2003年淮河流域致洪暴雨的环流背景及其与大气热源的关系

利用NCAR/NCEP的逐日再分析资料和降水资料,分析了2003年夏季淮河流域致洪暴雨的环流背景及其与大气热源的关系.结果表明,2002-2003年的El Nino事件是本次暴雨的前期背景;南海地区的视热源和视水汽汇异常可能是副高偏南维持的重要原因之一.与2003年夏季相比较,6月21日-7月22日淮河流域为正的异常视热源和视水汽汇,并且二者的高值中心与该时段雨量中心位置基本一致.孟加拉湾地区的异常加热源在其西北侧强迫出的高层反气旋性环流有利于南亚高压在青藏高原、江南、华南地区维持,从而使得淮河流域位于高压北侧高空西风急流入口区南侧的上升运动区,有利于淮河流域强降水发生和维持,形成该流域洪涝.

The circulation background of the extremely heavy rain causing severe floods in Huaihe river valley in 2003 and its relationships to the apparent heating

Based on NCEP/NCAR daily reanalysis data and precipitation data, the circulation background of the extremely heavy rain causing severe floods in Huaihe river valley in 2003 and its relationships to the apparent heating were analyzed. The results showed that the El Nino events was the previous background of this extremely heavy rain. The abnormal apparent heating source and moist sink may be one of the important causes for subtropical high maintaining more southward than usual. Compared with summer in 2003, the positive abnormal aparent heating source and moist sink were located in the Huaihe river valley during June 21-July 22. Their centers of high value bands were in agreement with those of rainfall. The exceptional heating source over the Bay of Bengal forced an exceptional anticyclonic circulation over its northwest high level leading to the South Asian High enhancing and maintaining over the Tibetan Plateau, the south of Changjiang river valleys and South China, so Huaihe river valley areas were just located in the updraft areas which was in the south of the high-level jet, helping form heavy rain and severe floods.