Numerical investigation of the quasi 2 day wave in the mesosphere and lower thermosphere

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Title:	Numerical investigation of the quasi 2 day wave in the mesosphere and lower thermosphere
Authors:	張起維;Yue, Jia;Liu, Han-Li;Chang, Loren C.
Contributors:	地球科學學院太空科學與工程學系
Keywords:	Atmosphere;Atmospheric research;Atmospheric sciences;Earth sciences;Earth, ocean, space;Exact sciences and technology;Geophysics;Internal waves;Ionosphere;numerical modeling;Oceanography;Physical oceanography;quasi 2 day wave;Seasonal variations;Summer;Tides;Wind
Date:	2012-01-01
Issue Date:	2026-04-23 11:05:14 (UTC+8)
Publisher:	Wiley-Blackwell;Washington, DC: Blackwell Publishing Ltd
Abstract:	摘要： The zonal wave number 3 planetary wave with about a 2 day period is a recurrent wave feature in the mesosphere and lower thermosphere (MLT). The quasi 2 day wave (QTDW) exhibits strong seasonal variability with peak amplitudes after summer solstice. In late January and early February, satellites also discovered two strong enhancements of the QTDW in meridional wind, one peak at summer midlatitudes near 90 km and the other in the tropical lower thermosphere. For the first time, this double‐peak characteristic of the QTDW meridional component is numerically investigated by the National Center for Atmospheric Research (NCAR) thermosphere‐ionosphere‐mesosphere‐electrodynamics general circulation model (TIME‐GCM) with the QTDW forcing prescribed at the lower model boundary and explained by the combined effect of baroclinic‐barotropic instability and Rossby normal mode. Baroclinic‐barotropic instability is capable of amplifying the QTDW, manifesting as Eliassen‐Palm (EP) flux divergence in the summer mesosphere. Without the direct contribution from baroclinic‐barotropic instability, the simulated QTDW response in a lower thermosphere temperature and horizontal wind resembles that of the (3, 0) Rossby‐gravity normal mode. In the summer middle atmosphere, the wave amplitude grows substantially, like an internal wave in the regions of large refractive index. As the wave amplitude growth ceases near the mesopause, where the zonal wind reverses direction, the QTDW reaches its maximum amplitude, displaying an enhanced meridional component in the tropical lower thermosphere. Several new aspects on the QTDWs in the MLT were also revealed. Compared with a prior model run, the propagation of the QTDW can also be prohibited by a self‐generated critical layer in a strong thermospheric easterly wind. In addition, a direct contribution from the migrating diurnal tide to the QTDW amplitude in the MLT is found. This is largely attributed to the change of the background zonal wind caused by the tide, thus leading to the increase of the QTDW refractive index in the summer middle atmosphere. 其他題名： J. Geophys. Res 出版者： Washington, DC: Blackwell Publishing Ltd 出版日期： 2012-03-16 出處： Journal of Geophysical Research Atmospheres, 2012-03, Vol.117 (D5), p.n/a 資源來源： Wiley Online Library All Journals 版權： Copyright 2012 by the American Geophysical Union 版權： 2015 INIST-CNRS 識別號： ISSN: 0148-0227 識別號： ISSN: 2169-897X 識別號： ISSN: 2156-2202 識別號： EISSN: 2156-2202 識別號： EISSN: 2169-8996 識別號： DOI: 10.1029/2011JD016574
Appears in Collections:	[DEPARTMENT OF SPACE SCIENCE AND ENGINEERING] journal & Dissertation

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