摘要
利用1°×1°的NCEP全球再分析资料和实时高空、地面加密探测等资料,综合分析了环流背景、冷空气活动和下垫面对“云娜”台风登陆后的路径和降水变化的影响,并对“云娜”登陆后的物理量特征进行了诊断分析。结果表明:(1)台风路径在登陆时发生西折的主要原因是由于在500hPa副高调整为带状分布,台风北侧的东风气流明显加强,而且台风北侧最大东风风速与南侧的最大西风风速之差陡增;(2)冷空气的入侵是“云娜”登陆后的台风低压在其路径折向西南的主要原因,表现为850hPa台风西侧的北风加大,东侧的最大南风分量和西侧的最大北风分量的绝对值差变为负值;此外,冷空气在前期还有利于台风低压的维持,后期则使台风低压填塞;(3)“云娜”在进入鄱阳湖地区后其垂直运动、散度、水汽通量散度等各物理量场均表现出有利于降水加大的特征,这与下垫面的热量和水汽交换作用密切相关。
By using NCEP global 1°×1° re-analysis data, real-time radiosonde and intensive surface observation data, a comprehensive analysis was made of the influence of circulation background, underlying surface and cold air activity on the track and precipitation change of typhoon ＂Rananim＂ after landfall. At the same time, a diagnostic analysis was also conducted through computing the distribution of physical quantities.The results show that （1） the change of typhoon ＂Rananim＂ track from north-west to west after landfall is mainly due to the zonality of 500 hPa subtropical high, the increasing east wind near the north side of the typhoon and the sharply enhanced wind difference of absolute u component between the north and south sides before landing; （2） the intruding of cold air results in the track of the typhoon moving towards west-south during its final stage, which can be represented by the wind difference of absolute v component between the east and west sides of the typhoon, in addition, cold air is helpful for maintaining the typhoon depression circulation in the first stage, and filling it up in the final stage; （3） the ascending velocity, divergence and moisture flux all contribute to the heavy precipitation over the area of Boyang Lake when ＂Rananim＂ is moving westwards through this area, which is highly correlated to the exchange of heat and water vapor on the water surface of the lake.
出处
《热带气象学报》
CSCD
北大核心
2006年第3期229-236,共8页
Journal of Tropical Meteorology
基金
2003年上海台风研究基金
