CRA资料对一次江淮暴雨过程模拟效果的评估

利用中尺度模式WRF v4.1,分别以中国第一代全球大气/陆面再分析产品CRA、欧洲ECMWF的ERA5和美国NCEP的FNL作为初始场,对2013年7月4—6日江淮地区一次持续性暴雨过程进行了模拟试验。分析可知,此次暴雨过程是在东北冷涡、江淮切变线和西南急流3个影响系统的共同作用下,高低空冷暖空气形成对峙而导致的。与实况资料相比,3组试验均能够模拟出此次暴雨过程的主要环流形势,以及水汽、能量和动力条件。但3组试验的切变线和低空西南急流均较为偏南,强度较强,使得模拟的主要降水中心较实况位置更偏南,降水量级更大。其中CRA试验对安徽南部的水汽和垂直运动模拟更好,在该地区产生的降水也与实况更接近。而FNL试验对水汽条件和动力抬升条件模拟较弱,导致其模拟的降水明显偏小。整体而言,针对此次降水过程,ERA5模拟效果最好,CRA模拟效果接近ERA5,并且对大雨量级降水的TS(Threat Score)评分优于ERA5。

Assessment of CRA data on a Jianghuai rain storm simulation

Different initial condition supported by China''s first generation of global atmosphere and land reanalysis products (CRA), the fifth generation of ECMWF (European Center for Medium-Range Weather Forecasts) atmospheric reanalysis (ERA5) and the Final Operational Global Analysis (FNL) of NCEP(National centers for environmental prediction) on a rainstorm from July 4 to 6, 2013 in the Jiang huai regions were studied with Weather Research and Forecasting Model (WRF). Results show that the rainstorm was caused by the confrontation of cold and warm air in high and low levels under the joint action of northeast cold vortex, Jianghuai shear line and southwest jet stream. Compared with the observation data, the three experiments simulated the main circulation situation of this rainstorm, as well as the water vapor, energy and dynamic conditions. However, the shear lines and the low-level southwest jet of the three experiments were all southerly and stronger, which caused southward precipitation center and stronger precipitation magnitude. The CRA experiment showed better simulation of water vapor and vertical motion in southern Anhui, and the precipitation produced in this area was also closer to the reality. However, the FNL experiment obtained worse simulation of water vapor and dynamic conditions, which resulted in significantly weaker precipitation. Overall, for this case, ERA5 got the best simulation, while CRA''s results were close to ERA5, and its TS score of heavy rain was better than ERA5.