MM5 model has the main functions of non static dynamic frame, multi-layer grid nesting, various physical process options, four-dimensional variation, and more extensive computer platform transplantation. The simulation area of MM5 adopts Lambert projection, and the two true latitudes are 25 degrees north latitude and 40 degrees north latitude respectively. In order to ensure the accuracy of boundary meteorological field, MM5 simulation area has three grids more than the horizontal boundaries of air quality simulation area; the top of the simulation layer is 100MB, which is vertically divided into the following 23 σ layers. The data of terrain and surface type are global data of USGS; the objective analysis is based on the ADP global surface and high-altitude observation data of NCEP to conduct grid four-dimensional data assimilation. The parameterization of physical processes in the simulation domain are as follows: Kain Fritsch's cumulus parameterization scheme; pleim Xu's boundary layer and land surface parameterization scheme; Reisner's multiphase explicit water vapor scheme; cloud radiation parameterization method; and multi-layer soil model.
