Reconciling roles of sulphate aerosol forcing and internal variability in Atlantic multidecadal climate changes
Reconciling roles of sulphate aerosol forcing and internal variability in Atlantic multidecadal climate changes
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DOI：
10.1007/s00382-019-04811-3
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发表时间：
2019-10-01
期刊：
影响因子：
4.6
通讯作者：
Tatebe, Hiroaki
中科院分区：
文献类型：
--
作者：
Watanabe, Masahiro;Tatebe, Hiroaki
北大西洋的年代际盆地范围的变暖和变冷循环，称为大西洋数十年变率（AMV），不仅影响欧洲大西洋的气候条件，还远程影响热带风暴和季风。然而，关于过去 AMV 的外部强迫和内部过程的相对重要性仍然存在争议。在这里，我们使用 1931-2014 年气候模型的三个归因实验，每个归因实验由五名成员组成，结果表明，观测到的 AMV 的时间变化可以在辐射强迫历史变化的模型中重现。具体来说，人为硫酸盐排放可以解释十年时间尺度上 46-63% 的强制海表温度变化。该模型还很好地捕捉到了与 AMV 相关的海面温度 (SST) 的空间模式，其中外部强迫成分占主导地位，并在正 AMV 期间显着增加了欧洲和萨赫勒地区的降水量。副极地地区是一个例外，内部产生的海温变化与北大西洋涛动一起发挥了主要作用。在人为气溶胶排放量下降的情况下，气候模拟的多模型集合表明，北大西洋十年海温变化将越来越多地由内部过程产生，这表明对区域降水的影响正在减少。
The interdecadal basin-wide warming and cooling cycle of the North Atlantic Ocean, known as the Atlantic multidecadal variability (AMV), influences not only the Euro-Atlantic climatic conditions, but also tropical storms and monsoons remotely. However, controversy still remains on the relative importance of external forcing and internal processes for the past AMV. Here, we use three attribution experiments, consisting of five-member ensemble for each, for 1931-2014 by a climate model and show that the temporal variation of the observed AMV can be reproduced in the model forced by historical changes in radiative forcing. Specifically, anthropogenic sulphate emissions are found to explain 46-63% of the forced SST variations at decadal time scales. The spatial pattern of the sea surface temperature (SST) associated with the AMV is also well captured by the model, in which externally forced components dominate and significantly increase precipitation over Europe and the Sahel during positive AMV. An exception is the subpolar region where internally generated SST variability coupled with the North Atlantic Oscillation plays a major role. Under declining scenarios of anthropogenic aerosol emissions, a multi-model ensemble of climate simulations shows that the North Atlantic decadal SST variability will be generated increasingly by internal processes, suggesting a decreasing impact on regional precipitation.