大气科学2017，Vol.41Issue(3)：437-460,24.DOI:10.3878/j.issn.1006-9895.1609.16125
季节内振荡影响西太平洋副热带高压两次北跳的机制
A Mechanism Study for the Intraseasonal Oscillation Impact on the Two Northward Jumps of the Western Pacific Subtropical High
摘要
Abstract
During summertime,the WPSH (western Pacific subtropical high) exhibits two northward jumps.The first jump signals the termination of pre-flood period in southern China and the start of the Meiyu over the Yangtze-Huaihe River valley;the second jump indicates the termination of the Meiyu and the start of rainy season in northern China.Based on the fast Fourier transformation and composite analysis of observational and reanalysis data,the authors investigated the impact of the intraseasonal oscillations (ISOs) on various timc-scales on the northward jumps in the normal and abnormal years.The dominant periods of the ISOs are different in normal and abnormal years,i.e.10-20 days and quasi-60 days in normal years,30-60 days in abnormal years of the first jump and earlier years of the second jump,10-20 days and 30-60 days in later years of the second jump.During the annual cycle,the ISOs tend to propagate northward in the East Asian-tropical northwestern Pacific region,leading to the northward jump of the WPSH.With the northeastward propagation of the ISOs over the Indian monsoon region,a more remarkable first jump is observed due to the eastward extension of the westerly.By contrast,the biweekly oscillation of the warm pool convection triggered by the cold air invasion from the Australian high plays an important role in a more evident second jump during the normal and later years.The sea surface temperature anomaly over the northwestern Indian Ocean in the preceding spring leads to the phase migration of local ISOs and associated abnormal first jump.Besides,the time-scale and amplitude of the ISOs in the warm pool can be regulated by ENSO,resulting in the abnormal second jump.关键词
季节内振荡/西太平洋副热带高压/北跳/江淮梅雨/ENSOKey words
Intraseasonal oscillation/Western Pacific subtropical high/Northward jump/Meiyu over the Yangtze Huaihe River valley/ENSO分类
天文与地球科学引用本文复制引用
苏同华,薛峰,陈敏艳,董啸..季节内振荡影响西太平洋副热带高压两次北跳的机制[J].大气科学,2017,41(3):437-460,24.基金项目
国家自然科学基金项目41405056、41475052,福建省自然科学基金青年创新项目2015J05078,华东区域气象科技协同创新基金合作项目QYHZ201405 （）
National Natural Science Foundation of China (Grants 41405056 and 41475052),Fujian Natural Science Foundation (Grant 2015J05078),East China Cooperative Innovation Foundation of Meteorological Science and Technology (Grant QYHZ201405) （Grants 41405056 and 41475052）
