Numerical Simulation of Mesoscale Eddies over Melbourne

Abstract

A mesoscale wind field model is used to simulate a cyclonic nocturnal eddy which may form over Melbourne under stable conditions with light synoptic winds. Two types of eddy (Mel-I and Mel-II) are identified, with separate formation mechanisms. Mel-I is generated by vorticity shed from the upstream mountain ranges. Daytime anabatic effects enhance the strength of the eddy. When surface heat fluxes are suppressed, the numerical simulations are found to parallel previous to laboratory experiments, but with a somewhat relaxed Froude number formation criterion. The second type of eddy, Mel-II, is generated by interaction of the sea breeze front with the synoptic flow. The eddies are compared with the Kanto plain eddy modeled by Kimura.