The Influence of Gravity Waves on Ice Saturation in the Tropical Tropopause Layer over Darwin, Australia
Department of Atmospheric & Oceanic Sciences, University of Wisconsin–Madison, 1225 W. Dayton St., Madison, WI 53706, USA
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Atmosphere 2019, 10(12), 778; https://doi.org/10.3390/atmos10120778
Received: 25 October 2019
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Revised: 24 November 2019
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Accepted: 27 November 2019
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Published: 5 December 2019
(This article belongs to the Special Issue Gravity Waves in the Atmosphere)
Gravity waves (GWs) in the tropical tropopause layer (TTL) can help dehydrate the lower stratosphere through rapid cooling events, but observational studies of GWs in the TTL are limited. Using a long-term, high-resolution radiosonde temperature dataset, an atmospheric state classification technique, and wavelet analysis, we characterize temperature perturbations generated by GWs in the TTL over Darwin, Australia across eight atmospheric states. We find a peak in GW power just above the tropical tropopause and a climatological maximum during peak monsoon season. While accounting for a chronic negative temperature bias near the tropical tropopause, we estimate that, in the upper troposphere, GWs impose a 2 K temperature perturbation during non-monsoon states and a 3 K temperature perturbation during the monsoon states, with corresponding values of 5 K and 6 K in the upper TTL. A 3 K negative temperature perturbation will lead to significant perturbations in relative humidity with respect to ice, which has implications for environmental ice number concentrations and TTL cloud fraction.
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Keywords:
gravity waves; tropical tropopause; radiosondes; water vapor; ice saturation; clouds
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MDPI and ACS Style
Dzambo, A.M.; Hitchman, M.H.; Chang, K.-W. The Influence of Gravity Waves on Ice Saturation in the Tropical Tropopause Layer over Darwin, Australia. Atmosphere 2019, 10, 778. https://doi.org/10.3390/atmos10120778
AMA Style
Dzambo AM, Hitchman MH, Chang K-W. The Influence of Gravity Waves on Ice Saturation in the Tropical Tropopause Layer over Darwin, Australia. Atmosphere. 2019; 10(12):778. https://doi.org/10.3390/atmos10120778
Chicago/Turabian StyleDzambo, Andrew M., Matthew H. Hitchman, and Kai-Wei Chang. 2019. "The Influence of Gravity Waves on Ice Saturation in the Tropical Tropopause Layer over Darwin, Australia" Atmosphere 10, no. 12: 778. https://doi.org/10.3390/atmos10120778
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