Numerical Simulation Study for the Structure and Evolution of Tropical Squall Line
热带飑线结构和演变的数值模拟研究第一部分：云分辨模式

The occurrence and evolution of an oceanic tropical squall line observed on 22 February 1993 during TOGA-COARE over the equatorial Pacific Ocean were simulated by use of a three-dimensional,nonhydrostatic storm-scale numerical model ARPS. The capacity of ARPS to simulate such tropical squall line was verified. The structure and dynamic mechanism of the squall line were discussed in details as well.The impacts of the different microphysical process that including the ice phase and warm rain schemes on structure and evolution of the squall line were investigated by the sensitive experiment.The simulations of the three-dimensional structure and evolution of the squall line are closely related with the observations when the proper microphysical processes were employed. The more latent heating released in the ice phase processes associated with the freezing process leads to strengthening deep convection due to the vertical gradient of buoyancy, which results in a long life of the convective system. In contrast, the warm rain process is characterized by short life period, more pronounced rearward tilt structure and extension of stratiform cloud.