南海热带气旋迅速加强环境场因子的影响分析  

ANALYSIS OF ENVIRONMENTAL VARIABLES OF RAPIDLY INTENSIFYING TROPICAL CYCLONES IN THE SOUTH CHINA SEA

作　　者：胡皓[1] 端义宏[1] 

机构地区：[1]中国气象科学研究院灾害天气国家重点实验室,北京100081

出　　处：《热带气象学报》2016年第3期299-310,共12页Journal of Tropical Meteorology

基　　金：国家重点基础研究发展项目(2015CB452805);国家自然科学基金项目(41375068)共同资助

摘　　要：使用中国气象局上海台风研究所整理的热带气旋最佳路径资料,对1979-2012年间南海海域热带气旋迅速加强的时空分布特征进行分析。结果表明,南海热带气旋迅速加强主要出现在夏秋两季,其中9月频数最高,空间分布主要集中在海南岛东南侧以及南海中部远离大陆的海域。基于ERA-Interim再分析资料,确定了一种环境因子的新阈值计算方法,计算出风垂直切变、高(低)层散度、低层垂直涡度、低层水汽通量散度、对流层中层相对湿度、海表面温度和海洋热含量8种环境场因子有利于迅速加强的阈值条件,结果表明风垂直切变、低层辐合、低层水汽辐合是影响迅速加强的主要因子。强台风以下级别的南海热带气旋级别越高迅速加强概率越大,迅速加强时满足阈值的因子个数也越多。除海洋热含量以外的7个因子中,满足阈值的因子个数为6个(热带风暴级别)或5个(强热带风暴级别、台风和强台风级别)时迅速加强概率最大。这些对提高南海热带气旋强度突变的预报有一定指导意义。Based on the CMA-STI tropical cyclone best track data, spatial and temporal characteristics of rapid- ly intensifying tropical cyclones （RITCs） from 1979 to 2012 are investigated. The results show that in the South China Sea （SCS） the RITCs are most likely to happen in summer and autumn and reach the highest frequency in September. Besides, spatial distribution indicates that the RITCs mainly appear to the southeast of Hainan Is- land and in the central part of SCS. Based on the ERA-Interim reanalysis data （4 times daily）, a new threshold calculation method is introduced. The threshold and probability of eight environmental variables of vertical wind shear, high and low level divergence, low level vorticity, low level moisture flux convergence, mid-level relative humidity, sea surface temperature and ocean heat content are calculated. The results show that vertical wind shear, low level convergence, and low level moisture flux convergence are the key variables associated with the RITCs. For tropical cyclones with the strength under Severe Typhoon, the stronger the intensity, the higher the probability of rapid intensification is. Without consideration of ocean heat content, we found that the probability of RITCs reach the highest when six （for Tropical Storm） or five （for Severe Tropical Storm, Typhoon ＆ Severe Typhoon） of the seven variables meet the threshold. These results could be useful in forecasting the RITCs in the SCS.

关 键 词：天气学 热带气旋迅速加强 统计分析 环境场 阈值 

分 类 号：P444[天文地球—大气科学及气象学]