Stratospheric Gravity Wave Fluxes and Scales during DEEPWAVE
| Autor: | Stuart Beaton, Steven D. Eckermann, Ronald B. Smith, Jørgen Jensen, David C. Fritts, Michael Uddstrom, William A. Cooper, James D. Doyle, Michael J. Taylor, P. Romashkin, Andreas Dörnbrack, Christopher G. Kruse, Alison D. Nugent |
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| Rok vydání: | 2016 |
| Předmět: |
Atmospheric Science
Flight level 010504 meteorology & atmospheric sciences Energy flux Gravity waves atmospheric 010502 geochemistry & geophysics Atmospheric sciences 01 natural sciences Physics::Geophysics Mountain waves Scale analysis (statistics) Altitude Circulation/ Dynamics Gravity wave Stratosphere Physics::Atmospheric and Oceanic Physics Observational techniques and algorithms 0105 earth and related environmental sciences Momentum (technical analysis) Verkehrsmeteorologie Aircraft observations Atmospheric wave In situ atmospheric observations Waves Geology |
| Zdroj: | Journal of the Atmospheric Sciences. 73:2851-2869 |
| ISSN: | 1520-0469 0022-4928 |
| DOI: | 10.1175/jas-d-15-0324.1 |
| Popis: | During the Deep Propagating Gravity Wave Experiment (DEEPWAVE) project in June and July 2014, the Gulfstream V research aircraft flew 97 legs over the Southern Alps of New Zealand and 150 legs over the Tasman Sea and Southern Ocean, mostly in the low stratosphere at 12.1-km altitude. Improved instrument calibration, redundant sensors, longer flight legs, energy flux estimation, and scale analysis revealed several new gravity wave properties. Over the sea, flight-level wave fluxes mostly fell below the detection threshold. Over terrain, disturbances had characteristic mountain wave attributes of positive vertical energy flux (EFz), negative zonal momentum flux, and upwind horizontal energy flux. In some cases, the fluxes changed rapidly within an 8-h flight, even though environmental conditions were nearly unchanged. The largest observed zonal momentum and vertical energy fluxes were MFx = −550 mPa and EFz = 22 W m−2, respectively. A wide variety of disturbance scales were found at flight level over New Zealand. The vertical wind variance at flight level was dominated by short “fluxless” waves with wavelengths in the 6–15-km range. Even shorter scales, down to 500 m, were found in wave breaking regions. The wavelength of the flux-carrying mountain waves was much longer—mostly between 60 and 150 km. In the strong cases, however, with EFz > 4 W m−2, the dominant flux wavelength decreased (i.e., “downshifted”) to an intermediate wavelength between 20 and 60 km. A potential explanation for the rapid flux changes and the scale “downshifting” is that low-level flow can shift between “terrain following” and “envelope following” associated with trapped air in steep New Zealand valleys. |
| Databáze: | OpenAIRE |
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