Partitioning of cloud water and rainwater content by ground-based observations with the Advanced Microwave Radiometer for Rain Identification (ADMIRARI) in synergy with a micro rain radar

Cloud and rain liquid water path and total water vapor are retrieved simultaneously from passive microwave observations with the multifrequency dual-polarized Advanced Microwave Radiometer for Rain Identification (ADMIRARI). A data set of linearly polarized brightness temperatures has been collected at 30 elevation angle together with slant radar reflectivity profiles at 24.1 GHz from a micro rain radar (MRR) pointing into the same viewing direction. The slant path integrated values are retrieved via a Bayesian inversion approach, the quality of which is evaluated by a simulation-based retrieval sensitivity study. The algorithm includes a physical constraint by taking into account the rain column structural information from the MRR observations. Measurements and derived path-integrated water component estimates from 23 August to 12 November 2008, obtained in Cabauw, Netherlands, are analyzed. During raining cloud conditions the zenith-normalized root-mean-square error for water vapor, cloud liquid water path, and rain liquid water path are, on average, estimated to 1.54 kg m-2, 144 g m-2, and 52 g m-2, respectively. On the basis of these results, long-term estimated distributions of cloud water-rainwater partitioning for midlatitude precipitating clouds are presented for the first time as obtained by a ground-based radiometer. Copyright 2012 by the American Geophysical Union.