International Laboratory for High-Resolution Earth System Prediction, Texas A&M University, College Station, TX, USA.
Department of Oceanography, Texas A&M University, College Station, TX, USA.
Nat Commun. 2021 Feb 24;12(1):1268. doi: 10.1038/s41467-021-21504-w.
Atmospheric rivers (ARs) are responsible for over 90% of poleward water vapor transport in the mid-latitudes and can produce extreme precipitation when making landfall. However, weather and climate models still have difficulty simulating and predicting landfalling ARs and associated extreme precipitation, highlighting the need to better understand AR dynamics. Here, using high-resolution climate models and observations, we demonstrate that mesoscale sea-surface temperature (SST) anomalies along the Kuroshio Extension can exert a remote influence on landfalling ARs and related heavy precipitation along the west coast of North America. Inclusion of mesoscale SST forcing in the simulations results in approximately a 40% increase in landfalling ARs and up to a 30% increase in heavy precipitation in mountainous regions and this remote impact occurs on two-week time scales. The asymmetrical response of the atmosphere to warm vs. cold mesoscale SSTs over the eddy-rich Kuroshio Extension region is proposed as a forcing mechanism that results in a net increase of moisture flux above the planetary boundary layer, prompting AR genesis via enhancing moisture transport into extratropical cyclones in the presence of mesoscale SST forcing.
大气河流（ARs）负责输送中纬度地区 90%以上的极向水汽，当它们登陆时会产生极端降水。然而，天气和气候模型仍然难以模拟和预测登陆的 ARs 及其相关的极端降水，这凸显了需要更好地了解 AR 的动力学。在这里，我们使用高分辨率气候模型和观测结果，证明了黑潮延伸带的中尺度海表温度（SST）异常可以对北美的西海岸的登陆 ARs 和相关的强降水产生远程影响。在模拟中加入中尺度 SST 强迫可以使登陆的 ARs 增加约 40%，并使山区的强降水增加高达 30%，这种远程影响发生在两周的时间尺度内。提出了一个强迫机制，即富含涡旋的黑潮延伸带区域中大气对暖中和冷中尺度 SST 的不对称响应，导致行星边界层上方的水汽通量净增加，从而在存在中尺度 SST 强迫的情况下通过增强水汽向温带气旋的输送来促使 AR 生成。
