Observed splitting eastbound propagation of subsurface warm water over the equatorial Pacific in early 2014

厄尔尼诺事件爆发的关键先兆因子:2014年初赤道太平洋次表层暖水的快速东传过程(英文)

El Nino, as characterized by above average sea surface temperatures in the equatorial tropical Pacific, is the largest source of natural climate variability from sea- sonal to interannual scales and can profoundly reshape the global weather patterns. Currently, the tropical Pacific Ocean appears to be primed for a potentially significant El Nino event, and some similarities exist between the oce- anic and atmospheric states in early 2014 compared to the observations shortly before the onset of the 1997/1998 Super El Nino event. For example, as one of the most important early signs of El Nino, a splitting eastbound propagation of the subsurface warm water is evident over the equatorial Pacific since January 2014. In this study, the pulses of subsurface warm water are reflected by the Kel- vin waves over the equatorial Pacific estimated from the satellite altimetry data. Results show that the current （i.e., March 2014） Kelvin wave over the equatorial Pacific has achieved the largest amplitude compared to those in the corresponding period prior to the E1 Nifio events since the availability of satellite altimetry, and is even significantly larger than the one that preceded the 1997/1998 Super El Nifio event. As the Kelvin waves can help induce El Nino conditions within about 2--4 months, the current fastest/ strongest eastbound propagation of subsurface warm water indicates that the likelihood of an El Nino event will sig- nificantly increase during the next several months in 2014.

厄尔尼诺是发生在热带中东太平洋海温异常增暖的气候现象,它是月到年际尺度全球气候变化中最重要和最强的信号.厄尔尼诺虽然发生在热带太平洋地区,但其影响却波及全球,对全球气候的短期变化有重要影响,造成世界上许多地区发生严重的旱涝和高低温灾害.2014年初,热带太平洋明显出现了厄尔尼诺事件爆发的一些前期物理信号,这些大气和海洋中呈现的前兆信号与爆发超级厄尔尼诺事件的1997年同期非常相似.本文利用卫星观测的高度计资料,精确地估计了表征次表层暖水东传过程的赤道开尔文波的变化.结果表明,相比自有1993年海表高度计卫星观测以来的6次厄尔尼诺事件,2014年3月赤道太平洋的开尔文波的向东传播速度是同期最快的,甚至明显地超过了1997年的超级厄尔尼诺事件.这些特征集中表明,2014年初的次表层暖水快速东传的现象,使得热带中东太平洋海表温度在未来几个月明显增暖,促使2014年爆发一次厄尔尼诺事件.