Freshwater forcing control on early-Holocene South American monsoon
Freshwater forcing control on early-Holocene South American monsoon
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DOI：
10.1016/j.quascirev.2020.106498
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发表时间：
2020-10-01
影响因子：
4
通讯作者：
Mata, Mauricio M.
中科院分区：
文献类型：
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作者：
Aguiar, Wilton;Prado, Luciana F.;Mata, Mauricio M.
阿加西湖暴发和哈德逊湾冰盖融化导致的气候异常通常被认为是北美大气降温的触发因素。然而，在南半球，这些淡水通量主要与降水增加和南美洲季风系统(SAMS)的可能加强有关。在这里，我们测试了SAMS对全新世早期融水事件的反应。基于代理资料和模拟，我们发现海表面温度(SSTs)和降水表明由于南大西洋副热带偶极子的减弱，淡水驱动的SAMS增强。模拟的SAMS增强可以解释南美洲全新世早期降水变化的50%。反过来，南大西洋副热带偶极子的变化占南大西洋海温变化的31%。此外，我们认为，全新世早期较强的SAMS可能是由于淡水驱动的东南信风减弱所致。较慢的信风减弱了纬向和经向地表水的输送，将温暖的海水集中在南大西洋东北部。(C)2020爱思唯尔有限公司。保留所有权利。
Climate anomalies due to Lake Agassiz outbursts and Hudson Bay ice dome melting are commonly considered triggers of North American atmospheric cooling. However, in the Southern Hemisphere, these freshwater fluxes are mostly associated with increased precipitation and a possible intensification of the South American Monsoon System (SAMS). Here, we tested how the SAMS responded to early-Holocene meltwater events. Based on both proxy data and simulations, we find that sea surface temperatures (SSTs) and precipitation indicate a freshwater-driven strengthening of the SAMS due to a weakening of the South Atlantic subtropical dipole. Simulated SAMS strengthening accounts for up to 50% of the variance in early-Holocene precipitation in South America. In turn, changes in the South Atlantic Subtropical Dipole accounts for up to 31% of the variance in South Atlantic SSTs. Additionally, we propose that the stronger SAMS in the early Holocene might have been due to a freshwater-driven weakening of the southeasterly trade winds. Slower trade winds weaken the zonal and meridional surface water transport, concentrating warm waters in the northeastern South Atlantic. (C) 2020 Elsevier Ltd. All rights reserved.