Kelvin‐Helmholtz Billows in the Troposphere and Lower Stratosphere Detected by the PANSY Radar at Syowa Station in the Antarctic
Kelvin‐Helmholtz Billows in the Troposphere and Lower Stratosphere Detected by the PANSY Radar at Syowa Station in the Antarctic
复制标题
南极昭和站 PANSY 雷达探测到的对流层和平流层下层开尔文-亥姆霍兹波涛
DOI：
10.1029/2022jd036866
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
Tsutsumi Masaki
中科院分区：
文献类型：
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作者：
Minamihara Yuichi;Sato Kaoru;Tsutsumi Masaki
2019年，我们利用南极昭和雷达计划（PANSY雷达）和在南极昭和站获得的无线电探空仪观测结果，采用频域雷达干涉成像技术，针对对流层和平流层低层的湍流进行了两次为期10天的观测活动。检测到 73 个开尔文-亥姆霍兹 (K-H) 巨浪，并详细检查了可能由同一气旋激发的两个特征案例。在第一个最长观测持续时间为~6.5小时的情况下，K-H波涛的厚度为~800米，水平波长为~2,500米。根据数值模拟，与气旋相关的持续存在的重力波维持了足以引起 K-H 不稳定的强烈垂直风切变。在第二种情况下，最深厚度为 ∼1,600 m，K-H 波涛的水平波长为 ∼4,320 m。数值模拟表明，与发展良好的天气尺度气旋相关的增强的对流层上层急流导致了 K-H 不稳定。这种背景条件在南极沿海地区经常观察到，是 K-H 激发的典型机制。线性稳定性分析还表明，观测到的 K-H 波涛的特征与最不稳定的模式一致。此外，还使用所有 73 个观察病例的数据进行了统计分析。在昭和站观测到的 K-H 波特征与在日本上空观测到的相似。然而，昭和站上空的 K-H 巨浪往往比日本上空的波浪周期更长，这可能是由于南极对流层急流较弱。
We conducted two 10‐day observational campaigns in 2019 targeting turbulence in the troposphere and lower stratosphere by adopting a frequency domain radar interferometric imaging technique using Program of the Antarctic Syowa radar (PANSY radar) and radiosonde observations obtained at Syowa Station in the Antarctic. Seventy three Kelvin‐Helmholtz (K‐H) billows were detected, and two characteristic cases likely excited by the same cyclone were examined in detail. In the first case with the longest observational duration of ∼6.5 hr, the K‐H billows had a thickness of ∼800 m and a horizontal wavelength of ∼2,500 m. According to a numerical simulation, continuously existing gravity waves associated with the cyclone maintained strong vertical wind shear sufficient to cause the K‐H instability. In the second case with the deepest thickness of ∼1,600 m, the K‐H billows had a horizontal wavelength of ∼4,320 m. Numerical simulation suggested that an enhanced upper‐tropospheric jet associated with a well‐developed synoptic‐scale cyclone caused the K‐H instability. Such background conditions, frequently observed in the Antarctic coastal region, are typical mechanisms for K‐H excitation. Linear stability analysis also indicated that the characteristics of the observed K‐H billows were consistent with the most unstable modes. Furthermore, statistical analysis was performed using data of all 73 observed cases. The characteristics of K‐H billows observed at Syowa Station are similar to those observed over Japan. However, the K‐H billows tend to have longer wave periods over Syowa Station than over Japan, likely due to the weaker tropospheric jet in the Antarctic.