Jennifer Davison, Graduate Student

The Rain In Cumulus over the Ocean (RICO) experiment occurred during winter 2004/2005 with operations based on the islands of Antigua and Barbuda.  The over-riding purpose of RICO was to determine the mechanisms which contribute to the initiation and the longevity of the trade wind fair weather cumuli.  Traditionally in the tropics, soundings have served as the basis for characterizing the ambient environment.  However, unique sounding sampling strategies during RICO revealed very high moisture variability, which calls into question our current understanding of tropical dynamics.

 In an effort to spatially and temporally augment the sounding characterization of the environmental moisture profile, use can be made of SPOLk-a radar data.  A technique utilizing clear-air Bragg scatter returns from PPI scans of S-band radar was developed to locate local maxima and minima in the mean relative humidity vertical profile.  Although coarse, these measurements reflect the mesoscale average of what is largely small scale moisture variability.   While no information is retrieved as to the magnitude of each RH maxima and minima detected, these measurements combined with sounding data have the potential to significantly impact our understanding of many atmospheric phenomena – including insights into the workings of the tropical boundary layer.  Currently a new conceptual model of the tropics is being developed which not only affects tropical dynamics, but could also have a significant impact on our understanding of the radiation, water, and energy budgets of the tropics.