trough of low pressure is indirectly furnished by an analysis of the isallobaric or height-tendency field which reveals a distinct gradient towards the north/south during period of advance/withdrawal of the monsoon. A comparative study of the dates of onset of monsoon during two successive years appears to suggest that some of the problems encountered in using rainfall as the sole criterion for determining the onset and advance of the monsoon may be over-come by using the ITCZ concept as proposed in the present paper. Attention is drawn to the effects of synoptic-scale disturbances on the normal dates of onset, advance and withdrawal of the monsoon.
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    Pure and applied geophysics 118 (1980), S. 1090-1108 
    ISSN: 1420-9136
    Keywords: Atmospheric aerosols ; Ice crystals ; Scavenging
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    Topics: Geosciences , Physics
    Notes: Abstract A theoretical model is presented which allows computing the efficiency with which aerosol particles of 0.001 ≤r≤1 μm are collected by columnar ice crystals in air of various relative humidities, temperatures, and pressures. Particle capture due to Brownian diffusion, thermo- and diffusiophoresis is considered. It is shown that phoretic effects importantly determine the particle capture process of 0.01≤r≤1 μm. The various pressure-temperature levels studied are found to affect the collection efficiency only ifr〉0.1 μm. Comparison shows that water drops generally are better aerosol particle scavengers than columnar ice crystals.
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  • 166
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    Keywords: Atmospheric aerosols ; Ice crystals ; Scavenging
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    Notes: Abstract A theoretical model is presented which allows computing the efficiency with which aerosol particles of radius 0.1≤r≤10 μm are collected by simple ice crystal plates of radius 50≤a c ≤640 μm in air of various relative humidities, temperatures and pressures. Particle capture due to thermophoresis, diffusiophoresis and inertial impaction are considered. It is shown that the capture efficiency of an ice crystal in considerably affected by phoretic effects in the range 0.1≤r≤1 μm. For aerosol particles ofr〉1 μm the efficiency is strongly controlled by the flow field around the crystal and the density of the aerosol material. Trajectory analysis also predicts that aerosol particles are preferentially captured by the ice crystal rim. Our theoretica results are found to agree satisfactorily with the laboratory studies presently available. Comparison shows that for the same pressure, temperature and relative humidity of the ambient air ice crystal plates are better aerosol particle scavengers than water drops.
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    Pure and applied geophysics 118 (1980), S. 1145-1154 
    ISSN: 1420-9136
    Keywords: Atmospheric chemistry ; Nitrogen compounds ; Ocean source
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    Topics: Geosciences , Physics
    Notes: Abstract The paper deals with the atmospheric gaseous nitrogen-compounds under special consideration of the ocean being a source for NH3. The distribution of NH3 and NH4 + in the ocean is discussed. Additionally a survey of measured marine pH-values is given. While in temperate latitudes the source-strength of the ocean seems to be low, no such statement can be made at present for tropical latitudes owing to lack of measurements.
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    Pure and applied geophysics 118 (1980), S. 1155-1169 
    ISSN: 1420-9136
    Keywords: Magnetic anomalies ; Spheres ; Wavenumber domain ; Noise
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    Topics: Geosciences , Physics
    Notes: Abstract A Fourier transformation of the magnetic field from a magnetized sphere allows a particularly simple interpretation of the parameters of the sphere. The depth to the centre and total magnetic moments of the sphere are related to the intercept and slope of the power spectrum. The horizontal centre and direction of magnetization are related to slope and intercept of the phase spectra in two perpendicular, horizontal directions. Examples with artificial data contaminated by various noise components are presented.
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    Pure and applied geophysics 118 (1980), S. 1130-1144 
    ISSN: 1420-9136
    Keywords: Antarctic precipitation ; Heavy metal concentrations
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    Topics: Geosciences , Physics
    Notes: Abstract Ion exchange and flameless atomic absorption spectrophotometry methods were used to measure the concentrations of sodium, manganese, iron and silver in snow accumulating at several sites on the Antarctic continent. The results show that the ratio of Mn/Fe is consistently close to the crustal value at all sites. The silver concentrations observed suggest a different origin, probably oceanic. When referenced to sodium, the degrees of enrichment of silver, manganese and iron increase by factors of 8, 2 and 2 respectively over a distance of 500 km from the ocean, after changes in sodium are accounted for. Investigation of the heavy metal content of fresh falling precipitation occorring on the Ross Ice Shelf, has shown that more enhanced enrichments of silver, manganese and iron occur in this fresh precipitation by factors up to 100, than in samples of snow and firn collected from shallow (up to 2 meters depth) pits at the same locations. Because the occurrences of these precipitation types vary temporally and geographically, it seems apparent that the shear stress conditions in the near surface boundary layer need to be considered in studies of snow and ice chemistry, particularly in polar regions where the chemical composition of permanent snow and ice fields are often investigated for evidence of climatic change, of glaciological behavior and of origins of chemical constituents.
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    Pure and applied geophysics 118 (1980), S. 1170-1178 
    ISSN: 1420-9136
    Keywords: Seismology ; Love waves ; Laterally nonhomogeneous layer
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    Topics: Geosciences , Physics
    Notes: Abstract Rayleigh's principle and the concept of the local wave number have been utilised for the approximate determination of the dispersion of Love waves propagating in a laterally heterogeneous layer lying over a homogeneous half-space. The shear wave velocity and the rigidity in the surface layer have been assumed to decrease with the increase of the lateral distance from the origin. The range of validity of the dispersion equation obtained by this method has been examined critically. It was found that: (a) for existence of Love waves the minimum value of shear wave velocity in the layer must be less than that in the matter below, and (b) the phase velocity of Love waves decreases with the increase of the lateral distance from the origin.
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    Pure and applied geophysics 118 (1980), S. 1191-1191 
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    Pure and applied geophysics 118 (1980), S. 1179-1190 
    ISSN: 1420-9136
    Keywords: Time-term method ; Crustal structure from earthquakes ; Seismic refraction experiment ; California
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    Notes: Abstract TheP-arrival times of local and regional earthquakes that are outside of a small network of seismometers can be used to interpret crustal parameters beneath the network by employing the time-term technique. Even when the estimate of the refractor velocity is poorly determined, useful estimates of the station time-terms can be made. The method is applied to a 20 km diameter network of eight seismic stations which was operated near Castaic, California, during the winter of 1972–73. The stations were located in sedimentary basins. Beneath the network, the sedimentary rocks of the basins are known to range from 1 to more than 4 km in thickness. Relative time-terms are estimated fromP-waves assumed to be propagated by a refractor in the mid-crust, and again fromP-waves propagated by a refractor in the upper basement. For the range of velocities reported by others, the two sets of time-terms are very similar. They suggest that both refractors dip to the southwest, and the geology also indicates that the basement dips in this direction. In addition, theP-wave velocity estimated for the refractor of mid-crustal depths, roughly 6.7 km/sec, agrees with values reported by others. Thus, even in this region of complicated geologic structure, the method appears to give realistic results.
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    Pure and applied geophysics 118 (1980), S. 1192-1208 
    ISSN: 1420-9136
    Keywords: Free oscillations ; Earth ; Source moment tensor ; Multiplet splitting
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    Topics: Geosciences , Physics
    Notes: Abstract It is shown, through numerical experiments, that the effect of ignoring ellipticity and rotation of the earth when inverting free oscillation data in moment tensor studies, is to introduce spurious spectral components in the solution. For numerical simulation of the data conditions of the 1970 deep Colombian event the spurious part has isotropic and deviatoric components, besides a distortion in the phase spectra which may lead to artificial precursive source in the solution. The magnitude of the artificial isotropic component is of the order of 10% of the real source moment tensor, depending on the data set used in the inversion. Measuring the excitation of each mode at each station using the technique of integrating over the spectral peaks does not cancel completely the effect of multiplet splitting, in particular that splitting due to rotation of the earth. The effect of lateral heterogeneities was simulated by introducing arbitrary splitting parameters which produced scattering in the eigenperiods compatible with those observed. For that splitting the inversion rendered additional isotropic components. We conclude that the observed implosive precursor the the 1970 Colombian event could have been artificially introduced by ignoring rotation, ellipticity and lateral heterogeneities of the earth. A procedure to invert free oscillation data for an elliptical rotating earth is proposed. It could be applied to a laterally inhomogeneous earth if the excitation for that model could be computed. Its application to real data for the deep Colombian event indicates that we will need to improve our knowledge on the effect of rotation, ellipticity, lateral heterogeneities and anelasticity on free oscillation and their excitation in order to solve accurately for the six components of the moment tensor independently.
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    Pure and applied geophysics 118 (1980), S. 1214-1227 
    ISSN: 1420-9136
    Keywords: Polar phase shift ; Rayleigh wave propagation
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    Topics: Geosciences , Physics
    Notes: Abstract The precision of measurement of surface-wave phase velocities at very long periods has reached a point where the exact, rather than asymptotic, form of the spherical harmonics must be considered in order to compute theoretical phase velocities or phase delays. The zeroth-order (i.e. constant) polar phase shift afterBrune et al. (1961) applies only between stations antipodal to each other. Everywhere else a correction for incomplete polar phase shift must be applied even if the waves do not cross a pole between the stations. The correction can exceed one percent of the total phase delay and thus be of the same order as the expected regional anomalies. It depends on the epicentral distance on the signal period and on the focal mechanism; the latter dependence can make the practical application cumbersome. We derive first-order asymptotic formulae for the correction of local phase velocities and total phase travel times of Rayleigh waves.
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    Pure and applied geophysics 118 (1980), S. 1209-1213 
    ISSN: 1420-9136
    Keywords: Seismology ; Phase velocity dispersion ; Rayleigh waves ; ‘Hedgehog’ inversion method ; Lithosphere-asthenosphere system in Europe
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    Notes: Abstract Long-period recordings of dispersive Rayleigh waves along numerous station lines, or ‘profiles’, in Europe have for the first time permitted a uniform inversion of these observations based on a new method of phase velocity regionalization. Regional dispersion relations obtained by this method have then been subjected to a complete inversion procedure commonly known as the ‘hedgehog’ method. The results are presented in a map outlining the thickness of the lower lithosphere (‘lid’) and the shear (S) velocities in both the ‘lid’ and the asthenosphere ‘channel’. A comparison of these results with the minimum compressional (P) wave velocities in the asthenosphere and their corresponding depths provides an estimate of theV p /V s ratio for the asthenosphere in the European area.
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    Pure and applied geophysics 118 (1980), S. 1232-1233 
    ISSN: 1420-9136
    Keywords: Theoretical seismograms ; Reflectivity method ; Anisotropic structures
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    Pure and applied geophysics 118 (1980), S. 1228-1231 
    ISSN: 1420-9136
    Keywords: Synthetic seismograms ; Diffracted waves ; Core-mantle boundary
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    Topics: Geosciences , Physics
    Notes: Summary To derive the structure of the Lower Mantle, observations of P and S waves at epicentral distances beyond 90 degrees have been used. The arrival times and amplitude decay with distance proved to be a source of information to derive the structure near the core-mantle interface. These observations were compared with results of theoretical calculations based on full wave theory [1, 2, 5, 6]. Another important theoretical method is the reflectivity method [4]. Differences between the two methods have a direct bearing on the interpretation of the observations and therefore need to be investigated. In the two methods the wave propagation involved in diffraction is simulated in different ways. In this paper the importance of approximations involved in each of the methods will be discussed. For this purpose the calculation of the frequency-dependent decay with distance of diffracted SH waves has been chosen. The approximations are considered to be important both in P and SH diffraction. The advantage of studying SH waves is the simpler and more straightforward formulation.
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    Pure and applied geophysics 118 (1980), S. 1234-1247 
    ISSN: 1420-9136
    Keywords: Theoretical seismograms ; Body-wave spectrum ; Focal depth
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    Notes: Summary The SH body-wave spectrum of a deep earthquake, which occurred at the foot of the Kamchatka peninsula and was recorded in the Solomon Islands, presents a regular modulation. The distribution of minima in the amplitude spectrum, corresponding to jumps in the phase spectrum, conforms with that expected from the interference between direct and surface reflected waves. The strong dependence of the modulation on the focal depth, emerging from theoretical SH body wave spectra obtained with the contribution of the first 21 higher Love-wave modes, was used to investigate the focal depth of the event here considered. The value estimated, 140 km, agrees with an earlier focal depth determination by travel time data.
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    Pure and applied geophysics 118 (1980), S. 1248-1271 
    ISSN: 1420-9136
    Keywords: Earthquake source ; Stress drop model ; Computed near-field accelerograms
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    Topics: Geosciences , Physics
    Notes: Abstract Shallow strike slip earthquakes on vertical faults are modelled as two-dimensional antiplane strain ruptures in a uniformly prestressed homogeneous halfspace. Behind the rupture front, which is specified, the stress drops to a lower value. The elastodynamic boundary value problem is solved with a finite difference method. Several cases are studied, which include symmetric and one-directional rupture propagation, surface faulting, multiple events, variable rupture velocity, sticking and rebreaking of the fault plane. The time function of displacement, velocity and acceleration are interpreted as signals generated by events in the focus, namely starting, stopping and breaking through the surface of the rupture. The model explains peak velocity and peak acceleration in the near field of M≈5.5–6 earthquakes; which are typically about 0.2 m/s and 5 m/s2 at 10 km epicentral distance, if the rupture velocity is close to the shear wave velocity. Sticking of the fault does not alter the accelerograms significantly, but it increases the seismic moment in simple events and decreases it in multiple events.
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    Pure and applied geophysics 118 (1980), S. 1326-1328 
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    Pure and applied geophysics 118 (1980), S. 1293-1309 
    ISSN: 1420-9136
    Keywords: Theoretical seismograms ; Solid-liquid interface ; Core-mantle boundary ; Diffraction and scattering
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    Topics: Geosciences , Physics
    Notes: Abstract The paper discusses basic ideas and principles underlying methods, which have proved useful in the interpretation of diffraction and scattering phenomena by a smooth or slightly rough solid-liquid interface. Generally, the wave interaction may be formulated as an excitation problem; it involves (1) finding an equivalent dislocation or source distribution on the interface, and (2) evaluating the excited wave field. These steps are taken through perturbation theory and/or adopting the appropriate generalization of ray theory. In this context an explicit form of Green's function is also given. The methods have been applied to the core-mantle boundary, with a view toward the interpretation of recent data: (a) diffracted P and S waves around the core (in particular, their attenuation); (b) scattered short-period core phases (in particular, precursors to PKP and PKKP). Other types of wave interaction, and implications for models of the core-mantle boundary structure, are briefly mentioned.
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    Pure and applied geophysics 118 (1980), S. 1272-1292 
    ISSN: 1420-9136
    Keywords: Theoretical seismograms ; Diffracted waves ; Ray parameters ; Core-mantle boundary
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    Notes: Abstract The derivation of P and S velocities at the core-mantle boundary (CMB) from long-period diffracted waves by the use of the simple ray-theoretical formulav CMB=r c /p (v CMB=velocity at the CMB;r c =core radius;p=ray parameter) yields apparent velocity values which differ from the true velocities. Using a dominant period of about 20 sec for calculating theoretical seismograms, we found a linear relation between the apparent velocity and the average velocity in a transition zone at the base of the mantle with fixed velocity on top. The ray parameters determined from long-period earthquake data are found to be 4.540±0.035 and 8.427±0.072 sec/deg for Pdiff and Sdiff, respectively. These values yield apparent velocities of 13.378±0.103 for P and 7.207±0.062 km/sec for S waves. By means of the theoretical relation between apparent and average velocity and under the assumption of linear variation of velocity with depth, one can invert the apparent velocities into true CMB velocities of 13.736±0.170 and 7.320±0.124 km/sec. These results imply positive velocity gradients at the base of the mantle and hence no significant departures from adiabaticity and homogeneity.
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    Pure and applied geophysics 118 (1980), S. 1310-1325 
    ISSN: 1420-9136
    Keywords: Seismic refraction profile ; Caledonides ; Norway ; Low-velocity zone
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    Topics: Geosciences , Physics
    Notes: Abstract Data from a reversed seismic crustal profile crossing the Caledonides of southern Norway suggest a continuously increasing P-wave velocity followed by a low-velocity zone extending from a depth of about 14 km downwards. Interpretation of observed travel time and amplitude characteristics leads to a thickness of 4 km and velocity of 6.0 km/s for this layer, the velocity above and below it being about 6.6 km/s. The role of such a velocity inversion is discussed in the tectonic framework of the Caledonian orogeny and other relevant geophysical information, and it is suggested that the low-velocity zone materializes deep-seated sediments under Precambrian crystalline rocks. The structure of the lower crust is more tentatively established, but still in reasonable agreement with other seismic investigations in the general profiling area.
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    Pure and applied geophysics 118 (1980), S. 1329-1329 
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    Pure and applied geophysics 118 (1980), S. 1329-1329 
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    Pure and applied geophysics 118 (1980), S. 695-705 
    ISSN: 1420-9136
    Keywords: Ozone ; Photochemistry ; System modelling ; Transport
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    Topics: Geosciences , Physics
    Notes: Abstract A scheme of a system of physical and chemical processes controlling the production, transport and destruction of ozone and its gaseous catalysts, as well as other related gases in the low and high stratosphere is presented. An account is made of temperature variations of the stratospheric layer resulting from changes in ozone content; also included is the effect of temperature variations on photochemical reaction rates and ozone and other gases transport between atmospheric layers. Parameters describing major relations of the system are inferred from the analysis of ozone and trace gas data and from the results of model calculations of interdependence between variations in temperature and ozone content of the layer. An analysis of minor fluctuations of the linearized system shows that photochemical processes are responsible for its aperiodic stability and that gas transport between atmospheric layers destabilizes the system.
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    Pure and applied geophysics 118 (1980), S. 706-719 
    ISSN: 1420-9136
    Keywords: Waves ; Baroclinic ; Influence of static stability on
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The effect of the time change of static stability and wind shear on a two-level quasigeostrophic baroclinic wave is considered. First, by keeping the wind shear as a constant the effect of the increase of static stability is that the amplitude of the temperature wave reaches a maximum first while that of the stream field is still amplifying and, as that of temperature wave reaches a minimum, that of the stream field becomes a maximum, and both are in phase. Next, by keeping the static stability as a constant, a life cycle of disturbance associated with the time change of wind shear is obtained. In this case the maximum amplitude of the wave appears at about 6 days and the life cycle is about 11 days for reasonable values of the model parameters. Finally, both effects are considered. The results show that as the wind shear decreases, the static stability increases, and the percentage change of wind shear is larger than that of static stability. This paper is not an entirely convincing analysis of the finite amplitude dynamics of an unstable wave in the two-level model, but rather a pedagogically useful approximate theory in which the retention of some terms rather than others is justified in view of the plausibility of the results.
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  • 188
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    Pure and applied geophysics 118 (1980), S. 720-742 
    ISSN: 1420-9136
    Keywords: Condensation ; Effect of entrainment on ; Cloud drops, condensation of
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract This paper examines the effects of the mixing of dry air into a cloud top from the point of view of the droplet spectra. It is shown theoretically that the resulting cycling of the air up and down in the cloud, as seems to be the essential mechanism by which cumuli have been diluted to their observed liquid water mixing ratio, can double the largest drop radius and generate cloud parcels containing drops of all sizes up to this maximum. These changes in the droplet distribution with size occur by a process which is not greatly influenced by the cloud condensation nuclei or the details of droplet growth since ‘maritime’ like spectra can develop in ‘continental’ type cumuli. It shows that large numbers of cloud condensation nuclei should not have much effect in inhibiting the rainforming process by reducing coalescence growth. On the contrary, the controlling parameters which determine precipitation efficiency and times seem to be those which control the mixing.
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  • 189
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    Pure and applied geophysics 120 (1982), S. 54-66 
    ISSN: 1420-9136
    Keywords: Atmospheric radioactivity ; Wind erosion ; Resuspension rate ; Vegetation contamination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A method for the determination of resuspension parameters of radioactive fall-out from nuclear explosions, deposited on soil from the stratospheric reservoir, is presented. The seasonal variation ofk α-137Cs resuspension parameter, the trend ofk α with time in 1963–1978, the trend over this period of time of the wind component fraction of the concentration of global137Cs in the surface boundary layer over arable and natural soils are given. An estimate of radioactive contamination of vegetation by the effect considered is given as an example of practical use of this work.
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  • 190
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    Pure and applied geophysics 120 (1982), S. 108-116 
    ISSN: 1420-9136
    Keywords: Atmospheric electricity ; Fair weather electric field ; Effect of pollution on potential gradient in atmosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The measurement and monitoring of atmospheric pollutants is an important aspect of pollution studies. A novel method of assessment of the level of pollution in the atmosphere is conceived using point discharge and potential gradients. The present paper is an attempt to show that measurement of the point discharge current (PDC) and potential gradient (PG) can be used to provide information regarding the nature of charges and level of pollution in the atmosphere. The measurement of the PDC and PG in different localities is presented and discussed.
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  • 191
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    Pure and applied geophysics 120 (1982), S. 151-166 
    ISSN: 1420-9136
    Keywords: Source mechanisms ; Rock mechanics ; Microcracks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Focal mechanisms for 116 acoustic emission events associated with uniaxial cyclic loading of Westerly granite have been investigated using P-wave first-motions. Polarities were observed at eight transducers positioned on the sample to provide good azimuthal coverage. The P-wave radiation patterns can be fit by a quadrupole source but not by a simple pure tensional source. The predominant orientations of the two nodal planes for the quadrupole fit were subparallel to and perpendicular to the σ1 direction. Events with ‘close’ hypocenters, i.e., within a radius of 3 mm, display a remarkable similarity in focal mechanisms irrespective of the cycle or time within a cycle at which they occur. The polarity observations of 48 of 116 acoustic emission events could be fit with the simple quadrupole indicating that the microfracturing processes even in uniaxial compression often simplistically portrayed as propagating axial cracks are indeed quite complex.
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  • 192
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    Pure and applied geophysics 120 (1982), S. 167-185 
    ISSN: 1420-9136
    Keywords: Corsica ; Historical seismicity ; Macroseismic study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Description / Table of Contents: Abstract The documents that we have compiled (archives, newspaper reports and seismic catalogues) enabled us to go back to the end of the 18th century in the seismic history of Corsica. The number of felt earthquakes (epicentres off shore or on the island) which were documented during the two and a half centuries is relatively low. Maximum intensities have reached VI or rarely VII. The seismic activity is mainly located in the North-East of Corsica, near faults which have recently been active between the ‘Corse schisteuse’ (Alpine domain) and the ‘Plaine Orientale’ (Quaternary, Neogene). A seismic crisis happened recently (1978–1979) in this area where present activity of some of these faults has been suggested. Macroseismic studies have been conducted for the main shocks (I max=VI and V) in order to locate them accurately. Two among them (April 3, 1978 and March 27, 1979) are studied here in detail. Using the Kövesligethy formula hypocenters are respectively found at 4.5±0.5 km and around 5 km, whereas the corresponding absorption factors are 0.020 and 0.031. Such depths show that the two events affected the upper crust of Corsica (30 km).
    Notes: Résumé L'étude des documents (archives, presse et catalogues sismiques) que nous avons consultés, nous a permis de remonter jusqu'à la fin du XVIIIe siècle dans l'histoire sismologique corse. Le nombre des séismes ressentis (épicentres en mer ou sur l'île) recensés pendant ces deux siècles et demi est relativement faible. Les intensités maximales ont parfois atteint le degré VI, plus rarement VII. L'activité sismique touche principalement une région située au Nord-Est de la Corse, au voisinage de failles au rejeu récènt et séparent le domaine de la Corse schisteuse (alpin) du domaine de la Plaine Orientale (Quaternaire, Néogène). Une crise sismique récente (1978–1979) a de nouveau secoué cette même région où on a suggéré l'activité actuelle de certaines de ces failles. Les plus importants de ces séismes (I max=VI et V) ontifait l'objet d'enquêtes macrosismiques qui permettent d'en préciser les épicentres. Deux d'entre-eux ont été étudiés en détail (3 avril 1978 et 27 mars 1979); en utilisant la relation de Kövesligethy, les hypocentres se situent respectivement à 4,5±0.5 km et vers 5 km, pour des coefficients d'absorption de 0,020 et 0,031. Ces profondeurs indiquent que ces deux séismes ont mis en jeu des éléments superficiels de la croûte corse (30 km).
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  • 193
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    Pure and applied geophysics 120 (1982), S. 229-248 
    ISSN: 1420-9136
    Keywords: Meridional transport ; Monsoon ; Sensible heat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Spherical harmonic analysis is made of the grid point values of geopotential heights at 700 mb and 300 mb levels for the months April to August for the years 1967 and 1972. The year 1967 is a good monsoon year and 1972 is a bad monsoon year in India. Meridional transport of sensible heat is obtained in wave number domain using spherical harmonic coefficients at 500 mb level form=1 to 10 andn−m=0 to 10, wherem represents the wave number round the globe andn−m gives the numbers of zero points from north pole to south pole excluding the poles themselves. Large northward transports of sensible heat in the month of May and in the monsoon months at the subtropics are characteristic of bad monsoon. Wave 1 transports sensible heat southward (forn−m=0) and wave 2 transports sensible heat northward (forn−m=4). Strengthening of wave 1 is conducive to good monsoon year and strengthening of wave 2 is conducive to bad monsoon year. These are the same features obtained in Fourier analysis. The contrasting features exist in waves 1 and 2 both in good and in bad monsoon and are better defined in the present analysis than in the Fourier analysis of the earlier study. However, waves 1 and 2 reveal clearer contrast in the present analysis than in the Fourier analysis. Bad monsoon activity is associated with large divergence of heart at subtropics and large convergence of heat at extra tropics.
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  • 194
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  • 195
    ISSN: 1420-9136
    Keywords: Fourier transform method ; Self-potential anomalies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The self-potential anomaly due to a two-dimensional inclined sheets of finite depth extent has been analysed in the frequency domain using the Fourier transform. Expression for the Fourier amplitude and phase spectra are derived. The Fourier amplitude and phase spectra are analysed so as to evaluate the parameters of the sheet. Application of this method on two anomalies (synthetic and field data) has given good results.
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  • 196
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    Pure and applied geophysics 120 (1982), S. 422-436 
    ISSN: 1420-9136
    Keywords: Monex-79 ; Objective analysis ; Wind field
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The monsoon sub-programme of FGGE deployed a variety of observing systems such as research aircraft, research vessels, floating ballooms, and a geostationary satellite, etc. during the special observational period of Monex-79, with a view to making the best possible data set available for studies on various aspects of the monsoon circulation. Whether the data obtained from the various observational platorms improve the representation of the monsson systems, flow patterns, etc. in the analysis is the basis of this study. For this, the objective analyses of the wind field were made with different data sets, first using only the data from conventional observation platforms, subsequently including the data from aircraft and ships and then finally including the data from the satellite. These analyses were compared with carefully made subjective analyses. It is inferred that the addition of data has a positive impact on the objective analysis and the improvement in the analysis is more marked in the data-void region like the Arabian Sea compared to the region where observational stations are distributed fairly stisfactorily. It is also inferred that the impact of the aircraft/ship data on the analysis is more consistent than the data from the satellite.
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  • 197
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    Pure and applied geophysics 120 (1982), S. 483-494 
    ISSN: 1420-9136
    Keywords: Flood ; Precipitation ; Tropical meteorology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The rainstorm of 17 to 21 July 1981 which caused exceptionally heavy rains and floods in arid Rajasthan, was analysed. It was observed that 7 stations in the rainstorm area broke their previous 80-year record of one-day rainfall, and two of these stations equalled their respective estimates of probable maximum precipitation (PMP). A comparison of areal raindepths of this rainstorm with the similar raindepths of past severe-most rainstorms of this region showed that this rainstorm gave unprecedented raindepths up to about 38 850 sq. km (i.e. 15 000 sq. miles) for a 3-day duration.
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  • 198
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    Pure and applied geophysics 120 (1982), S. 495-502 
    ISSN: 1420-9136
    Keywords: Cloudiness ; Sunshine ; Tropical meteorology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The relationship between point cloudiness and sunshine derived cloud cover in India is investigated using data collected from 33 stations. It has been found that point cloudiness, in general, overestimates sunshine derived cloud cover. The latitudinal dependence of the overestimation is discussed. The significance of the precise quantification of cloudiness in radiation budget studies is briefly mentioned.
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  • 199
    ISSN: 1420-9136
    Keywords: Wave scattering ; Elastic heterogeneity ; Three-dimensional modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The formal solutions of displacement field to the problem of elastic wave scattering and diffraction due to an infinitely long rigid cylinder embedded in an infinite elastic medium by an impulsive point source have been obtained in the integral form. The integrals for the reflected and the diffracted waves both in the shadow zone and in the illuminated zone are evaluated asymptotically for the early time motion by the Reisdue-Cagniard method and the Saddle-point-Cagniard method. Numerical results of the diffractedP, S andPS waves at a fixed circum-distance from the surface of the rigid cylinder show noticeably that (1) the energy partition for the diffractedS wave is small in comparison with that for the diffractedP wave, (2) the wave form of the diffractedS wave is broader and more diffused than that of the diffractedP wave, (3) the direction of the radial motions of the diffractedP andS waves varies as a function of the observational point, and (4) the energy partition for the diffractedP wave is much smaller than that for the direct or the reflectedP waves.
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  • 200
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    Pure and applied geophysics 120 (1982), S. 642-647 
    ISSN: 1420-9136
    Keywords: Atmospheric kinetic energy ; Climate models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The winter simulations of the GLAS climate model and the NCAR community climate model are used to examine the maintenance of the atmospheric kinetic energy. It is found that the kinetic energy is generated in the lower latitudes south of the maximum westerlies, transported northward and then, destroyed in the midlatitudes north of the maximum westerlies. Therefore, the atmospheric kinetic energy is maintained by the counterbalance between the divergence (convergence) of kinetic energy flux and generation (destruction) of kinetic energy in lower (middle) latitudes.
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