Das Projekt "Modellierung der Auswirkungen der Degradierung des Bodens auf das Klima" wird vom Umweltbundesamt gefördert und von Potsdam-Institut für Klimafolgenforschung e.V. durchgeführt. General Information: The Mediterranean region has experienced drastic changes in land use and climate in the last century. Some of these changes are still occurring. Modelling studies have shown that rainfall in particular may be strongly related to antecedent soil moisture and that the land surface plays a critical role in determining size and location of the rain events. Critical is how a long term drought will exacerbate or extend the aridity of a region. This study will focus on the climatic effects of land degradation in the Mediterranean and the Sahel, the latter area already subject to severe land degradation. A combination of GCM and Regional scale modelling will be used to better understand the climate response to land degradation and will try to assess the uncertainty involved in current climate forecast as well as the relative role of the ocean versus the land surface in forcing the climate. Datasets from the series of land surface experiments in semi-arid areas (EFEDA, HAPEX-Sahel) will be used to calibrate, improve and test the models. OBJECTIVES: - to understand the climatic responses associated with land cover ' change ' in semi-arid regions, particularly land surface degradation, and thus the causes of persistent drought. - To understand the relative influences of Sea surface temperature anomalies and land cover change on likely climate variability in the Mediterranean and the Sahel. - Investigate the influence of scale and degree of degradation on the climatic response. METHODOLOGY: Three of the major Global Climate Models in Europe (and one from the USA) plus two Regional Climate Models will be used. To intercompare the results from these models the land surface schemes will be calibrated and tested with common sets of land surface data from the EFEDA and HAPEX-Sahel field experiments. Also common land cover classifications and desertification scenarios will be developed. Model integrations will be made using sea surface temperature patterns from extreme wet and dry years. Questions of scale will be tackled, firstly, by simulating effect in the Sahel (continental scale) and the Iberian Peninsula (regional scale), secondly, by investigating partial desertification and, finally, by using regional and global climate models. The project will increase our understanding of the climate system, improve climate models, provide a better understanding of climate variability and develop the scientific foundation for rational management of land resources in parts of Europe threatened by desertification. Prime Contractor: Natural Environment Research Council, Institute of Hydrology; Crowmarsh-Gifford; UK.
Das Projekt "Wuestenbildungsprozesse im Mittelmeerraum und deren Wechselbeziehungen zum globalen Klima, Untergruppe IV: Aerologie und Messungen mit Flugzeugen" wird vom Umweltbundesamt gefördert und von Universität Karlsruhe, Institut für Meteorologie und Klimaforschung durchgeführt. Further analysis of the boundary layer data measured during the EFEDA I field campaign will be carried out to reduce the uncertainties in the estimation of the energy and water budget vapour at the Earth surface. A comparison of surface fluxes derived from other systems (ground-, remote sensing- and model data) will be, also, done. The variety of results of the EFEDA I field phase provided by different systems and teams will be compared in order to achieve maximum knowledge about the advantages and disadvantages of the used evaluation methods and the quality of the experimental programme, eg the software, providing turbulent fluxes used by different teams will be intercompared exemplary with the help of single flight paths of each aircraft. A final assessment of all available results will be taken as a basis for the design of a research strategy for the EFEDA II field campaign. An experimental plan containing several flight programs addressed to the main objectives will be discussed and defined. Parallel to the strategic preparations the technical preparations of the EFEDA II field phase will take place. New sensors or sensor packages will be tested and the results or problems will be discussed between the responsible technicians and scientists. Especially a new sensor package operated by a helicopter (helipot) will be tested. Ground calibrations and tests of new components, execution of quality assurance/quality control experiments as well as intercalibration flights will be made. In particular, an intercomparison flight over a flat horizontally homogeneous area is planned for intercomparison of the turbulence systems besides an intercomparison of aircraft equipment with a meteorological tower. Finally the EFEDA II field campaign data will be analysed to accurate area averaged fluxes over the experimental area.
Das Projekt "Wuestenbildungsprozesse im Mittelmeerbereich und ihre Wechsselbeziehungen zum globalen Klima - Untergruppe V: Fernerkundung und radiometrische Oberflaecheneigenschaften: Auswertung des Fortschreitens der Wuestenbildung aus dem Weltall" wird vom Umweltbundesamt gefördert und von Freie Universität Berlin, Institut für Meteorologie WE03 durchgeführt. This first part of the project deals with the calibration and intercalibration of remote sensing data (NOAA-AVHRR and LANDSAT images), gathered during the EFEDA 1991 field experiment and the application of corrections for aspect angle, surface emissivity, and atmospheric effects. Data from other observation systems will be included as they become available. The accuracy of the inferred informations is determined by intercomparisons with ground based measurements made under controlled conditions. Surveys will be carried in the experimental area to obtain more information about the angular distribution of the reflected solar radiation over the different plant communities in dependence of the physiological and structural parameters of the plant-soil systems. A major effort will be made to relate directional reflectances, surface temperatures and vegetation indices derived from the spectral measurements made in space to energy and water fluxes between the surface and the atmosphere measured by the EFEDA flux groups and vegetation parameters observed at the surface by the EFEDA vegetation group. The second part of the project deals with the determination of area averages and the study of temporal changes. Validated information derived from the satellite data will be scaled up into a size comparable with the grid width of global models to support the determination of energy and water exchanges between the surface and the atmosphere, and the definition of a desertification index based on satellite observations. For this purpose time series of these data will be analysed with respect to interannual changes related to the weather development and possible trends. An attempt will be made to correlate cumulative annual data of vegetation index with biomass production. The broadening of the geographical scope of EFEDA will be prepared by processing NOAA-AVHRR satellite data for the whole of the Mediterranean coastal zone which can be provided to users with information about the applied corrections and interpretation aids.
Das Projekt "Fernerkundung von Versteppung und Umweltveraenderungen im Mittelmeerraum, Teilprojekt: Kartierung von Landoberflaechenparametern" wird vom Umweltbundesamt gefördert und von Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Institut für Physik der Atmosphäre Oberpfaffenhofen durchgeführt. Die Aggregation von Verdunstungs- und Energie-Fluessen von lokalen auf regionale Skalen wurde im Zusammenhang mit EFEDA unter Nutzung von Daten aus den Kampagnen 1991 und 1994 untersucht. Die Arbeit in RESMEDES zielt darauf ab, die Ergebnissen und Methodologie, die waehrend EFEDA entwickelt wurden, auf groessere Raum- und Zeit-Skalen anzuwenden und weiterzuentwickeln. Die beruecksichtigten Raum-Skalen reichen nun von dem EFEDA Experimental-Gebiet in Castilla-La Mancha bis zur Groesse der ganzen Iberischen Halbinsel. Die Zeit-Skalen wurden von den zwei Wochen dauernden Feldkampagnen auf einen kompletten Jahreszyklus ausgeweitet. Der eigentliche Zweck der DLR-Beteiligung ist es, Daten in diesen beiden Skalen fuer zwei Ziele zur Verfuegung zu stellen: Erstens meteorologische Daten, die als Input fuer verbesserte Algorithmen benoetigt werden, um die Bodenenergiefluesse aus Fernerkundungsinformationen zu berechnen, und zweitens in-situ Flussmessungen und Flugzeug-Fernerkundungsdaten zur Validierung von Fernerkundungsmethoden und regionalen Klimamodellen.