The present study analyzes novel observations of vertical wind $(w)$ in the tropical upper troposphere-lower stratosphere obtained from a radar wind profiler in Cochin, India. Between December 2022 and April 2023, 63 consecutive 4 hr curtains of $w$ were measured with a vertical spacing of 180 m and a sampling time step of 44 s, thus resolving almost the whole spectrum of vertical motions. Spectra of $w$ strongly vary with altitude. They are generally flat up to the local Brunt-Väisälä frequency (BVF), but sometimes exhibit a peak of $w$ variance closer to BVF, a feature which may be attributed to trapped gravity waves. At other times and locations, the $w$ profiles reveal Kelvin-Helmholtz billows. Finally, the variability of $w$ variance over the 4 month campaign period is investigated. Using brightness temperature from geostationary satellites as a convective proxy, it is found that $w$ variance is highly correlated with fluctuations in convective activity.

中文翻译：

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从垂直风的雷达观测中可以看到热带 UTLS 中的高频重力波和开尔文-亥姆霍兹波涛


本研究分析了从印度科钦的雷达风廓线仪获得的热带对流层上部-平流层下部垂直风 $（w）$ 的新观测结果。在 2022 年 12 月至 2023 年 4 月期间，以 180 m 的垂直间距和 44 s 的采样时间步长测量了 63 个连续 4 小时的 $w$ 幕，从而解决了几乎所有垂直运动的范围。$w$ 的光谱随海拔高度变化很大。它们通常与当地的 Brunt-Väisälä 频率 （BVF） 持平，但有时会表现出更接近 BVF 的 $w$ 方差峰值，这一特征可能归因于被困的引力波。在其他时间和地点，$w$ 剖面揭示了开尔文-亥姆霍兹波浪。最后，调查了 4 个月活动期间 $w$ 方差的可变性。使用来自对地静止卫星的亮温作为对流代理，发现 $w$ 方差与对流活动的波动高度相关。