Mayer Michael, Alonso Balmaseda Magdalena, Haimberger Leopold
Department of Meteorology and Geophysics University of Vienna Vienna Austria.
European Centre for Medium-Range Weather Forecasts Reading UK.
Geophys Res Lett. 2018 Apr 16;45(7):3274-3284. doi: 10.1002/2018GL077106. Epub 2018 Apr 6.
El Niño events are characterized by anomalously warm tropical Pacific surface waters and concurrent ocean heat discharge, a precursor of subsequent cold La Niña conditions. Here we show that El Niño 2015/2016 departed from this norm: despite extreme peak surface temperatures, tropical Pacific (30°N-30°S) upper ocean heat content increased by 9.6 ± 1.7 ZJ (1 ZJ = 10 J), in stark contrast to the previous strong El Niño in 1997/1998 (-11.5 ± 2.9 ZJ). Unprecedented reduction of Indonesian Throughflow volume and heat transport played a key role in the anomalous 2015/2016 event. We argue that this anomaly is linked with the previously documented intensified warming and associated rising sea levels in the Indian Ocean during the last decade. Additionally, increased absorption of solar radiation acted to dampen Pacific ocean heat content discharge. These results explain the weak and short-lived La Niña conditions in 2016/2017 and indicate the need for realistic representation of Indo-Pacific energy transfers for skillful seasonal-to-decadal predictions.
厄尔尼诺事件的特征是热带太平洋表层海水异常温暖以及同时出现的海洋热释放，这是随后拉尼娜冷事件的先兆。在此我们表明，2015/2016年厄尔尼诺事件背离了这一常态：尽管表层温度达到极端峰值，但热带太平洋（北纬30度至南纬30度）上层海洋热含量增加了9.6±1.7泽焦耳（1泽焦耳=10焦耳），这与1997/1998年的上一次强厄尔尼诺事件形成鲜明对比（减少了11.5±2.9泽焦耳）。2015/2016年异常事件中，印度尼西亚贯穿流的流量和热量输送出现前所未有的减少起到了关键作用。我们认为，这一异常现象与过去十年中印度洋出现的有记录的变暖加剧及海平面上升有关。此外，太阳辐射吸收增加起到了抑制太平洋海洋热含量释放的作用。这些结果解释了2016/2017年拉尼娜事件的微弱和短暂，并表明在进行准确的季节到年代际预测时，需要对印太地区的能量转移进行实际描述。
