黑河地区行星边界层平均结构演变的三维数值模拟

THREE-DIMENSION NUMERICAL SIMULATION OF EVOLUTION FOR THE MEAN STRUCTURE OF THE PBL IN HEIHE REGION

本文利用一个改进和发展的高分辨三维中尺度数值模式,用FGGEⅢb资料对具有复杂下垫面和地形的黑河地区晴天边界层演变进行了模拟。结果表明,该模式具有模拟该地区夏季边界层平均结构及其演变的能力。模拟的地面诸通量演变与一些观测分析结果基本一致,但因下垫面的不同会有某些差异,对晴天边界层平均结构演变的18小时模拟能明显地区分白天和夜间的不同特征。白天混合层是在08时(北京时)以后逐渐发展建立的,在大约16时增长到其最大厚度1.5km;该混合层可持续到21时。夜间稳定边界层在大约22时建立。但无论白天或夜间,下垫面的非均匀性对边界层平均结构及其演变均有明显的影响。

An improved and developed high-resolution three dimensional mesoscale numerical model is used to simulate evolution of clear planetary boundary layer(PBL) in Heihe region with complex underlying surfaces and terrain, by using the data of FGGEⅢb in July 1979. The simulated results show that this model is capable for simulating mean structure and its evolution in the PBL in this region during Summer. The evolution of simulated surface fluxes is basically in agreement with some results of observational analyses, however, there are some differences because of different underlying surface. The 18 hours simulation for the evolution of the mean structure in the clear PBL is able to distinguish obviously different features between daytime and nocturnal. A mixed layer (ML) is progressively developed and built up after 8 BLT during the daytime, which reaches its maximum depth 1.5 km about 16 BLT, this mixed layer may be persisted until 21 BLT. A stable boundary layer during nocturnal is built up about 22 BLT. However, either daytime or nocturnal, the mean structure: and its evolution for the PBL are obviously affected by the inhomogeneity of the underlying surface.