Numerical simulation of wave interactions during sudden stratospheric warming
Autor: | Alexander Pogoreltsev, A. V. Koval, Nikolai M. Gavrilov, E. N. Savenkova |
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Rok vydání: | 2017 |
Předmět: |
Atmospheric Science
010504 meteorology & atmospheric sciences Atmospheric circulation Northern Hemisphere Flux Sudden stratospheric warming Oceanography Atmospheric sciences 01 natural sciences Latitude Atmosphere 0103 physical sciences 010303 astronomy & astrophysics Southern Hemisphere Geology 0105 earth and related environmental sciences Orographic lift |
Zdroj: | Izvestiya, Atmospheric and Oceanic Physics. 53:592-602 |
ISSN: | 1555-628X 0001-4338 |
DOI: | 10.1134/s0001433817060044 |
Popis: | Parameterizations of normal atmospheric modes (NAMs) and orographic gravity waves (OGWs) are implemented into the mechanistic general circulation model of the middle and upper atmosphere (MUA). Numerical experiments of sudden stratospheric warming (SSW) events are performed for climatological conditions typical for January and February using meteorological reanalysis data from the UK MET Office in the MUA model averaged over the years 1992–2011 with the easterly phase of quasi-biennial oscillation (QBO). The simulation shows that an increase in the OGW amplitudes occurs at altitudes higher than 30 km in the Northern Hemisphere after SSW. The OGW amplitudes have maximums at altitudes of about 50 km over the North American and European mountain systems before and during SSW, as well as over the Himalayas after SSW. At high latitudes of the Northern Hemisphere, significant (up to 50–70%) variations in the amplitudes of stationary planetary waves (SPWs) are observed during and after the SSW. Westward travelling NAMs have local amplitude maximums not only in the Northern Hemisphere, but also in the Southern Hemisphere, where there are waveguides for the propagation of these modes. Calculated variations of SPW and NAM amplitudes correspond to changes in the mean temperature and wind fields, as well as the Eliassen-Palm flux and atmospheric refractive index for the planetary waves, during SSW. Including OGW thermal and dynamical effects leads to an increase in amplitude (by 30–70%) of almost all SPWs before and during SSW and to a decrease (up to 20–100%) after the SSW at middle and high latitudes of the Northern Hemisphere. |
Databáze: | OpenAIRE |
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