Simultaneous estimates of cloud and rainfall parameters in the atmospheric vertical column above the Atmospheric Radiation easurement Program southern Great Plains site

Abstract

A novel remote sensing approach to simultaneously retrieve cloud liquid water paths (LWP) and ice water paths (IWP) and mean rainfall rate in a vertical atmospheric column was applied for stratiform-like precipitation events observed during the warm period of 2007 at the southern Great Plains site of the Atmospheric Radiation Measurement (ARM) Program. The retrieval method is based on multifrequency radar measurements at W, Ka, and S bands and raindrop size distribution estimates from a ground-based impact disdrometer. The radar measurements also provide a robust separation of the liquid, ixed, and ice hydrometeor layers. Characteristic values of LWP are about 300-400 g m -2, although values up to 1000 g m -2, and higher are not uncommon. There is on average insignificant correlation between cloud LWP and rainfall rates. IWP, which represents the precipitating cloud part of the atmospheric column that is observed above the freezing level, usually significantly exceeds cloud LWP in the liquid hydrometeor layer and can reach values of approximately 10 4, g m -2, and even higher. On average, mean rainfall in the liquid layer, R m increases with an increase in ice mass observed above the melting layer, although a corresponding mean correlation coefficient between R m and IWP is only 0.32. There is noticeable variability in IWP-R m relations between individual events. Storm dynamics is likely to influence the correlation between cloud and rainfall parameters as inferred from simultaneous columnar retrievals. Initial estimates indicate that IWP and rainfall are stronger related for events which exhibit lower vertical variability of wind. Copyright 2009 by the American Geophysical Union.