Statistical Characteristics of Gravity Waves With Near-Inertial Frequencies in the Antarctic Troposphere and Lower Stratosphere Observed by the PANSY Radar
Statistical Characteristics of Gravity Waves With Near-Inertial Frequencies in the Antarctic Troposphere and Lower Stratosphere Observed by the PANSY Radar
复制标题
PANSY雷达观测的南极对流层和平流层下层近惯性频率重力波统计特征
DOI：
10.1029/2017jd028128
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Sato T.
中科院分区：
文献类型：
--
作者：
Minamihara Y.;Sato K.;Tsutsumi M.;Sato T.
重力波在时间和空间上都具有很小的尺度。由于极地地区的恶劣环境，对全球Ws的观测一直受到限制。本研究的目的是基于2015年10月1日至2016年9月30日期间的连续数据，使用南极Syowa MST/IS雷达计划（PANSY）雷达在Syowa站（69.0°S，39.6°E）的全系统，阐明南极对流层和平流层低层GWs的统计特征。这种长时间的连续观测对于任何纬度的高功率中间层-平流层-对流层（MST）雷达来说都是前所未有的。水平风脉动的频率功率谱揭示了平流层下部惯性频率（f）附近的一个明显的孤立极大值。进行了统计分析，重点是近惯性频率（NIGW）的GW，在平流层下部占主导地位。根据速端分析结果，在所有季节，以及冬季平流层15公里以上高度，对流层上层都有相当比例的NIGW向下传播能量，而群速度向上的NIGW在对流层下层和平流层最低层占主导地位。这些结果表明，在地面和对流层顶附近的所有季节和冬季平流层和/或以上的NIGW源。这些来源的合理候选者是地形、对流层急流和极地夜间急流。NIGW的水平相速度等统计特征为我们的波源推断提供了有力的支持。
Gravity waves (GWs) have temporally and spatially small scales. Observations of GWs have been limited especially in the polar region due to its harsh environment. The purpose of this study is to elucidate the statistical characteristics of GWs in the Antarctic troposphere and lower stratosphere based on the continuous data over a year from 1 October 2015 to 30 September 2016 using the full system of the Program of the Antarctic Syowa MST/IS Radar (PANSY) radar at Syowa Station (69.0°S, 39.6°E). Such continuous observations over a long duration are unprecedented for high‐power Mesosphere‐Stratosphere‐Troposphere (MST) radars at any latitude. The frequency power spectra of horizontal wind fluctuations reveal a clear isolated maximum around the inertial frequency (f) in the lower stratosphere. A statistical analysis is performed, focusing on the GWs with near‐inertial frequencies (NIGWs) that are dominant in the lower stratosphere. According to the results of hodograph analyses, there are a considerable proportion of NIGWs propagating energy downward in the upper troposphere during all seasons, as well as in the winter stratosphere above a height of 15 km, whereas NIGWs with upward group velocities are dominant in the lower troposphere and the lowermost stratosphere. These results suggest that there are NIGW sources on the ground and around the tropopause during all seasons and in the stratosphere and/or above in winter. Plausible candidates for these sources are topography, the tropospheric jet, and the polar night jet. The statistical characteristics of NIGWs, such as horizontal phase velocity, provide powerful support for our inferences of wave sources.