Linking Sub‐Tropical Evaporation and Extreme Precipitation Over East Antarctica: An Atmospheric River Case Study
Linking Sub‐Tropical Evaporation and Extreme Precipitation Over East Antarctica: An Atmospheric River Case Study
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将副热带蒸发与东南极洲极端降水联系起来：大气河案例研究
DOI：
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
H. Sodemann
中科院分区：
文献类型：
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作者：
A. Terpstra;I. Gorodetskaya;H. Sodemann
我们调查了2011年2月15日至18日在东南极沿海地区发生的一次强烈降雪事件，该事件约占年积雪总量的24%。该事件以前与大气河流有关，这里我们使用欧拉分析和拉格朗日分析来了解影响大气河流特征的过程。事件期间的行星尺度结构包括持续的阻塞情况，导致从亚热带到南极冰盖在20至50°E之间持续的经向气流。在这种结构中，天气尺度的气旋发生有助于湿气气团向南极洲倾斜上升。该气旋暖区的登陆恰逢南极降水开始。随后，一个二次气旋沿着先前存在的斜压区发展。这一中尺度气旋在温暖潮湿的气团旁迅速加强和传播，导致气旋之前的水汽通量汇聚很强，提供了额外的向极地的水汽输送。暖湿空气的极地推进和相应的海面温度下降意味着整个极地强湿润区域的地面感热和潜热通量向下移动，大约在40至60°S之间。因此，副热带和极地大陆之间通过表面蒸发吸收的水汽受到抑制，有利于远距离输送。通过跟踪气团中水分的变化来确定地表吸湿区，证实了在本研究中向极地输送过程中吸湿量有限，南极降水的主要水汽来源位于亚热带。
We investigate an intense snowfall event between 15 and 18 February 2011 over the East Antarctic coastal region which contributed to roughly 24% of the annual snow accumulation. The event was previously associated with an atmospheric river, and here we use both Eulerian and Lagrangian analysis to gain an understanding of the processes contributing to the atmospheric river signature. The planetary‐scale configuration during the event consisted of a persistent blocking situation resulting in a sustained meridional flow from the sub‐tropics to the Antarctic ice sheet between 20 and 50°E. Within this configuration, synoptic‐scale cyclogenesis contributed to slantwise ascent of moisture loaded air parcels toward Antarctica. Landfall of this cyclone’s warm sector coincided with the onset of Antarctic precipitation. Subsequently, a secondary cyclone developed along a pre‐existing baroclinic zone. The rapid intensification and propagation speed of this mesoscale cyclone alongside the warm, moist air mass resulted in strong moisture flux convergence ahead of the cyclone, providing additional poleward moisture transport. The poleward progression of warm moist air and a corresponding decrease of sea‐surface temperatures implied downward surface sensible and latent heat fluxes throughout the region of intense poleward moisture, roughly between 40 and 60°S. Hence, moisture uptake via surface evaporation was suppressed between the sub‐tropics and the polar continent, favoring long‐range transport. Identification of the surface moisture uptake region by tracing changes in moisture in air parcels confirmed the limited uptake of moisture during the poleward transport in this case study, with the primary moisture source for Antarctic precipitation located in the sub‐tropics.
影响因子：
5.2
作者：
Gorodetskaya, I. V.;Kneifel, S.;Van Lipzig, N. P. M.
通讯作者：
Van Lipzig, N. P. M.
影响因子：
3.8
作者：
Maahn, M.;Kollias, P.
通讯作者：
Kollias, P.