Poleward Shift of Atmospheric Rivers in the Southern Hemisphere in Recent Decades
Poleward Shift of Atmospheric Rivers in the Southern Hemisphere in Recent Decades
复制标题
DOI：
10.1029/2020gl089934
复制
发表时间：
2020-10
影响因子：
5.2
通讯作者：
Weiming Ma;Gang Chen;B. Guan
中科院分区：
文献类型：
--
作者：
Weiming Ma;Gang Chen;B. Guan
利用三次再分析和两次共同体地球系统模式(CESM)集合研究了南半球大气河流(AR)的频率趋势。结果表明，在过去的40年里，南大洋AR频率一直在增加，而在低纬地区AR频率一直在下降，AR一直在向极地移动。虽然观测到的趋势主要是由西风急流的极移驱动的，但完全耦合的CESM实验表明，人为强迫将导致南大洋上空AR频率的正趋势，主要是由于湿度的变化。观测趋势和人类驱动趋势之间的差异可以通过观测海洋表面温度强迫的仅大气CESM模拟得到很大程度的调和：年代际太平洋涛动负相的海表面温度变率特征强烈抑制了湿气驱动趋势，而加强了南大洋环流驱动趋势，从而使模拟的趋势与观测趋势更接近。
The atmospheric river (AR) frequency trends over the Southern Hemisphere are investigated using three reanalyses and two Community Earth System Model (CESM) ensembles. The results show that AR frequency has been increasing over the Southern Ocean and decreasing over lower latitudes in the past four decades and that ARs have been shifting poleward. While the observed trends are mostly driven by the poleward shift of the westerly jet, fully coupled CESM experiments indicate anthropogenic forcing would result in positive AR frequency trends over the Southern Ocean due mostly to moisture changes. The difference between the observed trends and anthropogenically driven trends can be largely reconciled by the atmosphere‐only CESM simulations forced by observed sea surface temperatures: Sea surface temperature variability characteristic of the negative phase of the Interdecadal Pacific Oscillation strongly suppresses the moisture‐driven trends while enhances the circulation‐induced trends over the Southern Ocean, thus bringing the simulated trends into closer agreement with the observed trends.