中期模式扰动量在广州-东莞极端暴雨中的解释应用

Interpretation and application of the anomalous parameters predicted by medium-range numerical weather forecast model in the Guangzhou-Dongguan extremely heavy rain event

2020年5月22日凌晨,在珠三角地区发生了罕见的先有高闪电密度和随后具有"短时雨强强、累积雨量大"特征的局地特大暴雨,单站5min雨强达到37.3 mm。考虑极端暴雨发生的扰动涡度动力条件和扰动湿度水汽条件,跟踪了欧洲中期天气预报中心模式分析的和提前预报的850hPa扰动气流辐合线和其上的扰动湿涡度分布。结果表明,该中心的模式可以提前4-5d预报出扰动辐合线位置,而扰动湿涡度中心与暴雨位置有偏离。中期模式产品解释应用的前景是,扰动气流辐合线和其上的扰动物理量特征可为临近强对流天气的监测提供信息。

An extremely heavy rain event,which was characterized by preceding high lightning density and thereafter the anomalous intensity of the rainfall in both the minute-scale and the hour-scale,occurred in the Pearl River Delta region in the early morning of May 22,2020.The peak 5 minute-precipitation recorded by Automatic Weather Station(AWS)was found to be up to 37.3 mm.The anomalous flow convergence line and the moist vorticity distribution at 850hPa were traced using the initially analyzed and predicted field of ECMWF,to reveal the anomalous vorticity and humidity condition favorable for the extremely heavy rain event.The results show that the anomalous flow convergence line can be predicted 4-5 days in advance by the ECMWF,while holding a bias between the predicted center of the moist vorticity and the position of the heavy rain event.One of the application prospects of the medium-range numerical weather forecast model is that the predicted anomalous flow convergence line as well as the physical parameters along it can provide critical background information for the nowcasting of the convective weather.