Atmospheric River Signatures in Radiosonde Profiles and Reanalyses at the Dronning Maud Land Coast, East Antarctica
Atmospheric River Signatures in Radiosonde Profiles and Reanalyses at the Dronning Maud Land Coast, East Antarctica
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DOI：
10.1007/s00376-020-9221-8
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发表时间：
2020-05-01
影响因子：
5.8
通讯作者：
Hirasawa, Naohiko
中科院分区：
文献类型：
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作者：
Gorodetskaya, Irina, V;Silva, Tiago;Hirasawa, Naohiko
大气河流是连接低纬地区水汽来源和南极表面物质平衡的水文循环的重要组成部分。我们使用在2018年11月至2019年2月极地预测特别观测期期间进行的定期和额外的无线电探空仪测量，研究了东南极Dronning Maud陆地海岸大气垂直剖面的AR特征。影响Neumayer和Syowa位置的显著AR事件导致穿过对流层中部的比湿显著增加和一股强低空急流(LLJ)。在Neumayer，水汽逆温的峰值(高达4 g kg(-1))出现在800~900百帕之间，而低层急流(高达32m的S(-1))集中在900百帕以下。在西奥瓦，湿度的增加不那么明显，在地面附近达到峰值，而风速在825到925百帕之间有很大的增加(高达40米S(-1))。ARS期间垂直廓线内的水汽输送(MT)在两个位置都达到了最大100g kg(-1)m S(-1)，并且被Neumayer的ERA中期和ERA5再分析资料捕捉到，但在Syowa被严重低估。2009-19年期间增强的MT事件的合成表明，与其相对于温度、湿度、风速和MT的中值相比，这些事件代表了对流层低层轮廓的极端状态。高时间和垂直分辨率的无线电探空观测对于了解这些罕见事件对南极洲总MT的贡献并改进它们在模式中的表现是重要的。
Atmospheric rivers (ARs) are an important component of the hydrological cycle linking moisture sources in lower latitudes to the Antarctic surface mass balance. We investigate AR signatures in the atmospheric vertical profiles at the Dronning Maud Land coast, East Antarctica, using regular and extra radiosonde measurements conducted during the Year of Polar Prediction Special Observing Period November 2018 to February 2019. Prominent AR events affecting the locations of Neumayer and Syowa cause a strong increase in specific humidity extending through the mid-troposphere and a strong low-level jet (LLJ). At Neumayer, the peak in the moisture inversion (up to 4 g kg(-1)) is observed between 800 and 900 hPa, while the LLJ (up to 32 m s(-1)) is concentrated below 900 hPa. At Syowa the increase in humidity is less pronounced and peaks near the surface, while there is a substantial increase in wind speed (up to 40 m s(-1)) between 825 and 925 hPa. Moisture transport (MT) within the vertical profile during the ARs attains a maximum of 100 g kg(-1) m s(-1) at both locations, and is captured by both ERA-Interim and ERA5 reanalysis data at Neumayer, but is strongly underestimated at Syowa. Composites of the enhanced MT events during 2009-19 show that these events represent an extreme state of the lower-tropospheric profile compared to its median values with respect to temperature, humidity, wind speed and, consequently, MT. High temporal- and vertical-resolution radiosonde observations are important for understanding the contribution of these rare events to the total MT towards Antarctica and improving their representation in models.