A new look at - Tropical Middle-Troposphere Clouds

Zuidema, Paquita	RSMAS/MPO University of Miami
Mapes, Brian	University of Miami
Lin, Jialin	NOAA-CIRES Climate Diagnostics Center
Fairall, Chris	NOAA/Environmental Technology Laboratory

Direct observations are made of the cloud vertical structure within the tropical convective atmosphere using cloud radar measurements from two ship-based tropical observational campaigns. These are interpreted with soundings, large-scale divergences calculated from precipitation radar Doppler velocities, and surface rainfall rates. A remarkable consistency exists between the large-scale divergences calculated from the precipitation radar doppler velocities, and the cloud structure perceived by the vertically-pointing cloud radar. These indicate very different dynamics for the convective environment of each campaign. One campaign, the Eastern Pacific Investigation of Climate, documented mid-troposphere layers of low relative humidity (RH < 40%) occurring within otherwise moist environments. The dry layers, centered at ~ 7km, are thought to originate from near the equator and to represent a climatological feature. The cloud vertical structure provides evidence of not only the suppression of surface-based convection but also of the sublimation of cirrus anvil ice by dry layers below; the latter is a microphysical feature that has received little previous documentation. In contrast, mid-troposphere relative humidities during the Joint Air-Sea Monsoon Interaction Experiment rarely fell below 60%, once the monsoon onset had begun. The cloud vertical structure during JASMINE includes more melting-level outflow than EPIC, upper-level (~ 12 km) cirrus previous to the monsoon onset advected in by an easterly jet, and an example of an unusual double-convective cell. These results have relevance for the TWP-ICE experiment, and demonstrate the strength of combining dual cloud and precipitation radar observations.

This poster will be displayed at the ARM Science Team Meeting.