MM5模拟垂直风剖面的准确性探讨及在垂向气象场的分析应用

Improvement Test for Simulation of Vertical Wind Profile in MM5 and Simulation Analysis of Meteorological Fields in Vertical Cross-Section

通过调整垂直方向的垂直层分布及增加垂直层数,提高MM5对近地面及中高空风、温度等气象场的模拟准确度,更好地模拟垂直风剖面随高度的变化。特别地,由于模式中2 000 m以上中高空的垂直层比较稀疏,加密垂直层能比较显著改善中高空气象场的模拟结果,这对于研究对我国影响较大的西南风低空急流和高空急流等气象现象有较重要的意义。讨论研究了土地利用的更新对垂直风剖面造成的影响,对比分析了新旧土地利用类型下珠江口三个垂直剖面的流场变化。土地利用的更新会产生不同的地面热通量和水汽通量,并通过垂直方向上的湍流输送进一步影响到高空气象场,从而改善垂直风剖面数值模拟的准确度。

By adjusting the, distribution of vertical sigma levels and increasing its number, the accuracy of computed wind, temperature and other meteorological fields are improved in near surface and upper levels in MM5 simulations. In particular, the density of vertical levels above 2000 meters is usually sparse compared with that near surface levels. Increasing the number of vertical levels above 2000 meters Can improve greatly the accuracy of computed meteorological fields in upper levels, resulting in better analysis of weather phenomena such as the southwest low-level and high-level jets which have significant influence in the South China region in summer. The changes of vertical wind profile caused by updating of land use pattern are studied. The streamline fields are compared and analyzed in three vertical crosssections in the Pearl River estuary. The updating land use patterns would lead to more realistic surface heat and vapor fluxes, resuhing in more accurate upper atmosphere meteorological fields, such as the ver- tical wind profile, through vertical turbulent transport.