“…[3] Despite the use of these products in a broad range of studies, from climate model validation to cloud-radiation interaction [e.g., Stephens and Greenwald, 1991;Zuidema and Hartmann, 1995;Chen and Roeckner, 1997;Borg and Bennartz, 2007;Ming et al, 2007], little is known regarding their error characteristics. Direct comparisons against in situ and surface-based microwave observations have yielded promising results for limited cases [Greenwald et al, 1993;Cober et al, 1996;Prigent et al, 1997;Offiler et al, 1998]; however, aircraft measurements have sample size and representativeness issues, as well as being relatively rare and costly; whereas observations from surface-based microwave radiometers can exhibit significant systematic errors [Turner et al, 2007].…”