Remote sensing of cloud liquid water during ICE'89

The cloud liquid water path, LWP, over the North Sea during the International Cirrus Experiment 1989 (ICE'89) is derived from measurements of the microwave radiometer SSM/I on board.of the polar orbiting satellite DMSP and from measurements of a ground-based 33-GHz-radiometer operating on board of the German research vessel 'Poseldon'. Comparisons of maps of LWP compiled from the SSM/I data with time series computed from the ground-based system show no significant bias and agree within the range of uncertainty caused by the different sampling characteristics of the observing systems. Using a combination of SSM/I data and almost simultaneously recorded METEOSAT-IR data offers the possibility to identify different cloud types, e.g. to seperate cirrus clouds and cirrus with underlying water clouds. Both types may have the same IR-brightness temperature but different microwave brightness temperature because ice clouds have a negligible influence on the microwave radiances