Role of a Parameterized Ice-Phase Microphysics in an Axisymmetric, Nonhydrostatic Tropical Cyclone Model

Abstract

Results of an axisymmetric, nonhydrostatic hurricane model are analyzed with emphasis on the role of a parameterized ice-phase microphysics Inclusion of ice processes produces dramatic differences in the structure and evolution of the simulated hurricane vortex. Mesoscale convective features are wore plentiful with ice, and the simulated vortex grows more slowly. Time and space-averaged budgets of key model varibles show that cooling due to melting ice particles can initiate and maintain model downdrafts on a horizontal scale of tens of kilometers. This scale depends critically on both the horizontal advection of the parameterized snow particles detrained from the tops of convective updrafts and the mean fall speed of the particles toward the melting level. In situ0 production of snow particles results from a wide variety of parameterized microphysical processes and is significant factor in maintaining upper-level snow concentration These processes are strongly height-dependent.