Numerical Simulation of Orographic Enhancement of Rain with a Mesoscale Model

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  • a Laboratoire Associé de Météorologie Physique, Université de Clermont-Ferrand II, 63170 Aubiére, France
  • | b National Oceanic and Atmospheric Administration, Air Resources, Laboratory, GMCC, Boulder, CO 80303
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Abstract

Orographic precipitation enhancement associated with the feeder mechanism proposed by Bergeron has been simulated using a two dimensions model based upon primitive equations including detailed parameter microphysics. A case-by-case comparison is made between model results and each of 14 well-documented precipitation episodes in southern Wales. The model reproduces the observed strong dependence of the precipitation enhancement on the low-level wind speed, as well as the weak dependence on the upwind precipitation rate. Model results also demonstrate that a satisfactory treatment of orographically enhanced precipitation requires the linking of the dynamical, thermodynamical and microphysical processes.

Abstract

Orographic precipitation enhancement associated with the feeder mechanism proposed by Bergeron has been simulated using a two dimensions model based upon primitive equations including detailed parameter microphysics. A case-by-case comparison is made between model results and each of 14 well-documented precipitation episodes in southern Wales. The model reproduces the observed strong dependence of the precipitation enhancement on the low-level wind speed, as well as the weak dependence on the upwind precipitation rate. Model results also demonstrate that a satisfactory treatment of orographically enhanced precipitation requires the linking of the dynamical, thermodynamical and microphysical processes.

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