The Environment of Precipitating Shallow Cumulus Convection

Louise Nuijens, Bjorn Stevens, A. Pier Siebesma
2009 Journal of the Atmospheric Sciences  
Quantitative estimates of precipitation in a typical undisturbed trade-wind region are derived from two months of radar reflectivity data and compared to the meteorological environment determined from soundings, surface-flux, and airborne-lidar data. Shallow precipitation was ubiquitous, covering on average about two percent of the region and contributing to at least half of the total precipitation. Echo fractions on the scale of the radar domain range between zero to ten percent and vary
more » ... y within a period of a few hours to a day. Variability in precipitation relates most strongly to variability in humidity and the zonal wind speed, although greater inversion heights and deeper clouds are also evident at times of more rain. Our analysis suggests that subtle fluctuations in both the strength of the easterlies and in subsidence play a major role in regulating humidity, hence precipitation, even within a given meteorological regime, here the undisturbed trades.
doi:10.1175/2008jas2841.1 fatcat:rl4g4b5g3vblfoe4fifbxze5ie