Quantifying the role of orographic gravity waves on polar st

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TitleQuantifying the role of orographic gravity waves on polar stratospheric cloud occurrence in the Antarctic and the ArcticAbstractThe proportion of polar stratospheric clouds due to orographic gravity wave (OGW) forcing is quantified during four Antarctic (2007-2010) and four Arctic (2006/2007 to 2009/2010) winter seasons. OGW-active days are defined as those days above major polar mountain ranges which have wave-ice polar stratospheric clouds (PSCs), tropospheric wind conditions appropriate for orographic wave generation and propagation, and stratospheric temperatures below the frost point: 37% of Antarctic days and 12% of Arctic days are OGW-active. Regions downstream of these mountain ranges are defined using a forward-trajectory model which follows particle movement from ridge lines for 24 h periods. In both hemispheres in these mountain regions, more than 75% of H<inf>2</inf>O ice PSCs and around 50 percent of a high number density liquid-nitric acid trihydrate mixture class (Mix 2-enh) are attributed to OGW activity, with the balances due to non-orographic formation. For the whole Arctic (equatorward of 82 deg), 25% of Mix 2-enh and 54% of H<inf>2</inf>O ice PSCs are attributed to OGWs, while for the whole Antarctic, 7 percent of Mix 2-enh and 13 percent of H<inf>2</inf>O ice PSCs are attributed to OGWs. For all types of PSC, 5% in the whole Antarctic and 12% in the whole Arctic are attributed to OGW forcing. While gravity waves play a role in PSC formation in the Antarctic, overall it is minor compared with other forcing sources. However, in the synoptically warmer Arctic, much larger proportions of PSCs are due to OGW activity. Key Points PSCs due to OGWs using satellite and trajectory model data Role of OGW in formation of PSCs more important in warmer Arctic The polar-cap total PSCs due to OGW activity is lower in the Antarctic. Copyright2013. American Geophysical Union. All Rights Reserved.AcknowledgementsThe CALIPSO CALIOP v3.01 Level 1BProfile data products were obtained through the NASA Langley Atmo-spheric Science Data Center (ASDC). The COSMIC version 2.0 dry tem-perature data were obtained from the COSMIC Data Analysis and ArchiveCenter (CDAAC). Aura MLS data (v3.3) used in this study were acquired as part of the NASAÅ› Earth-Sun System Division and archived and distributed by the Goddard Earth Sciences (GES) Data and Information Services Center (DISC) Distributed Active Archive Center (DAAC). This research was conducted for projects 737, 3140, and 4012 of the Australian Antarctic program and partially supported by Antarctica New Zealand. This work was partially supported by the Royal Society of New Zealand Marsden Fund project Evaluating the Impact of Excess Ionization on the Atmosphere. We thank the three anonymous reviewers for their constructive comments, which allowed us to improve an earlier version of the manuscript.

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1st AuthorAlexander, S.AuthorAlexander, S.Klekociuk, A.McDonald, A.Pitts, M.Year2013JournalJournal of Geophysical Research AtmospheresVolume118Number20Pages11493-11507DOI10.1002/2013JD020122URLhttps://www.scopus.com/inward/recor.....6c046d7e268c07aaa9b421e32KeywordsGravity wavesLandformsWind, Mountain regionsOrographic gravity wavesParticle movementPolar stratospheric cloudsStratospheric temperatureTrajectory modelingTropospheric windsWave generation and propagation, Ice, atmospheric forcinggravity wavemountain regionorographic effectpolar regionpolar stratospheric cloudsatellite imagerysynoptic meteorologytropospherewinter, Antarctica, rank5Author Keywordsgravity wavespolar stratospheric clouds

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TypeArticleCitationAlexander, S., Klekociuk, A., McDonald, A. and Pitts, M. (2013). Quantifying the role of orographic gravity waves on polar stratospheric cloud occurrence in the Antarctic and the Arctic. Journal of Geophysical Research Atmospheres, 118(20): 11493-11507 IdentifierAlexander2013Relevancerank5