4D-clouds general description

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The 4D-clouds project aims at capturing the radiative influence of inhomogeneous clouds and at implementing these influences in the modelling of transport and exchange processes in dynamical atmospheric models. Especially, the project wants to contribute to the major scientific questions around enhanced absorption, the relation between albedo and optical depth in satellite retrievals, and the relation between dynamical exchange processes and the 4D cloud structure.


The measurement component of this project will be executed together with the EU-project CLIWA-NET in the Baltex Bridge Campaign (BBC), to be held in the Netherlands around Cabauw in August and September 2001. It will encompass satellite and diverse ground based remote sensing measurements and simultaneous in situ measurements of the microphysical and radiative properties with three airplanes. In total 7 remote sensing stations equiped with lidar ceilometer, infrared-radiometer and microwave radiometer, will be scattered over a region of 100 by 100 km. Furthermore, 4D cloud fields will be measured at Cabauw by making scanning measurements with a microwave radiometer and a cloud radar. Latent and sensible heat fluxes will be measured on a 213 m high meteorological tower and various state of the art radiation measurements will be performed in Cabauw.

modelling radiative transfer

In the radiation modelling part of the project, three dimensional radiative transfer models in all relevant frequencies will be further improved and the results will be compared with the measured spectral radiative densities and fluxes at the ground and at cloud level. The models will be used to improve satellite retrievals and to derive parameterisations (including error estimates) for the radiative transfer modules of cloud resolving and non-cloud resolving models (LM, HRM and REMO).

dynamical modelling

The project will be concluded by a dynamical modelling component in which the influence of inhomogeneous clouds on the vertical transport will be studied in the coupled system of surface, vegetation, boundary layer and free atmosphere.

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Meteorological Institute
University of Bonn
Auf dem Hügel 20
53121 Bonn, Germany

Sekretariat: Pia Rosen, Tel.: +49 (0)228 73-5190, Fax: +49 (0)228 73-5188, e-mail: miub@uni-bonn.de
homepage: http://www.meteo.uni-bonn.de/Deutsch/Forschung/Gruppen/fernerk.html