Seminar Ozean, Eis, Atmosphäre

Date: 27.05.2003

Speaker:S. Crewell
Meteorological Institute, University of Bonn, Bonn, Gemany

The BALTEX BRIDGE campaign (BBC) was performed in response to the need for a better understanding of cloud processes as these are the major contributors to the uncertainty in climate and numerical weather forecast models due to their inhomogeneous structures and their complex interactions with radiation. In order to tackle these problems we designed an integrated approach combining state-of-the-art ground-based, aircraft and satellite measurements with accompanying atmospheric model activities. The campaign took place in August/September 2001 in the Netherlands with a central facility hosting advanced remote sensing instrumentation (Cabauw) surrounded by a regional network in a 100 by 100 km2 domain. Special focus was put on the observation of the cloud liquid water content as this is the prognostic parameter used to treat clouds in atmospheric models and linking atmospheric dynamics to radiation. The synergy of ground-based microwave radiometer, cloud radar, lidar and auxillary measurements at Cabauw was used to derive the vertical structure of clouds in high temporal resolution. The spatial characteristics of the cloud fields were investigated using satellite and aircraft data. The performance of four operational atmospheric models was evaluated and revealed large discrepancies in the forecasted liquid water paths between the different models and observations.