A FIVE YEAR PRECIPITATION CLIMATOLOGY IN THE DANUBIAN WATERSHED BASED ON METEOSAT DATA

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1 A FIVE YEAR PRECIPITATION CLIMATOLOGY IN THE DANUBIAN WATERSHED BASED ON METEOSAT DATA C. Reudenbach and T. Nauss Laboratory for Climatology and Remote Sensing LCRS Department of Geography, University of Marburg, Deutschhausstr. 10, D Marburg, Germany ABSTRACT Water affects all economic, cultural, social and ecological aspects of daily life and hence forms the basis for a stable environment. Therefore Geographers, Hydrologists, Economists, Psychologists etc. have joint together to the GLOWA-Danube project to implement an integrative Global Change Decision Support System called DANUBIA for the km 2 upper Danube collection area in order to investigate ways of sustainable future water use. The GLOWA-Danube project is part of the German programme on Global Change in the Hydrological Cycle funded by the German Federal Ministry of Education and Research (BMBF). The authors implemented a satellite based rainfall retrieval for Meteosat in the Java environment of DANUBIA called Advective-Convective-Technique. The poster shows results of an almost continuous five years period of precipitation. 1. OUTLINE OF THE ADVECTIVE-CONVECTIVE TECHNIQUE (ACT) A new modular retrieval scheme, the Advective-Convective-Technique (ACT) has been developed. It consist of three modules which deal with precipitation retrieval from convective core areas, from advective cloud regions and an enhanced classification scheme for precipitating clouds by using cloud microphysical properties. Because the first two modules only require brightness-temperatures from the infrared (TBIR) and water vapour (TBWV) channels, they can be used to investigate existing long time series of geostationary data (e.g. Meteosat). However, the increased spectral resolution of the latest generation of geostationary satellites (especially spectral bands at 0.6, 1.6 and 3.9 µm) is necessary for the third module. Figure 1 presents the principal outline of the ACT scheme. The ACT algorithm can be applied to almost every optical satellite system as long as it provides at least one water vapour and one infrared channel. However, a new cloud microphysics module could be implemented due to the increased spectral resolution of recent geostationary satellite sensors (Reudenbach et al. 2001, Reudenbach 2003, Nauss et al. 2003, Reudenbach et al. 2004).

2 Figure 1. Overview of the ACT algorithm. 2. MONTHLY AMOUNT OF PRECIPITATION IN THE DANUBIA AREA The following images show the monthly amount of precipitation per 1 km square pixel for the upper Danube catchment area. Figure 2 shows the monthly mean rainfall within the modell area compared to interpolated stationdata values. Figure 2. Monthly mean rainfall within the upper Danube catchment area retrieved by the ACT algorithm using Meteosat data and a station data interpolation model (Ludwig 2003).

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7 Figure 3. Monthly mean rainfall within the upper Danube catchment area retrieved by the ACT algorithm using Meteosat data. 3. ACKNOWLEDGEMENTS Parts of the research described in this paper are funded by the Erich-Becker foundation (formerly Frankfurt Airport Foundation), a foundation of the Fraport AG for the promotion of science and research and by the German Federal Ministry of Education and Research as part of the German programme on global change in the hydrological cycle (GLOWA-DANUBE, Grant No. 07 GWK 04).

8 4. REFERENCES NAUSS, T., M. WAGNER & J. BENDIX 2003: Operational Retrieval of Microphysical Properties from dayand night-time MSG Data Eumetsat Meteorological Satellite Conference. LUDWIG, R., W. MAUSER, S. NIEMEYER, A. COLGAN, R. STOLZ, H. ESCHER-VETTER, M. KUHN, M. REICHSTEIN, J. TENHUNEN, A. KRAUS, M. LUDWIG, M. BARTH, R. HENNICKER 2003: Web-based modelling of energy, water and matter fluxes to support decision making in mesoscale catchments-the integrative perspective of GLOWA-Danube. Physics and Chemistry of the Earth 28, Pages: REUDENBACH, C., G. HEINEMANN, E. HEUEL, J. BENDIX AND M. WINIGER, 2001: Investigation of summertime convective rainfall in Western Europe based on a synergy of remote sensing data and numerical models. Meteor. Atmosph. Phys. 76; REUDENBACH, C. 2003: Convective summer precipitation in Central Europe (in German). Bonner Geogr. Abh pp. Sankt Augustin. REUDENBACH, CH., T. NAUSS, & J. BENDIX 2004: Retrieving precipitation woth GOES, Meteosat and Terra/MSG at the tropics and midlatitudes. In: Levizzani, V., P. Bauer & F. J. Turk (edt.): Measuring precipitation form space. In press.