RSM模式对中国东部夏季降水模拟能力的检验

本文利用美国国家环境预报中心NCEP(National Centers for Environmental Prediction)区域谱模式RSM(Regional Spectral Model)对中国东部地区夏季降水进行了为期20 a(1984—2003年)、水平分辨率为30 km的高精度模拟,并对模拟所得降水的气候态、年际变率、逐日变化以及极端事件进行了检验,和对造成降水偏差的大气环流特征进行了分析。结果表明RSM模拟所得夏季降水的空间分布、时间变率,以及降水量值都与实况相近,也基本可以再现夏季降水的年际变率分布情况,但是模拟所得的雨带存在偏南且偏弱的特点。对于逐日降水特征,RSM模拟所得季节内逐日降水变化与实况的走势基本一致,再现了夏季降水主要集中于东部和南部的特点,模拟出了江淮地区6月日降水区随时间北抬的特点。对于极端事件,模拟和实测的夏季不同雨强的天数分布对比表明模拟与实况基本接近,但是模拟的降水日大值中心较实况偏北;极端降水指数的计算结果也表明RSM模拟的极端降水情况与实况基本一致。综上,RSM模式对中国东部地区降水有着较好的模拟能力,可以用于中国东部地区的夏季降水气候特征研究。

Simulation on summer monsoon precipitation over eastern China by using regional spectral model

The National Centers for Environmental Prediction (NCEP) Regional Spectral Model (RSM) was used to simulate 20-year (1984-2003) summer precipitation over East China with high horizontal resolution of 30 km, moreover, the climatology, interannual variability, daily variation and extreme events found from simulation was tested and the atmospheric circulation characteristics causing precipitation deviation was analyzed. Results show that the spatial distribution, time variability and precipitation amount of summer rainfall simulated by RSM are similar to the observation, and basically present interannual variability distribution of summer precipitation, however, the simulated rain belt extended more to south and developed weaker than the observed one. Daily precipitation variation simulated by RSM was similar to the observation, representing the features that concentrated in the south and east and simulating the feature that daily rainfall in June over Jianghuai area jumped northward with time. The day number of different precipitation intensities in the simulation are generally consistent with the observation result, but the maximum centers of the simulation extended more to north compared with observation. The distribution of observed and simulated extreme precipitation indexes is similar. In conclusion, the RSM can be used to investigate the precipitation characteristics over the eastern China well.