7.5 Dominica's Downslope Winds: Morphology & Dynamics of a Plunging Downslope Flow in the Tropics

Wednesday, 7 August 2013: 11:30 AM
Multnomah (DoubleTree by Hilton Portland)
Justin R. Minder, University at Albany, Albany, NY; and R. B. Smith

Many studies have investigated the morphology and dynamics of strong topographically enhanced downslope winds in the mid-latitudes. However, downslope winds in the Tropics have received minimal attention. A combination of factors may make tropical downslope winds distinct. These include: conditionally unstable stratification, very moist air, trade wind inversions, and frequent flow reversals aloft.

We use the mountainous Caribbean island of Dominica to investigate the downslope winds that occur in a moist, convecting, trade wind flow. Airborne in-situ and dual-Doppler cloud radar measurements taken during the DOMEX-2011 field campaign are used to characterize the plunging, turbulent, warm, and dry flow that often occurs over Dominica's lee slopes. This flow bears many similarities to mid-latitude downslope winds and hydraulic analogs, despite the presence of vigorous moist convection and substantial latent heat release over the windward slopes. High-resolution numerical simulations with the WRF model are used to determine how various environmental conditions (incoming flow speed, inversion structure, mean-state critical layers) and processes (latent heating, moist convection) control the strength and structure of Dominica's downslope winds.

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