黑河流域土壤参数修正及其对大气要素模拟的影响

Modification of the Soil Characteristic Parameters in Heihe River Basin and Effects on Simulated Atmospheric Elements

根据Cosby等1984年总结的土壤特征参数计算方法和基于黑河流域53个土壤剖面数据,得到对应于美国农业土壤分类标准的黑河流域6类土壤的平均粘、砂含量,计算了黑河流域各类土壤的特征参数,分别采用Cosby等计算的土壤参数以及黑河土壤剖面数据计算的土壤参数,运用耦合了NOAH陆面过程模型的大气中尺度模式(Mesoscale Model version 5,MM5)模拟土壤参数变化对黑河流域中上游大气要素模拟的影响。结果显示:b参数和饱和导水率改变对局地能量变化影响很大,饱和土壤水势以及孔隙度对局地水分传输变化影响较大。特征参数变化引起的温度场变化位于砂质土壤和粉壤土覆盖范围,而湿度相关要素场变化则主要位于中游绿洲粉壤土、粉土覆盖区。通过与观测值的比较发现,除阿拉善右旗外,使用Heihe数组土壤参数后模拟的气温、湿度及风场都有一定改进。

The sand-clay percentage was obtained at maintype lever corresponding to USDA classification based on 53 soil sample data collected in Heihe river basin.The soil characteristic parameters were gotten in Heihe river basin using the method described by Cosby（1984）.The two datasets of Cosby and Heihe parameters were used in MM5 model coupled with Noah land surface model to simulate the effects on atmospheric fields.The following conclusions were obtained that： The retention curve and saturated hydraulic conductivity changes lead to temperature fields change in larger extents than others.While,porosity and saturated metric potential affect humidity fields larger than other parameters.The main difference concerning temperature locates at regions covered with sandy and silt loam soil.The main difference concerning water vapor exchange locates at oases covered by silt loam or silt soil.Simulation results were compared with observations.It is obtained that the simulated air temperature,specific humidity and wind fields were closer to observation using Heihe data than Cosby data.