北太平洋海温对ENSO事件响应的持续性

The persistence of the North Pacific SST response to ENSO events

北太平洋海温的异常变化对海洋生态系统以及全球天气和气候都有重要影响。北太平洋海温主要受ENSO的影响,并可以从ENSO盛期冬季一直延续到ENSO衰减年春季,存在明显的持续性。然而,2000年前ENSO的影响仅能维持至次年2月,2000年后却能持续至5月,其持续性呈明显的年代际增强。基于再分析数据探讨这一年代际变化的特征以及可能的物理机制。结果表明,ENSO事件对冬、春季北太平洋海温影响持续性在2000年后的增强,主要受到北太平洋区域经向平流反馈及海表热通量反馈控制。2000年前,由ENSO激发的遥相关波列在春季已经减弱,热通量的反馈作用使得海温上升。而在2000年之后,冬季偏西的海温异常使赤道对流可以在次年春季长时间维持在国际日期变更线附近,持续激发大气遥相关波列导致北太平洋上空在春季仍然存在显著的气旋性环流异常,并通过经向平流反馈及热通量反馈使局地海温维持偏低状态,对ENSO产生持续响应,增强ENSO事件对其影响的持续性。

The anomalies of Sea Surface Temperature(SST)over the North Pacific have significant impacts on marine ecosystemsand global weather and climate.The North Pacific SST is primarily influenced by ENSO and shows a clear persistence.However,itsduration manifests an interdecadal enhancement.Before 2000,the impact of ENSO only lasted until February of the following year;after 2000,however,it could extend until May.Based on reanalysis data,this study explores the characteristics of this interdecadalchange and the potential physical mechanisms behind it.The results indicate that the enhanced persistence of ENSO impact on thewinter—spring North Pacific SST is mainly controlled by the meridional advection feedback and the sea surface heat flux feedbackover the North Pacific.Before 2000,the teleconnection triggered by ENSO had already weakened in spring,leading to high SST dueto the heat flux feedback.However,after 2000,the SST anomaly to the west of its normal location during winter allowed equatorialconvection to persist near the dateline until the following spring.The persistent convection continuously triggered remoteatmospheric teleconnection and resulted in significant cyclonic circulation anomalies over the North Pacific.These anomalouscirculations finally led to low SST through meridional advection feedback and heat flux feedback,and thereby enhanced thepersistence of the North Pacific SST response to ENSO events.