Numerical Simulation of a Subtropical Squall Line over the Taiwan Strait

Abstract A two-dimensional, time-dependent, and nonhydrostatic numerical cloud model is used to study the development and structure of a subtropical squall line that occurred during TAMEX (Taiwan Area Mesoscale Experiment). The model includes a parameterized ice-phase microphysical scheme and long- and shortwave radiative transfer processes, as well as heat and moisture fluxes from the ocean surface. It was found that dynamic and kinematic structures of this simulated subtropical squall line are quite similar to its counterparts observed in the tropics and midlatitudes. For example, the squall line has a quasi-steady structure with a successive generation of cells at the gust front that propagate rearward relative to the front, the precipitation, and an evaporatively cooled downdraft at low and midlevels. This particular subtropical squall line is also shown to have a distinct midtropospheric rear inflow and a moderate anvil component of the total precipitation. The vertical transport of horizontal moment...