Relationship Between Weather Regimes and Atmospheric Rivers in East Antarctica
Relationship Between Weather Regimes and Atmospheric Rivers in East Antarctica
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DOI：
10.1029/2021jd035294
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发表时间：
2021-12
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影响因子：
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通讯作者：
B. Pohl;V. Favier;J. Wille;Danielle G. Udy;T. Vance;J. Pergaud;Niels Dutrievoz;J. Blanchet;C. Kittel;C. Amory;G. Krinner;Francis Codron
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作者：
B. Pohl;V. Favier;J. Wille;Danielle G. Udy;T. Vance;J. Pergaud;Niels Dutrievoz;J. Blanchet;C. Kittel;C. Amory;G. Krinner;Francis Codron
在这里，我们根据1979-2018年ERA5再分析得出的700百帕位势高度的日异常来定义东南极-南大洋部分的天气状况。大多数体制及其首选的过渡描述了天气尺度扰动在南极海岸线外向东传播。虽然气候序列一般都很短，但它们的年际变化很大程度上是由南环状模式(SAM)的极性驱动的。然后，在同一地区和同一时期内探测到的大气河流(AR)与系统发生的情况相交。ARA全年都有同样的可能性，但明显集中在与区域东部的强大气脊线/阻塞有关的区域，这些区域的作用是将来自较低纬度的热量和水汽经向平流输送到南极洲。这两种制度和区域气候变化都极大地影响了南极洲的气候变化。有利于AR发生的体制与南极洲沿海的异常温暖和潮湿条件有关，在较小程度上与南极高原腹地有关。这些异常在AR事件期间被强烈增强，变暖的异常和显著放大的降雪量。最后探索了有利于AR发展的规模化条件。它们表现出对SAM的弱依赖性，但特别是南大洋上空的强大气脊线/阻塞似乎是最有利的模式，ARs可以嵌入其中，并对其做出贡献。
Here, we define weather regimes in the East Antarctica—Southern Ocean sector based on daily anomalies of 700 hPa geopotential height derived from ERA5 reanalysis during 1979–2018. Most regimes and their preferred transitions depict synoptic‐scale disturbances propagating eastwards off the Antarctic coastline. While regime sequences are generally short, their interannual variability is strongly driven by the polarity of the Southern Annular Mode (SAM). Regime occurrences are then intersected with atmospheric rivers (ARs) detected over the same region and period. ARs are equiprobable throughout the year, but clearly concentrate during regimes associated with a strong atmospheric ridges/blockings on the eastern part of the domain, which act to channel meridional advection of heat and moisture from the lower latitudes towards Antarctica. Both regimes and ARs significantly shape climate variability in Antarctica. Regimes favorable to AR occurrences are associated with anomalously warm and humid conditions in coastal Antarctica and, to a lesser extent, the hinterland parts of the Antarctic plateau. These anomalies are strongly enhanced during AR events, with warmer anomalies and dramatically amplified snowfall amounts. Large‐scale conditions favoring AR development are finally explored. They show weak dependency to the SAM, but particularly strong atmospheric ridges/blockings over the Southern Ocean appear as the most favorable pattern, in which ARs can be embedded, and to which they contribute.