基于下投式探空资料的热带气旋边界层结构分析

Analysis of the kinematic and thermodynamic structure in the tropical cyclone boundary layer with the dropsonde data

本文使用来自大西洋海域5218个探空仪和西北太平洋海域448个探空仪资料,以及全球海表面温度资料、热带气旋路径资料和强度统计预测方案资料,分析了46个大西洋飓风和11个西北太平洋台风所处的环境特征和边界层结构,并对热带气旋快速增强时的边界层结构做了进一步研究.结果表明:两海域增强组热带气旋更多地受到偏北的垂直风切变的影响,增强组热带气旋所处的环境也明显比减弱组热带气旋要更加湿热;且与大西洋飓风相比,西北太平洋台风所处的环境相对湿度更大,海洋热容量亦较高;从径向分布特征来看,增强组的热带气旋总体而言边界层更加温暖,比湿相对较低;相比于快速减弱的飓风,快速增强的飓风所受到的中低层垂直风切变方向更偏向北方,所处环境更湿热,温度分布更对称,但比湿较小.研究结果能为热带气旋的强度预报特别是快速增强(减弱)的预报提供参考.

The environmental characteristics and structure of boundary layer from 46 hurricanes over the Atlantic and 11 typhoons over the Northwest Pacific was analyzed by using data of 5218 dropsondes in the Atlantic and 448 dropsondes in the Northwest Pacific,global sea surface temperature,best track and statistical intensity prediction scheme data.Furthermore,the structure of boundary layer from rapid intensifying hurricanes was further investigated.Firstly,the direction of vertical wind shear of intensifying tropical cyclones is further north.Compared to weakening group,the environmental conditions around intensifying tropical cyclones are moister and warmer.Relative humidity and ocean heat content of Northwest Pacific typhoons are larger than those of Atlantic hurricanes.Secondly,the radial distributions of variables show that tropical cyclones in the intensifying group generally have warmer boundary layer and relatively lower specific humidity.Thirdly,rapid intensifying hurricanes preferentially occurs in northerly vertical wind shear environments.Moreover,rapid intensifying hurricanes have moister environment,more symmetric temperature distribution and lower specific humidity than those of rapid weakening hurricanes.These findings provide valuable insights for tropical cyclone intensity prediction,particularly for the prediction of rapid intensifying or weakening.