大西洋和西太平洋海域热带气旋海表面入流角和拖曳系数特征对比分析

Comparative analysis of the characteristics of the tropical cyclone sea surface inflow angle and drag coefficient in the Atlantic and the Western Pacific oceans

本文利用大量全球定位下投式探空仪(dropsonde)资料,对15个大西洋飓风和11个西太平洋台风海域的入流角频数分布差异进行对比,探究在热带气旋不同强度和不同边界层平均风速下入流角的分布特征,分析了两个海域拖曳系数随入流角变化的趋势.结果表明,两海域在热带气旋背景下的入流角分布具有共同点:在强度更大的热带气旋里入流角的平均值更大,分布更集中,入流角在不同风速范围内均呈正态分布且差异较小;同时两海域的入流角特征也存在差异,大西洋飓风的平均入流角大于西太平洋台风,并且大西洋飓风的拖曳系数随着入流角增加而增大,而西太平洋台风的拖曳系数随入流角的增加先减小后增大.研究结果为探究热带气旋背景下入流角的作用和影响拖曳系数变化的因子提供了新的参考.

This study used extensive Global Positioning System(GPS)dropsondes from 15 Atlantic hurricanes and 11 Western Pacific typhoons to compare the difference of frequency distribution of inflow angle between the two basins and to investigate the characteristics of inflow angle under different storm intensity and different mean wind speed of the boundary layer during tropical cyclones.The relationship between drag coefficient and inflow angle in the two basins were also analyzed.The results show that there are some common characteristics of inflow angle during the tropical cyclones in the two basins:the inflow angle shows concentrated distribution in strong tropical cyclone with larger mean value,and they are normally distributed with little difference under different mean wind speed ranges.Furthermore,there are also some different characteristics of inflow angle between the two basins.The mean value of inflow angle from Atlantic hurricanes is larger than that from Western Pacific typhoons.Moreover,the drag coefficient from Atlantic hurricanes increases with the increased inflow angle,while the drag coefficient from the Western Pacific typhoons decreases firstly and then increases with the increased inflow angle.The results offer a new reference for exploring the effect of inflow angle and the factors affecting drag coefficient during tropical cyclones.