2017年7月西北太平洋热带气旋活动特征及其与北极涛动的联系  

Characteristic of tropical cyclone activity over the western North Pacific in July 2017 and its link to the arctic oscillation

作　　者：周群[1] 张润宇[1] ZHOU Qun;ZHANG Run-yu(National Marine Environmental Forecasting Center,Beijing 100081 China)

机构地区：[1]国家海洋环境预报中心,北京100081

出　　处：《海洋预报》2018年第4期1-7,共7页Marine Forecasts

基　　金：国家自然科学基金(41505050)

摘　　要：基于1961—2017年中国气象局发布的热带气旋(TC)最佳路径数据集以及NCEP再分析资料等,研究了2017年7月西北太平洋TC活动的基本特征及其与异常强的北极涛动(AO)信号之间的可能联系。结果表明:2017年7月西北太平洋季风槽以及有利于TC生成的大尺度环流因素强度偏强、位置偏西,西太平洋副热带高压偏西、偏北,从而导致西北太平洋TC生成频次明显偏多且生成源地偏西,影响和登陆我国的TC个数均较气候平均值偏多,而影响日本、韩国的TC个数偏少。进一步的分析指出2017年7月西北太平洋TC的活动异常很可能源于同期异常强的AO活动的影响。AO可以通过改变东亚-西北太平洋上空局地经圈环流,引起西太平洋副热带高压和西风环流位置和强度的变化。在AO正(负)位相年7月,造成西北太平洋TC生成位置和移动路径偏西、偏北(偏东、偏南),影响我国的台风个数偏多(偏少),影响日韩的台风个数偏少(偏多)。因此,今后在做西北太平洋台风灾害的季节预测时应考虑北极涛动的变化。The features of the tropical cyclone（TC） activity over the western North Pacific（WNP） in July 2017 and its possible link to the strong Arctic Oscillation（AO） event are analyzed by using the NCEP reanalysis dataset and TC data from CMA for the period 1961-2017. It is found that the TC genesis and landfalling-in-China are both more frequent than normal with the genesis locations drifting westward in July 2017. The diagnosis results show that the monsoon trough is stronger and moving westward, favoring the formation region of the TCs in the western part of the WNP. The easterly wind along the southern flank of the northwestward spread of the Western Pacific subtropical high（WPSH） could be contributed to more TCs impacting China. Noticing the AO is in significantly positive phase during July 2017, further investigation indicates that the AO may play a great role in the TC activities in WNP through changing the meridional circulation over the WNP-East Asia region. In a positive（negative） AO July the WPSH shifts westward（retreats eastward）, leading to the westward（eastward）shift of TC genesis location and their moving tracks, and thus the number of TCs influencing China may be above-normal（below-normal）. Therefore, anomalous AO should be taken as an important factor in the prediction of the TC activity over the WNP region in the future.

关 键 词：西北太平洋 热带气旋 西太平洋副热带高压 北极涛动 

分 类 号：P444[天文地球—大气科学及气象学]