Investigations of cloud layer base and top heights from 95 GHz radar reflectivity data

Cloud radars operating at millimeter wavelengths have proven to be invaluab le for studying the S-dimensional distribution of stratiform clouds. An imp roved knowledge of the occurrence of multiple cloud layers as well as of he ights of their upper and lower boundaries is important for the determinatio n of radiative fluxes with a higher accuracy. In this study measurements wi th the 95 GHz radar of GKSS Research Centre, Geesthacht, are used to determ ine base and top heights of layers of different cloud types. However, an ac curate retrieval of cloud boundaries by remote sensors is not obvious, e.g. , it is known that simultaneous measurements of the radar and backscatter l idars often show significant differences in cloud base heights. Reasons for inaccuracies in the determination of cloud boundary heights are discussed. Possibilities for corrections are illustrated that will finally lead to mo re reliable cloud boundary statistics necessary to improve radiative transf er calculations within large-scale weather forecasting and climate models. (C) 1999 Elsevier Science Ltd. All rights reserved.