Radar based re-conceptualization of the Tropical Marine Boundary Layer (TMBL)

 Jennifer Davison, University of Illinois

Bragg scattering layers (BSLs)were commonly observed in cloud free regions of the western Atlantic TMBL during the Rain in Cumulus over the Ocean (RICO) field campaign with the NCAR S-Pol radar. An algorithm based on the Haar wavelet was developed to derive the altitudes of the base and top of each BSL. Using this derived data, it can be shown that BSLs are a persistent, coherent feature of the TMBL that delineate aspects of its mesoscale structure. Furthermore, BSLs exist in layers with tops defined by local relative humidity (RH) minima and bases defined by local RH maxima. Possible mechanisms for the formation and maintenance of BSLs include turbulence, cloud detrainment, and large scale subsidence. Statistical analyses were compiled and used to create a revised conceptual model of the TMBL that incorporates multiple moist and dry layers and a higher TMBL top. The model is validated by comparing BSL tops with satellite-derived cloud tops. A point that comes out of this work is that soundings are inadequate to characterize the highly variable moisture field in this environment. Given that BSLs have been detected by S-Pol at DYNAMO, this work may have a direct bearing how results from this campaign are interpreted.

Tuesday, 6 March 2012, 10:30 AM

Refreshments 10:15 AM

NCAR-Foothills Laboratory

3450 Mitchell Lane

Bldg 2 Auditorium (Rm1022)

Will this event be webcast to the public by NCAR|UCAR?: 
Announcement Timing: 
February 23, 2012 to March 6, 2012