Unsymmetrische Regenrunsen

Zusammenfassung Ein Beispiel scharf unsymmetrischer Regenrunsen auf der Halbinsel von San Francisco wird beschrieben; es wird versucht, diese eigentümlichen Kleinformen aus der Exposition, und zwar insbesondere aus dem Einflu\ der eintrocknenden Sonnenbestrahlung auf die Angreifbarkeit des Bodens für lineare Regenwasserspülung zu erklären. Beziehungen zu Denudationsformen mittlerer Grö\enordnung werden angedeutet.     

A new fast fourier method for evaluating fourier spectra at arbitrary frequencies

This paper deals with some recent problems of frequency determination in dynamical systems. As a main result a new Fast Fourier Transform (FIT) method, the High Resolution Fast Fourier Transform (HRFFT) is presented, which allows for economic evaluation of discrete Fourier spectra at arbitrary frequencies, not just at the evenly spaced points of the rigid frequency grid the ordinary FFT is restricted to (continuous evaluation). Comparison is made to existing methods in what regards continuous evaluation, computational speed, memory requirements and precision, evidencing the high efficiency of the HRFFT. Possible applications of the new technique are indicated, showing that existing methods, as e.g. that of Laskar (1990, Icarus 88) and its extension by idlichovský and Nesvorný (1996, this volume), may strongly benefit from the HRFFT.     

Nordhemisphärische Niederschlags-und Temperaturschaukeln

Zusammenfassung Als Niederschlagsschaukeln erweisen sich die Gebiete mit vorwiegenden Konvektionsregen und die benachbarten Bereiche mit häufigeren Advektionsniederschlägen. Erstere befinden sich vorzugsweise im Lee advektiver Luftströmungen. Als Temperaturschaukeln sind im nordhemisphärischen Sommer die Gebiete: nordamerikanische Eismeerküste-mittlere Alaskahalbinsel, nördliches Westsibirien-Gebiet westlich des Nordural anzusehen. Die Ursache liegt in der konträren thermischen Wirkung der zyklonalen Störungen.Summary The regions of prevailing rains of convection and the neighbouring areas with more frequent precipitation of advection prove as «swings of precipitation». The former are to be found preferably in the lee of advectiv winds of air. As «swings of temperature» are to be regarded the following areas in the northern hemispheric summer: Northamerican Polarsea coast-central part of Alaska-Peninsula Northern Westsiberian region westward off the Northern Ural. The cause is to be found in the contrary thermic effect of cyclonic disturbances.     

Precipitation and evaporation budgets over the Baltic Proper: observations and modelling

Precipitation and evaporation budgets over the Baltic Sea were studied in a concerted project called PEP in BALTEX (Pilot study of Evaporation and Precipitation in the Baltic Sea), combining extensive field measurements and modelling efforts. Eddy-correlation-measurements of turbulent heat flux were made on a semi-continuous basis for a 12 month period at four well-exposed coastal sites in the Baltic Proper (the main basin of the Baltic Sea). Precipitation was measured at land-based sites with standard gauges and on four merchant ships travelling between Germany and Finland with the aid of specially designed ship rain gauges (SRGs). The evaporation and precipitation regime of the Baltic Sea was modelled for a 12 month period by applying a wide range of numerical models: the operational atmospheric High Resolution Limited Area Model (HIRLAM, Swedish and Finnish versions), the German atmospheric REgional-scale MOdel, REMO, the operational German Europe Model (only precipitation), the oceanographic model PROBE-Baltic, and two models that use interpolation of ground-based data, the Swedish MESAN model of SMHI and a German model of IFM-GEOMAR Kiel. Modelled precipitation was compared with SRG measurements on board the ships. A reasonable correlation was obtained, but the regional-scale models and MESAN gave some 20% higher precipitation over the sea than is measured. Bulk parameterisation schemes for evaporation were evaluated against measurements. A constant value of C_HN and C_EN with wind speed, underestimated large fluxes of both sensible and latent heat flux. The limited area models do not resolve the influence of the height of the marine boundary layer in coastal zones and the entrainment (on the surface fluxes), which may explain the observed low correlations between modelled and measured latent heat fluxes. Estimates of evaporation, E, and precipitation, P, for the entire Baltic Proper were made with several models for a 12 month period. While the annual variation was well represented by all predictions, there are still important differences in the annual means. Evaporation ranges from 509 to 625 mm year^-1 and precipitation between 624 and 805 mm year^-1 for this particular 12 month period. Taking the results of model verification from the present study into account, the best estimate of P-E is about 100 ± 50 mm for this particular 12 month period. But the annual mean of P-E varies considerably from year to year. This is reflected in simulations with the PROBE-Baltic model for an 18 year period, which gave 95 mm year^-1 for the 12 month period studied here and 32 mm year^-1 as an average for 18 years.     

The global-average production rate ofBe

Precipitation collected in continuously open containers for about a year at seven sites around the United States was analyzed for¹⁰Be,⁹⁰Sr,²¹⁰Pb and²³⁸U. Based on these data and long-term precipitation,⁹⁰Sr and²¹⁰Pb delivery patterns, the stratospheric, tropospheric and recycled¹⁰Be components in the collections were estimated and the global¹⁰Be production rate was assessed. Single station production rate estimates range from 0.52 × 10⁶ atoms cm⁻² yr⁻¹ to 2.64 × 10⁶ atoms cm⁻² yr⁻¹. The mean value is 1.21 × 10⁶ atoms cm⁻² yr⁻¹ with a standard error of 0.26 × 10⁶ atoms cm⁻² yr⁻¹.     

Observations of Minor Planets

We represent 266 positions of 77 minor planets determined from plates taken in 1972 and in 1979–1980 with the Schmidt telescope 1340/2000/4000 of KARL SCHWARZSCHILD Observatory Tautenburg.     

Seismic scale saturation relations in turbidite reservoirs undergoing waterflood

Estimates of the effective fluid modulus from seismic cannot be directly converted to the true pore-volume weighted mean saturation     determined from fluid flow principles by using the saturation laws currently in use. One of the reasons is that seismic waves sample the reservoir geology and production induced saturation heterogeneity in a different way from the fluids. This mismatch prevents accurate quantitative evaluation of saturation changes from 4D seismic analysis. To tackle this problem, a reservoir-related saturation law is developed for a turbidite reservoir – this geology being chosen because the architecture for a single sand package can be modelled as a stack of horizontal beds. An effective medium and perturbation theory are applied to the determination of the seismic properties of this model. This calculation provides a relationship that connects the true saturation     to the effective fluid modulus from seismic via statistical measures of the vertical spread of the porosity and saturation variations in the reservoir. These statistics can be extracted from the simulation model and if known, enable the new saturation law to deliver a significant improvement in accuracy when estimating     compared to other well-known laws. The relationship that has been developed also captures the effect of inter-bedded shales and can therefore be used to estimate true saturation in regions of the reservoir with moderate to low net-to-gross, provided the fraction of the shale component is known. In practice, the final choice of saturation law depends upon the reservoir information available, the assumptions that can be tolerated and the accuracy required in any particular reservoir characterization study.