高原强对流和高原涡东移的协同作用对下游强降水过程的影响

Synergistic Effect of Tibetan Plateau Severe Convection and Tibetan Plateau Vortex Eastward-Propagating on the Downstream Heavy Precipitation Process

  • 摘要: 基于印度静止气象卫星高分辨OLR资料、国家气象科学数据中心降水资料和ERA5再分析资料,诊断分析了2016年6月28日12时—7月1日12时(世界时,下同)在青藏高原强对流与高原涡东移协同作用下诱发的一次高原及其下游地区极端强降水天气过程。结果表明:高原强对流和高原涡东移之间的反馈协同作用对高原及下游川东到江淮流域的极端强降水过程有重要影响。首先,2016年6月28日高原涡在高原西部生成并激发高原对流,6月29日高原对流在高原涡的反馈作用下加强东移,高原中部强对流中心OLR值低于110 W/m2,高原上出现区域性强降水。随后,高原强对流伴随高原涡东移,高原涡移出高原后演变为低压槽向东移动;同时受对流层中有利于垂直上升运动和对流东移加强的一致性环流条件影响,对流发展异常强烈,导致6月30日—7月1日川渝至江淮地区出现持续性强降水过程,尤其是湖北东部到安徽西部有6个台站24 h降水量高于200 mm,3个站甚至高于300 mm,远超99百分位的极端降水阈值。

     

    Abstract: Based on high-resolution OLR data from the Indian geostationary meteorological satellite, the precipitation data obtained by the National Meteorological Science Data Center and ERA5 reanalysis data, a severe precipitation event over the Tibetan Plateau (TP) and its downstream areas induced by the synergistic effect of strong convection over the TP and the eastward movement of the Tibetan Plateau vortex (TPV) from 12UTC on June 26th to 12UTC on July 1st, 2016 was diagnosed and analyzed. The results indicate that the feedback synergy between the strong convection over the TP and the eastward movement of the TPV has a significant impact on the extreme heavy precipitation process over the TP and its downstream from the eastern Sichuan to the Jianghuai River basin. First of all, on June 28th, 2016, the TPV generated in the west of the TP and stimulated the Tibetan Plateau convection. On June 29th, the Tibetan Plateau convection strengthened and moved eastward under the feedback of the TPV. The OLR value of the strong convection centre in the central plateau was lower than 110W/m2, and there was a regional heavy precipitation on the TP. Subsequently, the strong convection over the TP moved eastward with the TPV, and the TPV evolved into a low-pressure trough moving eastward after moving out of the plateau. At the same time, due to the influence of the consistent circulation conditions in the troposphere, which was conducive to the vertical upward movement and the eastward movement of convection, the convection development was extremely strong, leading to a sustained heavy rainfall process from June 30th to July 1st from Sichuan-Chongqing to Jianghuai regions of China. Especially, from eastern Hubei to western Anhui, there were 6 stations with 24-hour precipitation higher than 200 mm, and 3 stations even higher than 300 mm, far exceeding the extreme precipitation threshold of 99 percentile.

     

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