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Synergetic use of Radar and optical Satellite Images to Support Severe Storm Prediction

Stephan Brusch(1), Susanne Lehner(1) and Johannes Schulz-Stellenfleth(1)

(1) DLR, M√ľnchnerstr. 20, 82234, Germany

Abstract

In this study we show how satellite images taken by space-borne radar sensors can be used to determine mesoscale high resolution wind. A severe weather event happened in early November 2006 over the North Sea, that damaged the measurement platform FiNO 1. This case of a particularly intense cold air outbreak over the North Sea in early November 2006 is investigated using satellite data. Atmospheric boundary layer rolls and open cell convection was observed by the Advanced Synthetic Aperture Radar (ASAR) and the Medium Resolution Imaging Spectrometer (MERIS) instrument, sensors on board the ENVISAT satellite. The aim of this study is to use SARs in synergy with MERIS data to analyse severe weather systems, in particular to describe the spatial evolution of the atmospheric boundary layer processes involved in cold air outbreaks. Cloud patterns parallel as well as perpendicular to mean wind direction that amount the cell structure of about 10 km diameter were observed. Similar patterns were observed in SAR images. These are believed to be surface effects of gust fronts induced by the mesoscale cellular convection and enhanced by the overall northwesterly flow. This is explained by downward transport of higher momentum in convective clouds. Meteosat Second Generation (MSG) is used to determine the movement of these patterns. Cloud patterns seen in the optical data and radar cross section modulations give a consistent dynamical picture of the atmospheric processes. The satellite data are used to validate numerical model results (LSM, HIRLAM) are presented. The focus of this research is on the impact of high variability in wind speed of mesoscale convective cloud patterns, which are not well captured by these numerical models. The macroscale and mesoscale wind field features are described on separated scales.

 

Workshop presentation

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry