Initialization of a Cloud-Resolving Model with Airborne Doppler Radar Observations of an Oceanic Tropical Convective System

Abstract

Doppler radar?derived fields of wind and reflectivity, retrieved temperature perturbations, estimated water vapor, and cloud water contents are used to initialize a nonhydrostatic cloud-resolving model. Airborne Doppler data collected in a tropical mesoscale convective system on 9 February 1993 during the Tropical Ocean Global Atmosphere Coupled Ocean?Atmosphere Response Experiment are prepared for this purpose. Different numerical experiments are conducted to verify the reliability of the approach and to determine the most important parameters leading to the most realistic simulations possible. The obtained results show that the numerical model can be initialized with two-dimensional wind and reflectivity fields describing a well-developed convective circulation. A major conclusion is that, apart from the horizontal and vertical wind, the most important parameter in the initial field is humidity. Although a relatively crude thermodynamic and microphysical description was sufficient, a complete description of the saturated/unsaturated conditions is essential to obtain simulations matching the observed characteristics. Finally, consequences of the results for the understanding of the 9 February 1993 mesoscale convective system and future applications of this technique are discussed.