西北太平洋热带气旋达到不同强度时所处位置的长期趋势研究

Research in Long-Term Tendency of Tropical Cyclone Position Reaching Different Intensities over the Western North Pacific

本文利用美国联合台风预警中心(JTWC)、中国气象局上海台风研究所(CMA)及日本气象厅东京台风中心(JMA)3套热带气旋(TC)数据集,分别选取TC达到生命史极值强度时、达到台风等级时以及达到热带风暴等级时所在的位置作为研究指标,分析了1980—2013年5—11月西北太平洋TC达到不同强度时所在位置的长期变化趋势。研究得出如下结论:西北太平洋TC在达到生命史极值强度时所处的位置表现为显著向北移动的趋势,3个不同数据集向北移动趋势值分别为90、93、113 km/10a。同时TC在达到台风和热带风暴级别时还存在相对明显的向北和向西移动趋势。本文进一步从环境场出发,分析了垂直风切变、海表温度以及潜在生成指数等影响因子的变化特征,为TC达不同强度时所处位置的长期变化趋势给出可能的物理解释。

The long-term tendency of tropical cyclone (TC) position were examined when they reach the different intensities including life-time extreme, tropical storm and typhoon in this study. The data were obtained from JTWC, CMA and JMA from May to November of 1980?2013. The results indicated that TCs over the western North Pacific presented the poleward tendency at most of intensity levels, and the tendency was statistically significant in all three datasets and reached up to 90, 93 and 113 km per decade, respectively. Besides, the positions, when TCs achieved the level of typhoon and tropical storm, had relatively apparent poleward and westward tendency. By analyzing the variation characteristics of factors including vertical wind shear, sea surface temperature, and genesis potential index, further study was conducted to give a possible physical explanation for the long-term tendency.