3D cloud products for weather prediction and climate modelling

[摘要] In this paper, the possibilities of satellite-based andground-based stereoscopy of clouds are examined,with the objective to derive cloud top and cloud baseheights and motion. These parameters are very important for a better description of clouds for nowcastingand numerical weather prediction models. For the satellite part, images of ATSR2 (on ERS-2) and MISR(on EOS Terra) are used. As stereo image pairs frompolar-orbiting satellites are never perfectly synchronous(time delay of some seconds between the imagereeeption from the different viewing angles), the heighterror of the cloud top heights, introduced by thealong-track motion component, is corrected with thecloud top winds extracted from Meteosat-6 and -7.For MISR, with nine viewing angles, this height correction is not needed when at least three images fromnon-symmetric cameras are used; then, it is possibleto directly separate the along-track parallax (due tocloud height) from the along-track wind contribution(due to cloud motion). Our new ground-based imagerSystem was operated in eoineidence with an overpassof ERS-2 in October 1999. The ground measurementsproved to be an interesting technique to validate satellite-based cloud top height and motion of verticallythin clouds and to additionally detect more detailedcloud features, which is particularly important for aecuratenoweasting in mountainous terrain.

[学科分类] 自然科学（综合）