0414号台风“云娜”登陆后西折路径和陆上维持机制的诊断分析

Diagnostic analysis on westwards turning track and sustaining over land of the landfalling typhoon 0414 "Rananim"

2004年第14号台风“云娜”在浙江省温岭市石塘镇登陆,针对登陆后的两大预报难点———路径突然西折和陆上长久维持,进行了研究分析.结果表明:台风登陆后的明显西折是由于副高突然加强造成的,地面3h变压、涡度变量、东西风分量变量等物理量对短期台风路径预报非常有用.台风陆上的长久维持与低空水汽通道的连结、高空流出气流的强辐散、登陆后的移向和特殊的下垫面等密切相关.

Typhoon 0414 ＂Rananim＂ landed at Wenling City of Zhejiang Province on August 12, 2004. The two key problems-westwards turning track abruptly and sustaining over land long were analyzed. Results demonstrate that the enhance of subtropical high is the main cause for its westward motion, physical elements such as 3h ground surface allobaric, 500hPa vorticity variability and change of u-component of wind are useful in short-range forecast of the track . It is also found that lower layer moisture channel connect with typhoon circulation, upper level strong divergence field, move towards and favorable underlying surface are associated with the sustaining of typhoon over land after landfalling.