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利用1979—2008年NCEPⅡ月平均地表感热通量再分析资料、江苏省气象台整编的江淮出入梅日期和全国753个测站逐日降水资料,分析了亚洲北部(60°～135°E,32°～75°N,简称北亚洲)大陆冬季地表感热通量对我国江淮梅雨的影响及其可能机制。结果表明,北亚洲大陆地表在冬季总体为感热冷源,对大气起到强冷却作用。通过定义WSH指数来表征北亚洲大陆冬季地表感热冷源的强度,该指数值越小,冷源越强;反之,冷源越弱。当冬季北亚洲大陆地表感热冷源偏强时,夏季梅雨锋北侧的冷空气强度大范围加强,东北冷涡增强,且冷空气向南输送增强;7月高空副热带西风急流位置偏南,南亚高压呈青藏高压型;江淮流域上升运动增强,且该流域上空高层变干、低层变湿,大气层结的不稳定度增加,对流活动增强,有利于梅雨降水,出梅偏晚。冬季地表感热冷源偏弱时,情况则相反。因此,冬季北亚洲大陆地表感热通量的异常对汛期江淮梅雨的预测具有一定的指示意义。
Based on the NCEP II monthly mean surface heat flux reanalysis data from 1979 to 2008, the Jianghuai plume-in date and the daily precipitation data from 753 stations in the whole country, the data of monthly average surface heat fluxes from 60 ℃ to 135◦E, 32◦ ~ 75 ° N, North Asia for short) the impact of the winter sensible heat flux from the surface of the mainland on the Meiyu rainstorm of the Yangtze River and the Yellow River and its possible mechanism. The results show that the surface of the North Asian continent is generally a hot source of cold in winter and plays a strong role in cooling the atmosphere. The WSH index is used to characterize the strength of winter cold sensitive surface sources in northern Asia. The smaller the index value, the stronger the cold source. Conversely, the weaker the cold source. When the surface heat sensible cold source is strong in North Asia in winter, the intensity of cold air on the north side of summer Meiyu front strengthens broadly, the northeast cold vortex strengthens, and the cold air is transported southwards. In July, the upper-level subtropical westerly jet stream is located south and south The high pressure was in the Tibetan Autonomous Region of Tibetan Plateau. The ascending movement in the Changjiang-Huaihe River Basin was enhanced. The high-rise over the basin became dry, the low-rise became wet, the instability of the atmosphere junction increased, and the convective activity was enhanced. In winter when the surface heat source is weak, the situation is opposite. Therefore, the anomaly of the sensible heat flux over the surface of North Asia in winter is of some indication to the prediction of the plum rain in the Yangtze River and the Huai River in flood season.