The precipitation series of Gr. St. Bernard and Geneva since 1818     

M. Schüepp 《Theoretical and Applied Climatology》1991,44(2):139-142

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Complete synthetic seismograms for high-frequency multimodeSH-waves     

N. Florsch  D. Fäh  P. Suhadolc  G. F. Panza 《Pure and Applied Geophysics》1991,136(4):529-560

We present an efficient scheme to compute high-frequency seismograms (up to 10 Hz) forSH-waves in a horizontally stratified medium with the mode summation method. The formalism which permits the computation of eigenvalues, eigenfunctions and related integral quantities is discussed in detail. Anelasticity is included in the model by using the variational method. Phase velocity, group velocity, energy integral and attenuation spectra of a structure enable the computation of complete strong motion seismograms, which are the basic tool for the interpretation of near-source broad-band data.Different examples computed for continental structures are discussed, where one example is the comparison between the observed transversal displacement recorded at station IVC for the November 4, Brawley 1976 earthquake and synthetic signals. In the case of a magnitudeM _L =5.7 earthquake in the Friuli seismic area we apply the mode summation method to infer from waveform modeling of all three components of motion of observed data some characteristics of the source.On leave from Institute of Geophysics, ETH, Zürich, Switzerland.  相似文献   

Passive microwave signatures of landscapes in winter   总被引：4，自引：0，他引：4  

C. Mätzler 《Meteorology and Atmospheric Physics》1994,54(1-4):241-260

Summary The successful application of passive microwave sensors requires signatures for the unambiguous inversion of the remote sensing data. Due to the large number of object types and large variability of physical properties, the inversion of data from land surfaces is a delicate and often ambiguous task. The present paper is a contribution to the assessment of multi-frequency passive microwave signatures of typical objects on land in winter. We discuss the behaviour of measured emissivities at vertical and horizontal polarization over the frequency range of 5 to 100 GHz (incidence angle of 50 degrees) of water and bare soil surfaces, grass and snowcovers under various conditions. These data and their variabilities lead us toward a classificaion algorithm for some, but not all object classes. Most snowcovers can easily be discriminated from other surfaces, difficulties occur for fresh powder snow if 94 GHz data are not available. The problem of wet snow has found a solution by using a certain combination of observables.In addition to snowcover types we find large differences between frozen and unfrozen bare soil. On the other hand the different situations of grasscovers show all very similar emissivities.For the estimation of physical parameters we propose algorithms for certain object classes. The estimation of surface temperature, especially for snow-free land, seems to be feasible, also the estimation of the snow liquid water content at the surface. For estimating soil moisture lower frequencies (e.g. 1.4 GHz) should be used.For the estimation of the Water Equivalent, WE, we cannot yet find a definitive solution. Certain correlations exist for dry winter snow between WE and observables at frequencies between 10 and 35 GHz. Especially the polarization difference at 10 GHz shows a monotonous increase with increasing WE. Algorithms using higher frequencies are more sensitive to WE, however, they are subject to ambiguities.With 7 Figures  相似文献   

Effects of climate change on snow accumulation and melting in the Broye catchment (Switzerland)     

Bultot  F.  Gellens  D.  Schädler  B.  Spreafico  M. 《Climatic change》1994,28(4):339-363

The study used a daily step conceptual hydrological model to examine the effects of climate change on snowfall accumulation and on snow cover melting in the Broye catchment (moderate relief- altitude from 400 to 1500 m a.s.l.). Five elevation bands representing a range of climatic conditions were used together with three realistic climate change scenarios based loosely on GCM's predictions and which reflect feasible changes by extending time periods. For a very moderate climate change (rise in air temperature of ca 1 °C), possibly in a near future, the reduction of snow cover duration, mean water equivalent and monthly maximum water equivalent is the most sensitive in the lower part of the catchment and during the first and last months of the snow season. In the higher part of the basin and during the colder months January and February, similar reduction rates can be expected in case of larger climate changes. The floods due to the melting of snow cover are lower. Sometimes rainfall, considered as snow in the present day conditions, generates additional floods during the winter season. For winter sports resorts below 1500 m a.s.l., even the very moderate climatic change scenario (temperature rise around 1 °C) leads to economically very difficult conditions. Finally, a climatic change detection index based on snow cover duration is proposed.  相似文献   

Mean atmospheric circulation patterns associated with major Baltic inflows     

Dr. habil W. Matthäus  Dipl.-Met. H. Schinke 《Ocean Dynamics》1994,46(4):321-339

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Petrographische und Kalium-Argon-Untersuchungen an basischen tertiären Vulkaniten zwischen Westerwald und Vogelsberg     

Dipl.-Min. P. -G. Turk  Prof. Dr. H. -H. Lohse  Dr. K. Schürmann  Dr. U. Fuhrmann  Prof. Dr. H. J. Lippolt 《International Journal of Earth Sciences》1984,73(2):599-617

Between the upper tertiary volcanic areas of Westerwald and Vogelsberg (central Western Germany) occur more than 40 isolated tertiary volcanic dikes, eroded necks, plugs and domes. Twelve of these volcanic rocks have been investigated petrographically and chemically and classified by means of their modal and chemical composition. Additional modal analyses have been performed on seven other volcanics. On seventeen volcanic occurences K-Ar-whole rock age determinations have been made. The K-Ar age determinations yield- with the exception of an olivine-nephelinite — values between 27 and 15 Ma. Regarding the known intervals of volcanic activities of the Westerwald- and Voge1sberg-areas, most of the examined volcanics can be related genetically with one of the adjacent volcanic areas. There seems to be no geographical overlapping of volcanics showing Westerwaldages and Vogelsberg-ages. A possible influence of excess-Ar-bearing phases (e. g. mantle xenoliths) and an Ar-loss of constituent matter of the groundmass have been estimated by additional age determinations of enriched samples. These influences — partially compensating each other — may shift the K-Ar whole rock age to a maximum of 5 % and thus do not exceed the dimension of the standard deviations. A distinct NNE-SSW-striking fault in the region between Marburg and Gießen is situated parallel with the eastern border of the “Rheinisches Schiefergebirge”. Volcanics showing Westerwald-age and Vogelsberg-age respectively reach this fault, but obviously do not overlap it. Relations between rock-type an rock age, as it has been observed for the volcanics of the northern Hessian Depression (Kreuzer et al. 1973;Wedepohl 1982) cannot be proved certainly. On the other hand, similar to the basaltic rocks of the northern Hessian Depression, the youngest volcanic product is an olivine-nephelinite (9 Ma).  相似文献   

Gravity change and land uplift in Fennoscandia 1966–1984     

Martin Ekman  Jaakko Mäkinen  Age Midtsundstad  Ole Remmer 《Journal of Geodesy》1987,61(1):60-64

An analysis is made of the results from all repeated gravity measurements of the Fennoscandian land uplift gravity line 63°. The line is, thereby, divided into two separate parts: one part west of the land uplift maximum, and the other part east of the land uplift maximum. A statistically significant change of gravity is found both for the western part and the eastern one. Both parts give a relation between gravity change and land uplift of about ?0.22μgal/mm.  相似文献   

The Baltic Sea 1994—Consequences of the hot summer and inflow events     

Dietwart Nehring  Wolfgang Matthäus  Hans-Ulrich Lass  Günther Nausch  Klaus Nagel 《Ocean Dynamics》1995,47(2):131-144

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The Baltic Sea in 1995— Beginning of a new stagnation period in its central deep waters and decreasing nutrient load in its surface layer     

Dietwart Nehring  Wolfgang Matthäus  Hans-Ulrich Lass  Günther Nausch  Klaus Nagel 《Ocean Dynamics》1995,47(4):319-327

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Assessing ecological implications of climatic change: Can we rely on our simulation models?     

H. Hänninen 《Climatic change》1995,31(1):1-4

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