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The present study analyzes novel observations of vertical wind (w) $(w)$ 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 $w$ 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 $w$ strongly vary with altitude. They are generally flat up to the local Brunt‐Väisälä frequency (BVF), but sometimes exhibit a peak of w $w$ variance closer to BVF, a feature which may be attributed to trapped gravity waves. At other times and locations, the w $w$ profiles reveal Kelvin‐Helmholtz billows. Finally, the variability of w $w$ variance over the 4 month campaign period is investigated. Using brightness temperature from geostationary satellites as a convective proxy, it is found that w $w$ variance is highly correlated with fluctuations in convective activity. Plain Language Summary: Vertical wind is a key meteorological parameter. In the tropical Upper Troposphere Lower Stratosphere (UTLS, the atmospheric layer between 14 and 20 km altitude above sea level), it crucially affects the formation of clouds and the transport of trace gases, such as water vapor, ozone and radiatively active constituents. The ensuing impacts on stratospheric composition and the Earth radiative budget have consequences for surface weather and climate. However, only a few instruments are capable of measuring vertical wind accurately in clear air, and these include VHF radars. In this study, we analyze radar measurements of UTLS vertical wind over Cochin, India taken at a 44 s sampling rate and with a vertical resolution of 180 m. Thanks to its high quality and temporal resolution, the data resolves the full spectrum of vertical motions and provides invaluable insights into the complex dynamics of the UTLS. In particular, it suggests a frequent occurrence of trapped gravity waves in this region. Trapped waves are confined vertically due to a specific vertical structure of wind and stability, but propagate long distances horizontally. The study also finds a clear relationship between vertical wind magnitude in the UTLS and convective clouds in the troposphere. Key Points: Measurements of the vertical wind throughout the upper troposphere and lower stratosphere (UTLS) from a recently built radarObservations of Kelvin‐Helmholtz billows and trapped gravity waves in the tropical UTLSImpact of convection on clear‐sky vertical wind variance in the tropical UTLS [ABSTRACT FROM AUTHOR] |
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