Zhang Shipeng, Stier Philip, Dagan Guy, Wang Minghuai
Department of Physics Atmospheric, Oceanic and Planetary Physics University of Oxford Oxford UK.
Institute of Earth Sciences Hebrew University of Jerusalem Jerusalem Israel.
Geophys Res Lett. 2022 Jan 16;49(1):e2021GL095629. doi: 10.1029/2021GL095629. Epub 2021 Dec 28.
The Sahel rainfall has a close teleconnection with North Atlantic sea surface temperature (NASST) variability, which has separately been shown to be affected by aerosols. Therefore, changes in regional aerosols emission could potentially drive multidecadal Sahel rainfall variability. Here we combine ensembles of state-of-the-art global climate models (the CESM and CanESM large ensemble simulations and CMIP6 models) with observational data sets to demonstrate that anthropogenic aerosols have significantly impacted 20th-century detrended Sahel rainfall multidecadal variability through modifying NASST. We show that aerosol-induced multidecadal variations of downward solar radiative fluxes over the North Atlantic cause NASST variability during the 20th century, altering the ITCZ position and dynamically linking aerosol effects to Sahel rainfall variability. This process chain is caused by aerosol-induced changes in radiative surface fluxes rather than changes in ocean circulations. CMIP6 models further suggest that aerosol-cloud interactions modulate the inter-model uncertainty of simulated NASST and potentially the Sahel rainfall variability.
萨赫勒地区的降雨与北大西洋海表温度（NASST）变化存在密切的遥相关，而NASST变化已被分别证明受到气溶胶的影响。因此，区域气溶胶排放的变化可能会驱动萨赫勒地区降雨的年代际变化。在这里，我们将最先进的全球气候模型集合（CESM和CanESM大型集合模拟以及CMIP6模型）与观测数据集相结合，以证明人为气溶胶通过改变NASST对20世纪去趋势化的萨赫勒地区降雨年代际变化产生了显著影响。我们表明，气溶胶引起的北大西洋向下太阳辐射通量的年代际变化导致了20世纪的NASST变化，改变了热带辐合带的位置，并将气溶胶效应与萨赫勒地区降雨变化动态联系起来。这个过程链是由气溶胶引起的辐射表面通量变化而非海洋环流变化导致的。CMIP6模型进一步表明，气溶胶-云相互作用调节了模拟NASST的模型间不确定性以及潜在的萨赫勒地区降雨变化。
