Eastward-propagating planetary waves in the polar middle atmosphere

<p>According to Modern-Era Retrospective Research Analysis for Research and Applications (MERRA-2) temperature and wind datasets in 2019, this study presents the global variations in the eastward-propagating wavenumber 1 (E1), 2 (E2), 3 (E3) and 4 (E4) planetary waves (PWs) and their diagnosti...

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Autores principales:	L. Tang, S.-Y. Gu, X.-K. Dou
Formato:	article
Lenguaje:	EN
Publicado:	Copernicus Publications 2021
Materias:	Physics QC1-999 Chemistry QD1-999
Acceso en línea:	https://doaj.org/article/6210ae12c5d74e7f96975d43dc25cfb4
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spelling	oai:doaj.org-article:6210ae12c5d74e7f96975d43dc25cfb42021-12-01T14:23:18ZEastward-propagating planetary waves in the polar middle atmosphere10.5194/acp-21-17495-20211680-73161680-7324https://doaj.org/article/6210ae12c5d74e7f96975d43dc25cfb42021-12-01T00:00:00Zhttps://acp.copernicus.org/articles/21/17495/2021/acp-21-17495-2021.pdfhttps://doaj.org/toc/1680-7316https://doaj.org/toc/1680-7324<p>According to Modern-Era Retrospective Research Analysis for Research and Applications (MERRA-2) temperature and wind datasets in 2019, this study presents the global variations in the eastward-propagating wavenumber 1 (E1), 2 (E2), 3 (E3) and 4 (E4) planetary waves (PWs) and their diagnostic results in the polar middle atmosphere. We clearly demonstrate the eastward wave modes exist during winter periods with westward background wind in both hemispheres. The maximum wave amplitudes in the Southern Hemisphere (SH) are slightly larger and lie lower than those in the Northern Hemisphere (NH). Moreover, the wave perturbations peak at lower latitudes with smaller amplitudes as the wavenumber increases. The period of the E1 mode varies between 3–5 d in both hemispheres, while the period of the E2 mode is slightly longer in the NH (<span class="inline-formula">∼</span> 48 h) than in the SH (<span class="inline-formula">∼</span> 40 h). The periods of the E3 are <span class="inline-formula">∼</span> 30 h in both the SH and the NH, and the period of E4 is <span class="inline-formula">∼</span> 24 h. Despite the shortening of wave periods with the increase in wavenumber, their mean phase speeds are relatively stable, <span class="inline-formula">∼</span> 53, <span class="inline-formula">∼</span> 58, <span class="inline-formula">∼</span> 55 and <span class="inline-formula">∼</span> 52 m/s at 70<span class="inline-formula"><sup>∘</sup></span> latitudes for E1, E2, E3 and E4, respectively. The eastward PWs occur earlier with increasing zonal wavenumber, which agrees well with the seasonal variations in the critical layers generated by the background wind. Our diagnostic analysis also indicates that the mean flow instability in the upper stratosphere and upper mesosphere might contribute to the amplification of the eastward PWs.</p>L. TangS.-Y. GuX.-K. DouCopernicus PublicationsarticlePhysicsQC1-999ChemistryQD1-999ENAtmospheric Chemistry and Physics, Vol 21, Pp 17495-17512 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Physics QC1-999 Chemistry QD1-999
spellingShingle	Physics QC1-999 Chemistry QD1-999 L. Tang S.-Y. Gu X.-K. Dou Eastward-propagating planetary waves in the polar middle atmosphere
description	<p>According to Modern-Era Retrospective Research Analysis for Research and Applications (MERRA-2) temperature and wind datasets in 2019, this study presents the global variations in the eastward-propagating wavenumber 1 (E1), 2 (E2), 3 (E3) and 4 (E4) planetary waves (PWs) and their diagnostic results in the polar middle atmosphere. We clearly demonstrate the eastward wave modes exist during winter periods with westward background wind in both hemispheres. The maximum wave amplitudes in the Southern Hemisphere (SH) are slightly larger and lie lower than those in the Northern Hemisphere (NH). Moreover, the wave perturbations peak at lower latitudes with smaller amplitudes as the wavenumber increases. The period of the E1 mode varies between 3–5 d in both hemispheres, while the period of the E2 mode is slightly longer in the NH (<span class="inline-formula">∼</span> 48 h) than in the SH (<span class="inline-formula">∼</span> 40 h). The periods of the E3 are <span class="inline-formula">∼</span> 30 h in both the SH and the NH, and the period of E4 is <span class="inline-formula">∼</span> 24 h. Despite the shortening of wave periods with the increase in wavenumber, their mean phase speeds are relatively stable, <span class="inline-formula">∼</span> 53, <span class="inline-formula">∼</span> 58, <span class="inline-formula">∼</span> 55 and <span class="inline-formula">∼</span> 52 m/s at 70<span class="inline-formula"><sup>∘</sup></span> latitudes for E1, E2, E3 and E4, respectively. The eastward PWs occur earlier with increasing zonal wavenumber, which agrees well with the seasonal variations in the critical layers generated by the background wind. Our diagnostic analysis also indicates that the mean flow instability in the upper stratosphere and upper mesosphere might contribute to the amplification of the eastward PWs.</p>
format	article
author	L. Tang S.-Y. Gu X.-K. Dou
author_facet	L. Tang S.-Y. Gu X.-K. Dou
author_sort	L. Tang
title	Eastward-propagating planetary waves in the polar middle atmosphere
title_short	Eastward-propagating planetary waves in the polar middle atmosphere
title_full	Eastward-propagating planetary waves in the polar middle atmosphere
title_fullStr	Eastward-propagating planetary waves in the polar middle atmosphere
title_full_unstemmed	Eastward-propagating planetary waves in the polar middle atmosphere
title_sort	eastward-propagating planetary waves in the polar middle atmosphere
publisher	Copernicus Publications
publishDate	2021
url	https://doaj.org/article/6210ae12c5d74e7f96975d43dc25cfb4
work_keys_str_mv	AT ltang eastwardpropagatingplanetarywavesinthepolarmiddleatmosphere AT sygu eastwardpropagatingplanetarywavesinthepolarmiddleatmosphere AT xkdou eastwardpropagatingplanetarywavesinthepolarmiddleatmosphere
_version_	1718405061473730560

Eastward-propagating planetary waves in the polar middle atmosphere

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