Extreme precipitation events (EPEs) are crucial in Antarctica, impacting the Antarctic ice sheet's surface mass balance and stability. Comprehensive case studies are essential for better understanding these events and the underlying processes driving them. Here, we investigate an extreme snowfall event in Dronning Maud Land (DML), East Antarctica on November 8 and 9, 2015. This event contributed approximately 22 % of the annual accumulation in less than two days and exhibited high spatial variability in precipitation distribution. We employed a high-resolution atmospheric model specifically optimized for the polar regions (Polar WRF) and ERA5 reanalysis data to analyze the event in detail. Our findings highlight the importance of a blocking high-pressure ridge of record strength that effectively blocked and diverted a strong extratropical cyclone into DML, ultimately leading to the heavy snowfall event. The sudden deepening of the cyclone was initiated by a ‘jet streak’ in the upper atmosphere that steered the system southeastwards towards the Antarctic coast. Notably, we observed an anomalously high poleward moisture transport in the form of a strong atmospheric river on November 7, 2015. This atmospheric river originated in the South Atlantic Ocean and tracked poleward from the 30°S-40°S latitude band. Vertical cross-sections of the model outputs indicate that most of the precipitation was concentrated in regions with steep orography along the path of the atmospheric river. This interaction between the atmospheric river and the steep terrain led to the uplift of maritime air, resulting in heavy snowfall. This study highlights the significance of extreme upper and lower atmospheric conditions in driving intense moisture transport towards coastal DML. The interaction between the atmospheric river and the steep orography contributed to heavy snowfall, underscoring the importance of considering orographic influences in understanding EPEs in Antarctica.

中文翻译：

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南极洲东部 Dronning Maud Land 的极端降水事件 - 使用 Polar WRF 模型的大气河流事件案例研究


极端降水事件 （EPE） 在南极洲至关重要，影响南极冰盖的表面质量平衡和稳定性。全面的案例研究对于更好地理解这些事件以及驱动这些事件的潜在过程至关重要。在这里，我们调查了 2015 年 11 月 8 日和 9 日在东南极洲的 Dronning Maud Land （DML） 发生的极端降雪事件。该事件在不到两天的时间里贡献了大约 22% 的年累积量，并且在降水分布方面表现出很高的空间可变性。我们采用了专门针对极地地区 （Polar WRF） 和 ERA5 再分析数据优化的高分辨率大气模型来详细分析事件。我们的研究结果强调了阻塞创纪录强度的高压脊的重要性，它有效地阻止了强温带气旋并将其转移到 DML，最终导致了强降雪事件。气旋的突然加深是由高层大气中的“急流条纹”引发的，该急流将该系统转向东南方向驶向南极海岸。值得注意的是，我们在 2015 年 11 月 7 日观察到了以强大气河流的形式向极地异常高的水汽输送。这条大气河流发源于南大西洋，从南纬 30°-40°S 纬度带向极地延伸。模型输出的垂直横截面表明，大部分降水集中在大气河流路径沿线地形陡峭的地区。大气河流和陡峭地形之间的这种相互作用导致海洋空气的上升，导致大雪。本研究强调了极端的高层和低层大气条件在推动强烈的水汽输送向沿海 DML 方面的重要性。 大气河流和陡峭地形之间的相互作用导致了大雪，强调了在了解南极洲 EPE 时考虑地形影响的重要性。