Cloud thermodynamic phase from POLDER/ADEOS: comparison with millimeter wave radar measurements and synoptic weather reports

A method for cloud top thermodynamical phase determination has been developed, using polarimetric data from the spaceborne instrument POLDER. Eight months of data, corresponding to the POLDER/ADEOS operational period, have now been processed. In our present studies, two complementary approaches were developed to evaluate the accuracy of the cloud phase retrieval algorithm. At the global scale, the POLDER phase information is compared to ground based synoptic weather reports from the Extended Edited Synoptic Cloud Report. This database allows one to select observations of various cloudiness situations (cloud amount and types, multilayer clouds, thin cirrus), which are then compared with matching POLDER observations. The second approach consists in analyzing data from the Millimeter Wave Cloud Radar (Souther Great Plain -- ARM site) which are available for nearly the entire operational POLDER period. The sampling capabilities of the radar (data are acquired every 10 seconds) allows one to compare POLDER cloud top phase with cloud top pressure and temperature, derived from the MMCR data combined with radiosounding measurements. Both approaches show the consistency of the POLDER phase product but also lead to interesting results concerning the cloud phase problem.