副热带东北太平洋海表温度异常的传递及与ENSO的联系

Propagation of the Subtropical Northeastern Pacific SSTA and Its Correlation with ENSO

厄尔尼诺-南方涛动(El Ni?o-Southern Oscillation, ENSO)现象是地球气候系统中最主要的年际变化信号之一,对其形成机制和预报的研究具有重要的理论和现实意义。本文基于ERSST v4海表面温度资料与NCEP/NCAR Reanalysis大气再分析资料,通过回归分析与合成分析等方法,研究了副热带东北太平洋海区海表面温度(sea surface temperature, SST)异常信号的传递机制及其与ENSO现象的联系。诊断结果表明,副热带东北太平洋SST异常与ENSO指数有很好的正相关关系。副热带东北太平洋SST异常的暖信号超前于ENSO指数约半年时间,通过风-蒸发-海温的反馈机制,沿东北-西南方向向赤道中太平洋缓慢传递。更进一步的数值实验显示,副热带东北太平洋的正SST异常信号的确可以影响大气环流场,使其西南方向的海面风速减弱,蒸发潜热通量减少,从而使信号向西南方向传递。

This study analyzes the propagation of the subtropical northeastern Pacific sea surface temperature anomaly(SSTA)and its correlation with El-Ni?o and southern oscillation(ENSO).Based on the extended reconstructed sea surface temperature version 4(ERSST v4)and the National Centers for Environmental Prediction/the National Center for Atmospheric Research(NCEP/NCAR)reanalysis dataset,regression analysis and synthesis analysis are carried out.The results show a positive correlation exists between the subtropical northeastern Pacific SSTA and ENSO.The subtropical northeastern Pacific SSTA leads ENSO by about six months,and propagates in the northeast-to-southwest direction to the equatorial central Pacific by the wind-evaporation-SST feedback.A series of model experiments are designed,which show that SSTA signals in the subtropical northeastern Pacific can actually influence the sea surface wind speed and latent heat flux fields,and then propagate to the southwest.