Emerging negative Atlantic Multidecadal Oscillation index in spite of warm subtropics.
Emerging negative Atlantic Multidecadal Oscillation index in spite of warm subtropics.
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DOI：
10.1038/s41598-017-11046-x
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发表时间：
2017-09-11
影响因子：
4.6
通讯作者：
Duchez A
中科院分区：
文献类型：
--
作者：
Frajka-Williams E;Beaulieu C;Duchez A
北大西洋北部的海面温度在过去几年中有明显的下降。亚极环流的海面现在和20世纪90年代大西洋多年代际振荡指数的最后一个冷期一样冷。这一气候指数与飓风活动、降雨模式和强度的变化以及鱼类种群的变化有关。然而，与大西洋上一次冷期不同的是，大西洋海表温度异常的空间格局并非均匀凉爽，而是亚极环流温度异常寒冷，亚热带温度异常温暖，热带上空温度异常凉爽。异常的三极型增加了海温的亚极至副热带经向梯度，而AMO指数值并不能反映这一梯度，但可能导致大气斜压性和风暴性的增加。在这里，我们表明，最近大西洋的冷却很可能会持续下去，正如对地下海洋温度的统计预测所预测的那样，这与最近亚极地环流冷却所涉及的水团变化的不可逆性是一致的。
Sea surface temperatures in the northern North Atlantic have shown a marked decrease over the past several years. The sea surface in the subpolar gyre is now as cold as it was during the last cold phase of the Atlantic Multidecadal Oscillation index in the 1990s. This climate index is associated with shifts in hurricane activity, rainfall patterns and intensity, and changes in fish populations. However, unlike the last cold period in the Atlantic, the spatial pattern of sea surface temperature anomalies in the Atlantic is not uniformly cool, but instead has anomalously cold temperatures in the subpolar gyre, warm temperatures in the subtropics and cool anomalies over the tropics. The tripole pattern of anomalies has increased the subpolar to subtropical meridional gradient in SSTs, which are not represented by the AMO index value, but which may lead to increased atmospheric baroclinicity and storminess. Here we show that the recent Atlantic cooling is likely to persist, as predicted by a statistical forecast of subsurface ocean temperatures and consistent with the irreversible nature of watermass changes involved in the recent cooling of the subpolar gyre.
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