与ENSO相联系的热带太平洋典型风应力异常场结构

TYPICAL WIND STRESS PATTERNS ASSOCIATED WITH THE EL NINO/SOUTHERN OSCILLATION

关键词:  海温异常  风应力异常型  ENSO

Key words:  Sea surface temperature anomaly  Wind stress anomaly patterns  ENSO

摘要:

利用多年逐月海温距平和风应力距平观测资料,运用线性回归和EOF分析方法,分析了与ENSO相联系的热带太平洋典型风应力异常场结构。结果显示,与ENSO线性相关的风应力异常场在时间尺度上表现为低频变化,在水平结构上主要表现为四个典型分布。其中,分布型1主要表现为日界线以东赤道地区东风异常和赤道风应力场辐散;分布型2主要表现为日界线以东赤道地区西风异常和经向异常风应力向赤道气流;分布型3主要表现为日界线以东赤道偏南地区西风异常和风应力场辐合,日界线以西为东风异常;分布型4主要表现为160°W以东的弱东风异常和160°W以西的西风异常。与ENSO线性无关的风应力场主要表现为高频过程,在水平空间结构上其典型场主要位于赤道外地区。还用与ENSO有关的那部分回归风应力异常场强迫海洋距平模式,成功地再现了ENSO的主要信号。这表现观测揭示的典型风应力异常型对于El Nino的产生是根本性的。

Abstract:

based on the monthly analysis data of the sea surface temperature anomaly (SSTA) and the surface wind stress anomaly,typical wind stress patterns associated with the El Nino/Southern Oscillation (ENSO) are determined with the techniques of linear regression and EOF analyses. The results show that the wind stress variation linearly associated with the ENSO is a lower frequency process and exhibits four typical spatial patterns,while the wind stress anomaly linearly independent of the ENSO seems to be a high frequency process with a typical pattern that has the large amplitude off the equator. Furthermore, an ocean anomaly model has been run in response to the typical wind stress anomaly patterns,and primarily reproduced the major signal of the ENSO. This indicates that the typical wind stress anomaly patterns presented from the observational analysis are fundamental to the El Nino.