Century-long cooling trend in subpolar North Atlantic forced by atmosphere: an alternative explanation
Century-long cooling trend in subpolar North Atlantic forced by atmosphere: an alternative explanation
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DOI：
10.1007/s00382-021-06003-4
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发表时间：
2021-10-30
期刊：
影响因子：
4.6
通讯作者：
Li, Feili
中科院分区：
文献类型：
--
作者：
Li, Laifang;Lozier, M. Susan;Li, Feili
在整个地球仪中，一个众所周知的海表温度（SST）上升的例外是北大西洋副极地，在1900-2017年期间，SST以0.39（+/-} 0.23）K世纪（-1）的速度下降。这个冷团被假设是由于大西洋经向翻转环流（AMOC）的减速造成的。在这里，基于观测的证据被用来表明，当地的大气强迫也可以有助于长达一个世纪的冷却趋势。具体而言，100年SST趋势模拟的理想化海洋模式被迫在历史上的大气强迫冷团区域匹配92%（+/- 77%）的观测到的冷却趋势。数据驱动的模拟表明，观测到的冷却趋势中有54%（+/- 77%）是上覆大气引起的海洋热损失增加的直接结果，而其余38%是由于局部对流加强。对地面风涡动动能的分析表明，大气引起的冷却可能与急流向北迁移有关，这使副极地北大西洋暴露于更强的风暴。
A well-known exception to rising sea surface temperatures (SST) across the globe is the subpolar North Atlantic, where SST has been declining at a rate of 0.39 (+/-} 0.23) K century(-1) during the 1900-2017 period. This cold blob has been hypothesized to result from a slowdown of the Atlantic Meridional Overturning Circulation (AMOC). Here, observation-based evidence is used to suggest that local atmospheric forcing can also contribute to the century-long cooling trend. Specifically, a 100-year SST trend simulated by an idealized ocean model forced by historical atmospheric forcing over the cold blob region matches 92% (+/- 77%) of the observed cooling trend. The data-driven simulations suggest that 54% (+/- 77%) of the observed cooling trend is the direct result of increased heat loss from the ocean induced by the overlying atmosphere, while the remaining 38% is due to strengthened local convection. An analysis of surface wind eddy kinetic energy suggests that the atmosphere-induced cooling may be linked to a northward migration of the jet stream, which exposes the subpolar North Atlantic to intensified storminess.