WRF模式对中国夏季降水的动力降尺度模拟研究

采用NCEP的FNL再分析资料驱动WRF模式,对中国10 a(2000—2009年)夏季降水进行双重动力降尺度(双重嵌套)模拟,将子、母区域模拟结果和观测进行对比,以检验双重动力降尺度对中国夏季降水模拟的"增值"能力。结果表明:单重动力降尺度(单重嵌套)方法能较好模拟出中国10 a夏季平均降水的空间分布,对季风雨带"北跳"特征模拟较好,但模拟降水具有系统性正偏差。在母区域的强迫下,双重动力降尺度模拟的降水分布与单重动力降尺度相比,没有发生根本性变化。但由于子区域的分辨率要高于母区域,双重动力降尺度比单重动力降尺度能提供更多有价值的降水细节。双重动力降尺度的这种"增值"能力存在地域依赖性,在华南地区和江淮地区,双重动力降尺度模拟出的降水分布、量值和逐日演变都要好于单重动力降尺度。但在华北地区,双重动力降尺度没有表现出明显的"增值"。

Double nested dynamical downscaling research on summer precipitation over China with WRF model

A 10-year(2000-2009) double dynamical downscaling(couble nested) simulation on summer precipitation in China was conducted by Weather Research and Forecasting WRF model driven by FNL reanalysis data from NCEP. The added value of summer precipitation simulation by double dynamical downscaling method is investigated through comparing the mother domain and subdomain outputs with the observation. Results show that single dynamical downscaling simulation can quite well simulate the spatial distribution of 10-year average summer precipitation and the evolution of rain belts of summer monsoon, but it has systematic wet bias in precipitation simulation. Under the force of mother domain, the precipitation distribution by double dynamical downscaling is similar to that by single dynamical downscaling. However, the double dynamical downscaling method can provide more valuable precipitation details because of the higher spatial resolution of the sub-domain. The result of added value by double dynamical downscaling is regionally dependent. The amount, distribution and daily evolution of precipitation by double dynamical downscaling can be simulated better than those simulated by single dynamical downscaling over South China and Yangtse-Huaihe River which are characterized by complex topography, but no obvious added value was found over North China.