土地利用类型变化对城市大气边界层特征影响的数值模拟

利用ENVI和IDL,GIS以及上海市航片,将ARW-WRF中尺度模式中的下垫面土地利用类型数据中上海市部分做了修正:对照模式中24种土地类型分类,将原本定义为农作物耕地和草场,草地,灌木丛,以及沙土和淤泥的部分,根据实际情况改为城区和在建城区,扩大了城市的范围,获取城市建筑物高度信息以得到更精确地粗糙度数据,使其与实...

Numerical simulations of effects on urban PBL characters with landuse categeories modification

ENVI, IDL, GIS and aerial photographs were used to modify landuse data in ARW-WRF within Shanghai area. Firstly, grids were gained with GIS into the same resolution with the input data in WRF, which is too old for present landuse situation in Shanghai. Secondly, irrigated cropland and pasture, grassland, shrubland, loamy sand and silt were partly changed into urban and built-up land grid by grid, so as to be more closer to real situation, and the distribution of buildings was gained, helping to reach more accurate roughness value in UCM according to the 24 landuse categories defined in WRF model. Lastly, both modified and original data were input into WRF in case simulations. The wind field, temperature, and other characters of PBL in spring of Shanghai were gained in the simulation results. It shows that because of landuse types modification, horizontal wind velocity decreases obviously, displaying the urban dragging effects. Meanwhile, the vertical wind velocity increases, being greatly affected by surface warming effects. The higher temperature centers appear in the downwind direction by the effects of surface wind fields. Surface temperature and PBL height are both closer to observation values. The results lead us to discuss the importance of landuse categories input in models, and some other possible reasons causing the difference were mentioned.