Atmospheric river variability over the last millennium driven by annular modes: Part 1 (AR tags for LME Members #2–7)

Atmospheric rivers (ARs) are filamentary structures of intense water vapor transport commonly found in the extratropical atmosphere. ARs are a crucial component of the Earth’s general circulation: ARs account for up to 90% of poleward moisture transport and are a reliable (and sometimes extreme) source of precipitation for midlatitude coastal regions around the world. Although ARs operate primarily in the extratropics, how ARs respond to extratropical climate variability remains poorly understood. In this study, we use millennium-long climate model simulations to examine how annular modes of climate variability—the dominant mode of climate variability in the extratropics in both the Northern and Southern Hemispheres—affect ARs. We find that phases of the annular modes induce strong north–south displacements in AR activity, with up to ~20–25 mm/month associated changes in precipitation. These AR changes are also found in the observational record, indicating that our model results are rep..., ,

大气河流（Atmospheric Rivers，ARs）是一类呈丝状分布的强水汽输送结构，常见于热带外大气中。ARs是地球大气总环流的关键组成部分：它们贡献了全球高达90%的极向水汽输送，同时也是全球中纬度沿海地区可靠（有时会引发极端降水）的降水来源。尽管ARs主要活动于热带外区域，但热带外气候变率对ARs的影响机制仍未得到充分解析。本研究借助长达千年的气候模式模拟试验，探究了气候环状模（Annular Modes）——南北半球热带外大气中占据主导地位的气候变率模态——对ARs的调控效应。研究发现，环状模的不同位相会引发AR活动出现显著的南北位移，伴随的降水变化幅度可达约20~25毫米/月。这类AR活动变化在观测记录中同样被观测到，表明本研究的模式结果具备可复现性（原文此处未完成）。