土地利用城市化对珠三角炎热天气的影响

Impact of land use changes after urbanization on meso-scale simulation of a hot episode in Pearl River Delta

土地利用类型的变化对MM5模拟结果的准确性有着重要的影响。不同的土地利用类型,有着不同的地表粗糙度,反照率,热容量,有效湿度等,从而产生不同的模拟地面热通量及地面水汽通量,并通过垂直方向的湍流输送,影响到高空气象场的模拟结果。利用2001年卫星遥感土地类型等数据,对MM5系统旧的24类全球土地利用数据在珠三角区域进行了更新;通过把珠三角地区的土地利用设为常绿阔叶林和城市两种不同类型的敏感性模拟测试,可以看到土地利用的变化,对温度、风场等气象场的模拟结果影响较大;通过1993年和2001年土地利用情况下的模拟气象场及与观测数据的对比分析可以知道,采用新的土地利用类型可以较好地改进MM5气象场模拟结果的准确性,土地利用的城市化趋势会造成城市密集地区地表温度升高,水汽混合率降低。

The land use pattern has significant influence on the accuracy of MM5 simulation results.Different land use patterns,with different surface roughness,albedo,heat capacity and effective humidity,result in different simulated surface heat and vapor fluxes and would in turn affect the simulation results of meteorological fields of upper atmosphere through vertical turbulent transport.Using the satellite remote sensing data in 2001,the old global 24-category land use pattern in the Pearl River Delta region in the MM5 system was updated.In the sensitivity test,the land use pattern in the Pearl River Delta region was set to a broadleaved evergreen forest and an urban area separately,and the simulated temperature,wind and other meteorological fields in the two cases were very different.The differences between the simulated meteorological fields using the land use pattern in 1993 and 2001 were analyzed and compared with observation data.It is found that the land use pattern in 2001 can greatly improve the accuracy of MM5 simulation results and the urban land use pattern causes the near-surface temperature to increase and vapor mixing ratio to decrease in the urban region.