10.2 Precipitation characteristics from trade wind clouds during RICO derived from radar, satellite and aircraft measurements

Thursday, 13 July 2006: 10:45 AM
Ballroom AD (Monona Terrace Community and Convention Center)
Eric R. Snodgrass, Univ. of Illinois, Urbana, IL; and L. Di Girolamo, R. Rauber, and G. Zhao

Twelve times during the RICO (Rain In Cumulus over the Ocean) field campaign, MISR (Multiangle Imaging SpectroRadiometer) onboard the EOS Terra Spacecraft and NCAR's S-POLKa radar collected coincident high-resolution visible and near-IR satellite data and dual-polarization S-band radar reflectivity data to understand trade wind cumuli cloud distribution and precipitation. Using a Z-R relationship derived from optical array probe data from the NCAR C-130, rainfall characteristics of these clouds were examined by collocating the radar reflectivity and rain-rate with the satellite reflectance at the pixel level.

Collocating these data has offered a unique perspective into the macrophysical characteristics of trade wind clouds and this presentation will focus on the role these clouds play in the water cycle of the trade wind regime in the Western Tropical Atlantic. First, through a latent heat flux analysis, it was found that these clouds are between 11-15% efficient at returning evaporated water to the ocean through precipitation. Furthermore, only 7% of the cloudy area observed by MISR was responsible for this rainfall and it will be shown that the mesoscale organization of this shallow convection holds a strong correlation with precipitation intensity and distribution. Also, to demonstrate the representativeness of these twelve coincident scenes, rainfall statistics from the entire field campaign (66 days) will be presented which will show the diurnal cycle in precipitation and define the rainfall characteristics observed during RICO. Finally, the potential application of these results for cloud resolving models and large eddy simulations will be discussed.

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