Atmospheric Blocking and Other Large‐Scale Precursor Patterns of Landfalling Atmospheric Rivers in the North Pacific: A CESM2 Study
Atmospheric Blocking and Other Large‐Scale Precursor Patterns of Landfalling Atmospheric Rivers in the North Pacific: A CESM2 Study
复制标题
北太平洋登陆大气河的大气阻塞和其他大规模前体模式：CESM2 研究
DOI：
10.1029/2019jd030790
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Medeiros, Brian
中科院分区：
文献类型：
--
作者：
Benedict, James J.;Clement, Amy C.;Medeiros, Brian
大气河流(ARs)表现为强烈水汽输送的瞬时细丝，导致天气尺度的极端和降水的年际变化。尽管有这些影响，但导致ARS的天气尺度到行星尺度的过程仍然没有得到充分的理解。在这项研究中，在再分析资料和共同体地球系统模式版本2中都客观地确定了11-4月季节的北太平洋AR，并检查了AR登陆前1周以上的大气形势。通过在俄勒冈州(45°N，230°E)和南加州(35°N，230°E)海岸附近的采样事件，研究了AR过程的纬度相关性。俄勒冈州AR在AR登陆前1-2周出现在阿拉斯加上空，向西迁移到西伯利亚，表现出明显的反气旋，在东南亚沿海和东北太平洋发展的双中纬度气旋，以及横跨整个北太平洋盆地的纬向拉长水汽输送带，将异常的水汽引导到北美西海岸。前兆高纬度反气旋对应于大气阻塞概率的显著增加，天气涡旋活动的抑制，以及赤道前移的风暴路径。南加州ARS也表现出高纬度阻塞，但有一个较早发展和更强烈的东北太平洋气旋。与再分析相比，社区地球系统模式2将东北太平洋AR频率低估了5-20%，但总体上很好地捕捉到了AR前兆模式，特别是对俄勒冈州AR。总体而言，这些结果表明，已确定的前兆模式代表了对ARS至关重要的物理过程，而不仅仅是统计分析的产物。
Atmospheric rivers (ARs) manifest as transient filaments of intense water vapor transport that contribute to synoptic‐scale extremes and interannual variability of precipitation. Despite these influences, the synoptic‐ to planetary‐scale processes that lead to ARs remain inadequately understood. In this study, North Pacific ARs within the November–April season are objectively identified in both reanalysis data and the Community Earth System Model Version 2, and atmospheric patterns preceding AR landfalls beyond 1 week in advance are examined. Latitudinal dependence of the AR processes is investigated by sampling events near the Oregon (45°N, 230°E) and southern California (35°N, 230°E) coasts. Oregon ARs exhibit a pronounced anticyclone emerging over Alaska 1–2 weeks before AR landfall that migrates westward into Siberia, dual midlatitude cyclones developing over southeast coastal Asia and the northeast Pacific, and a zonally elongated band of enhanced water vapor transport spanning the entire North Pacific basin that guides anomalous moisture toward the North American west coast. The precursor high‐latitude anticyclone corresponds to a significant increase in atmospheric blocking probability, suppressed synoptic eddy activity, and an equatorward‐shifted storm track. Southern California ARs also exhibit high‐latitude blocking but have an earlier‐developing and more intense northeast Pacific cyclone. Compared to reanalysis, Community Earth System Model Version 2 underestimates Northeast Pacific AR frequencies by 5–20% but generally captures AR precursor patterns well, particularly for Oregon ARs. Collectively, these results indicate that the identified precursor patterns represent physical processes that are central to ARs and are not simply an artifact of statistical analysis.
登录
查看更多内容
影响因子：
8
作者：
Dacre, H. F.;Clark, P. A.;Lavers, D. A.
通讯作者：
Lavers, D. A.
DOI：
--
发表时间：
--
期刊：
--
影响因子：
--
作者：
通讯作者：
--
影响因子：
4.9
作者：
Gao, Yang;Lu, Jian;Leung, L. Ruby
通讯作者：
Leung, L. Ruby
影响因子：
3.4
作者：
S. Harris;L. Carvalho
通讯作者：
L. Carvalho
影响因子：
4.6
作者：
S. Amini;D. Straus
通讯作者：
D. Straus