西北太平洋8月热带气旋频数异常特征分析  

Characteristics analysis of abnormal tropical cyclone frequency in august in the Northwest Pacific

作　　者：倪文琪 蒋国荣[2] 陈弈德[2] 杜振彩 卢姁 令聪婧 韦道明 郁红弟 康建伟 

机构地区：[1]解放军61741部队 [2]解放军理工大学

出　　处：《海洋预报》2017年第1期47-56,共10页Marine Forecasts

基　　金：国家自然科学青年基金(41306010)

摘　　要：利用1949—2014年的美国国家环境预报中心2.5°×2.5°的月平均资料和上海台风研究所提供的台风年鉴,对西北太平洋8月热带气旋频数异常进行了统计相关和合成分析,并通过对台风异常偏少的2014年进行诊断分析,使相关和合成结果得到验证。主要结论有:(1)西北太平洋8月台风频数和赤道、副热带区域500 h Pa位势高度、当年4—7月该区域的异常位势高度均有显著负相关;与孟加拉湾北部SST、赤道中东太平洋850 h Pa纬向风场和印缅地区地面低压系统也有显著关联;(2)台风少年孟加拉湾北部SST偏高,极涡中心值偏低,副高强度强,北半球位势高度梯度小,东亚大槽浅,而多年则相反;(3)8月台风偏多(少)年低频能量的位相分布完全相反,传播特征明显不同。偏多年在6月中旬和8月上旬为正位相,偏少年相反;多年表现为系统西传,少年为东传;(4)2014年8月台风异常偏少的原因有:西太平洋副高位置偏南;赤道中太平洋SST异常增暖造成沃克环流发生异常;季风槽位置较常年明显偏西强度显著偏弱;(5)2014年的环流形势属于典型的台风偏少型,验证了历史相关统计和合成结果。Using 2.5°× 2.5° monthly average data from 1949 to 2014 from National Centers for Environmental Prediction and typhoon yearbook by Shanghai Typhoon Institute, the statistical correlation and synthetic analysis towards the abnormal typhoon frequency in August are made through analyzing the reason of fewer Tropical Cyclone（TC） frequency in August 2014 and the related and synthetic results are verified. The conclusions are 1） typhoon frequency in August in the northwest Pacific has significant negative correlation with the geopotential height on 500hPa at the equator and subtropical area, abnormal equatorial geopotential height in April-July in the same year ; it also has significant correlation with the SST of the northern bay of Bengal, zonal wind field on 850hPa at middle-east equator Pacific Ocean and low pressure system of Indian-Burma area. 2） In fewer typhoon years, the SST of the northern bay of Bengal is higher, the value of polar vortex center is lower, the subtropical high is stronger, geopotential height gradient of the northern hemisphere is small, east Asia trough is shallow, while oppositely in more typhoon years. 3） The phases of low frequency energy are entirely opposite in more and less typhoon years, propagation characteristics are obviously different. For more typhoon years, positive phases appear in the middle of June and early August, while fewer years are opposite; For more typhoon years, propagation characteristic is systematically westward, while eastward in fewer years. 4） The causes of abnormal fewer typhoon frequency in August 2014 are that the location of western Pacific subtropical high is further south, anomaly of walker circulation happens while the influence of anomaly higher middle equatorial Pacific SST, position of monsoon trough is obvious westward, and intensity is significantly weaker. 5） The situations in 2014 belongs to representative fewer typhoon type, which coincides with the historical statistics and synthetic results.

关 键 词：8月台风频数 SST诊断分析 相关 大气ISO 低频传播 

分 类 号：P444[天文地球—大气科学及气象学]