关键词: 沙尘暴, 中低压, 数值模拟

Abstract:

Using PSU/NCAR mesoscale numerical model(MM4 standard model), taking 40 km horizontal grid spacing, 46 latitude and 61 longtitude dot grid points, and 15 vertical sigma levels with δ=0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.78, 0.84, 0.89, 0.93, 0.96, 0.98, 0.99 and 1.0, from model top(100hpa) to it's bottom, we simulated successfully the evolution and distribution of the duststorm process' sea-level pressure system, especially three middle-lower pressures in Zhangye, Qaidam basin and near Dunghuang through using MCAR 30×30 topographic data and regular observatoinal data as initial fields. Simultaneously, we simulated Guansu Hexi duststorm pressure. Sensitivity test demonstrated that duststorm's formation and development is mainly constrained by dry physical process. The research of duststorm mesoscale systems is different from that of rainstorm mesoscale systems, so that cumulus parameterization is not especially important. Attention should be paid to deal with other factors, dynamic process and functions exerted by atmospheric exteral force in duststorm numerical model design and research. The moded's horizontal grid spacing and topographic truth contribute greatly to middle - lower pressure position and central intensity simulation. The change of undrelying surface has a certain effect on middle -lower pressure. Under the favourable circulation situation, the formation and development of thermal lowerpressure in Zhangye, especially topographic structure play an important role in immediate dynamic forcing.

Key words: Sand and dust storm, Middle-lower pressure, Numerical simulation