中尺度WRF模式在西北西部地区低层风场模拟中的应用和检验

Application and Test of Lower Level Wind Field Simulation with Meso-scale Model WRF in Western Region of Northwest China

通过WRF模式对西北地区1、4月份风速的模拟,检验了大气数值模式的模拟性能和误差大小。结果表明,WRF模式在风场模拟上具有较好的性能,在地面加热较强、增温较快、风速较大的4月份模拟效果要好于强风频发但风速较4月份小的1月份;4月份10～70 m各高度上48 h内的平均相对误差在10%以下,相关系数>0.80,通过99%的置信度;1月份各高度48 h的平均相对误差在20%以内,但二者呈负相关,相关系数绝对值>0.30,通过99%的置信度;在选取的2个模拟时段内,在阵性大风出现的时段模拟值明显小于观测值。意味着风作为高层动量下传、低层地形和热力作用共同的产物,在西北地区植被稀疏、地形复杂的环境下,模式边界层的参数化是关键。

In this paper,the performance of WRF model is validated by simulating wind velocity in January and April over northwestern China,and the errors between simulated and observed values were investigated.Results show that WRF performance was better in April,when wind speed was big and steady,surface heating strong and temperature increasing faster,but in January wind speed was lower but gust frequently occurred.The relative error in 48 hours at different levels was under 10%,the correlation coefficient（above 0.8） between observed and simulated values was significant at 90% in April.In January,the mean value of relative error in 48 hours at different levels was in the range of 20%,and the absolute value of the correlation coefficient was more than 0.30 and significant at the 99% confidence level.During the two simulation durations,the simulated value was obviously smaller than observed value when wind speed was high.Due to wind dominated by higher level momentum transfer downwards,terrain and thermodynamic function of land surface,the PBL parameters scheme in model is crucial in simulation of wind,especially in northwest China,where vegetable is sparse and terrain complex.