摘要
采用复鲜驻亚交函数展开（CEOF）等方法研究了热带海洋海表温度异常（SSTA）和北半球500hPa高度场异常（H500）的甚低频（LF）和准两年（QB）两种低频振荡的空间振幅和位相变化，发现SSTA变化信号在热带西太平洋最先出现，其后是热带中东太平洋，最后是热带印度洋和南海。副热带中西太平洋H500滞后于热带中东太平洋SSTA1-2月，H500的LF分量从副热带中西太平洋经西北太平洋至北美洲呈正负相间的驻波型振荡，而从H500的QB分量在该区域则呈现由低纬度向中高纬度传播的行进波特征。H500和SSTA的LF和QB分量极值位相都呈现一定的季节锁定特征，极端异常事件的出现与两种低频振荡的位相季节锁定的共性有关。
The time series of Fourier expansion and a weights filter are used in this paper toseparate two bands of low frequency, i. e. the quasi-biennial oscillation (QB) and 3-7 yearslowfrequency (LF). it is showm that both LF and QB widely exist in the both fields of tropical seasurface temperature anomaties (SSTA) and atmosphere geopotential height at 5OOhPa level (H500) inthe Northem Hemisphere, and that the fraction of total variance for LF is generally larger than thatof the QB constituent.The leading spatial struc1ure and the phase relation as concisely described by a set of complexempirical orthogonal functions (CEOF), revealed that the SST anomalies in the tropical West Pacificvaries out of phase, leading by l to 3 months those in the tropical Central and East Pacific andIndian Oceans. The subtropical West Pacific H500 signals lag 1-2 months those of SST anomalies inthe Central Pacific. the Variation of H500 LF component in the subtropical West and CenthelPaciflc become opposite in phase with the counterpart over the Northwest Paciflc, but the Hs500s QBsignals in this region have a slight tendency to propagate northward.The variation in phase of the low frequency oscillations, LF and QB, of SSTA in tropics andH500 in the Northem Hemisphere are closely related to annual cycles. As to the LF conshtuent forexample, most positit'e / negative extremes of SSIA in the tropical West Pacific are locked in fromJuly to August and from November to December, while the nagative/Positive extriemes of SSTA inthe tropical Central and Fast Pacitic and Indian Oceans are respechvely locked in the time laggingbehind from one to txo rnonths and two to three months to the appearance of extremes of SSTA inthe tropical West Pacific, as well as the associated negative / Positive extrcmes of H500 over thesubtropical Central and West Pacific appear in the time lagging behind from one to two months tothe appearance of extremes of SSTA in the tropical Central and East Pacific. However, the extremesof the QB constituent of the tropical SSTA and H500 are Iocked in relatively fixed months, forexamples, most posihxe/ negative extremes of SSTA in the tropical West Pacific are locked in fromJuly to August while those in the tropical Central and East Pacific and Indian Deeans are locked infrom September to October and from October to November, as well as most negative / positiveextremes of H500 are 1ocked in from November to DecemberSince both LF and QB conshtuents possess seasonal phase locking, a cedrin relahonship hasbeen found between these two kinds of low frequency oscillahons which plays an important role inthe happenings of El Ni1io, La Nifta and anomalous atmospheric general circulation.
出处
《海洋与湖沼》
CAS
CSCD
北大核心
1999年第1期97-103,共7页
Oceanologia Et Limnologia Sinica
基金
国家自然科学基金!49276250
国家气候中心开放实验室96-6LCS-02课题
关键词
甚低频振荡
准两年振荡
大气环流
SSTA
海温
CEOF Low-frequency oscillation Quasi-biennial oscillation Phase locking
