A unifying view of climate change in the Sahel linking intra-seasonal, interannual and longer time scales
A unifying view of climate change in the Sahel linking intra-seasonal, interannual and longer time scales
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DOI：
10.1088/1748-9326/8/2/024010
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发表时间：
2013-04-01
影响因子：
6.7
通讯作者：
Ndiaye, O.
中科院分区：
文献类型：
--
作者：
Giannini, A.;Salack, S.;Ndiaye, O.
我们建议重新解释海洋对非洲萨赫勒气候的影响，这在观测、世纪模拟和21世纪世纪预测中是一致的，并解决了该地区降水变化预测的不确定性：全球热带海洋的持续变暖增加了对流的门槛，潜在地干燥了热带陆地，但是，如果季风气流中有足够的水分，就可以满足这种“增加的要求”。在这一框架内，北大西洋亚热带地区的变暖趋势逆转，现在的变暖速度超过了全球热带海洋，提供了这种水分，并解释了自1970年代和1980年代持续干旱以来降水量的部分恢复。我们发现这种恢复是由于每天降雨强度的增加，而不是频率，最明显的是在塞内加尔，最西端的三个萨赫勒国家分析。这些观察到的趋势的延续与萨赫勒地区总体湿润的预测是一致的，但在所有时间尺度上，从季节内到数十年的降水量变化更大。
We propose a re-interpretation of the oceanic influence on the climate of the African Sahel that is consistent across observations, 20th century simulations and 21st century projections, and that resolves the uncertainty in projections of precipitation change in this region: continued warming of the global tropical oceans increases the threshold for convection, potentially drying tropical land, but this 'upped ante' can be met if sufficient moisture is supplied in monsoon flow. In this framework, the reversal to warming of the subtropical North Atlantic, which is now out-pacing warming of the global tropical oceans, provides that moisture, and explains the partial recovery in precipitation since persistent drought in the 1970s and 1980s. We find this recovery to result from increases in daily rainfall intensity, rather than in frequency, most evidently so in Senegal, the westernmost among the three Sahelian countries analyzed. Continuation of these observed trends is consistent with projections for an overall wetter Sahel, but more variable precipitation on all time scales, from intra-seasonal to multi-decadal.