1951—2017年热带气旋移动速度特征统计分析

热带气旋移动速度是目前热带气旋研究热点之一。本文利用1951—2017年中国国家气象局最佳路径集资料,系统分析了西北太平洋海域热带气旋不同强度等级移动速度的年代际特征,初步探讨其原因,并对不同强度等级移动速度的分布特征进行系统诊断。结果表明,1951—2017年间平均移动速度(所有强度等级平均及对于大部分强度等级)呈现出减慢趋势,且主要体现在强热带气旋等级移动速度减慢;热带气旋向高纬度迁移趋势理论上将使移动速度增大而移动速度仍然减慢,说明气候因素是引起移动速度减慢的一个重要因素;不同强度等级平均移动速度、增强阶段基本相当,减弱阶段随强度减弱在初、中期明显增加,之后又逐渐减小,变性气旋移动速度显著增加;不同强度等级速度概率分布,增强阶段基本相同且相对集中,减弱阶段差异较大且相对分散,变性气旋最为分散。

Characteristic statistical for the tropical cyclone translation speed using the best track data of 1951-2017

Study of the Tropical Cyclone (TC) translation speed is a hot topic for TC research. In this paper, the best track data set of China Meteorology Agency (CMA) from 1951 to 2017 was used to analyze the TC translation speed characteristics of western North Pacific Ocean, including the decadal trend and the distribution characteristic, moreover, the possible reasons for the trend was discussed. Results show that the yearly average speed has decreased for the period of 1951 to 2017 for most of the intensity, and the slowing trend is dominated by the trend of the strong TCs. The climatic factor is an important cause contributing to the slowing trend of translation speed. Meanwhile, the average speed is almost the same for different intensity in the enhancement stage of TC, while increases notably for the early stage of the weakening stage, then decreases gradually as the intensity weakens, and the extra-TC has the largest average speed. The probability distribution of speed is relatively concentrated for different intensity in the enhancement stage, while becomes more dispersed and has larger difference for different intensity in the weakening stage, and the extra-TC shows the most dispersed property.