Wind tunnel modeling of small-scale meteorological processes

After introductory remarks on similarity laws to be satisfied in wind tunnel experiments simulating small-scale meteorological processes, mean and turbulence characteristics of wind tunnel boundary layers are presented and compared with the characteristics of the atmospheric boundary layer. The results are used to evaluate the possibilities and limitations of physical modeling of pollutant dispersion in general. In the second part of the paper, the potential of wind tunnels to solve micro-meteorological problems of real practical interest will be demonstrated. The example involves the investigation of the effects of building downwash on ground-level concentrations for flue gases discharged from natural draft wet cooling towers.     

Thermal comfort of man in different urban environments

Summary On July 29, 1985, a hot summer day, biometeorological measurements were performed simultaneously in three different urban structures within the city of Munich and in the trunk space of a nearby tall spruce forest. Based on the results of these experiments the following thermophysiologically relevant biometeorological indices were calculated: Predicted mean vote, skin wettedness and physiologically equivalent temperature. These three indices are derived from different models for the human energy balance. They allow the assessment of the thermal components of the microclimates at the selected sites with regard to application in urban planning. The results quantitatively show the great heat stress in the urban structure street canyon, exposed to south, whereas in the trunk space of the tall spruce forest there is nearly an optimal climate even on hot summer days. Between these extremes the results for street canyon, exposed to north show a little higher heat load than for backyard with trees.

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Zusammenfassung An einem heißen Sommertag, dem 29. Juli 1985, wurden in drei Stadtstrukturen in München und im Stammraum eines nahegelegenen Fichtenhochwaldes zeitgleich biometeorologische Messungen durchgeführt. Mit den Meßergebnissen wurden folgende thermophysiologisch relevante biometeorologische Indizes berechnet: Predicted mean vote, Hautbenetzungsgrad und physiologisch äquivalente Temperatur. Diese drei Indizes beruhen auf verschiedenen Modellen zur menschlichen Energiebilanz. Mit den drei Indizes wurden die thermischen Komponenten der Mikroklimate an den ausgewählten Meßplätzen im Hinblick auf Stadtplanungsaufgaben bewertet. Die Ergebnisse zeigen quantitativ die relativ große Hitzebelastung bei der Stadtstruktur Straßenschlucht, nach Süd exponiert, während im Stammraum des Fichtenhochwaldes selbst an heißen Sommertagen nahezu optimale Bedingungen herrschen. Zwischen diesen Extremen liegen die Ergebnisse für die anderen Meßplätze, wobei für Straßenschlucht, nach Nord exponiert die Wärmebelastung etwas höher als für Innenhof mit Bäumen ist.

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With 6 Figures     

Meeresoptische Messungen während schwerer Stürme auf der Forschungsplattform “Nordsee” vom 14. November bis zum 8. Dezember 1980

Ocean Dynamics - Meeresoptische Messungen auf der Forschungsplattform “Nordsee” haben gezeigt, daß dort während schwerer Stürme, hauptsächlich durch den Einfluß...     

Georeference correction on landsat imagery

This paper discusses the geometric anomalies present in bulk images which are being generated on NRSA Data Processing System (DPS). A georeference correction algorithm has been presented to correct geometric scale anomalies in a systematic manner. An approach to generalize and integrate georeference correction algorithm with existing bulk correction program has been realised without crippling the speed of DPS film product generation Software. Limitations and accuracy of the algorithm are discussed.     

Airfreight: Geographical patterns and economics. Forecasting models with an example from Finland

In my paper I will try to give some geographical and economical aspects on the recent development of airfreight.Some models for forecasting will be presented, especially three made by (i) DOUGLAS Aircraft's RD; (ii) IATA Freight Traffic Forecasts and (iii) A trend model modified in my department. These three models will be applied and compared with special respect to Finnish airfreights during the 80's.     

Daytime F2-layer positive storm effect at middle and lower latitudes

Daytime F2-layer positive storm effects at middle and lower latitudes in the winter thermosphere are analyzed using AE-C, ESRO-4 neutral gas composition data, ground-based ionosonde observations and model calculations. Different longitudinal sectors marked by the storm onset as ‘night-time’ and ‘daytime’ demonstrate different F2-layer positive storm mechanisms. Neutral composition changes in the ‘night-time’ sector with increased [O] and [N₂] absolute concentrations, while (N₂/O)_storm/(N₂/O)_quiet\approx1 at F2-layer heights, are shown to contribute largely to the background N_mF2 increase at lower latitudes lasting during daytime hours. Storm-induced surges of the equatorward wind give rise to an additional N_mF2 increase above this background level. The mid-latitude F2-layer positive storm effect in the ‘daytime’ sector is due to the vertical plasma drift increase, resulting from the interaction of background (poleward) and storm-induced (equatorward) thermospheric winds, but not to changes of [O] and [N₂] concentrations.     

A comparison of total precipitation values estimated from measurements and a 1D cloud model

The purpose of this study is to establish a relation between observed total precipitation values and estimations from a one-dimensional diagnostic cloud model. Total precipitation values estimated from maximum liquid water content, maximum vertical velocity, cloud top height, and temperature excess are also used to provide an equation for the total precipitation prediction. Data for this study were collected in Istanbul during the autumns of 1987 and 1988. The statistical models are developed with multiple regression technique and then comparatively verified with independent data for 1990. The multiple regression coefficients are in the range of 75% to 80% in the statistical models. Results of the test showed that total precipitation values estimated from the above techniques are in good agreement, with correlation coefficient between 40% and 46% based on test data for 1990.     

Climate change scenarios: Comparisons of paleoreconstructions with recent temperature changes

Paleoclimatic reconstructions for the Mid-Holocene, Eemian, Mid-Pliocene and the Last Glacial Maximum are used to test the paleoanalog hypothesis and develop a regional climate change scenario based on a linear scaling by one parameter - the mean Northern Hemispheric temperature change with respect to present, ΔT _NH. The empirical verification of the paleoanalog hypothesis is extended to a cold epoch for zonal means and to regional distributions of temperature in warm epochs. The best agreement among the scaled paleoanomalies from different epochs is obtained if the seasonal temperature anomalies are scaled with ΔT _NH of the corresponding season. Preferential areas are identified where the paleoanalog hypothesis works relatively well; these areas coincide with the areas of the most pronounced warming. It is shown that the geographical distributions of the winter temperature anomalies over land in the paleodata are similar to those in the 1980–1990 period. From the three warm epochs, a paleodata-based scenario is deduced for the spatial distribution of temperature in a future climate, on the scale of continents. The conditions under which scenarios based on paleodata can be applied are discussed.     

High resolution time series of lead and zinc in sediments of Lake Constance

Sediments in Lake Constance have been dated by radiometric methods and lamination counting. Investigations into the concentrations of lead and zinc in the sediments were carried out to get detailed information about environmental history. Maximum concentrations were found at the beginning of the 1960's. The lead maximum contamination occurred 3 years before the zinc maximum and has an unidentified source. The use of coal, leaded gasoline or the remobilization within the sediment could be excluded to result in the lead maximum. The fluctuations in zinc contamination could be explained with increasing and decreasing pollution (industry, coal burning, building of sewage plants). The greatest fluctuations of both metals occur during periods of great change in the economic history of Germany.