Seasonal variations in lower stratospheric gravity wave energy above the Falkland Islands

Moffat-Griffin, T. ORCID: https://orcid.org/0000-0002-9670-6715; Jarvis, M.J.; Colwell, S.R.; Kavanagh, A.J. ORCID: https://orcid.org/0000-0001-7360-7039; Manney, G.L.; Daffer, W.H.. 2013 Seasonal variations in lower stratospheric gravity wave energy above the Falkland Islands. Journal of Geophysical Research: Atmospheres, 118 (19). 10861-10869. https://doi.org/10.1002/jgrd.50859

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Abstract/Summary

The gravity wave field in the lower stratosphere (between 15 km and 22 km altitude) above Mount Pleasant Airport (51°49’S, 58°26’W), on the Falkland Islands is studied using over 2100 high-resolution radiosonde soundings from 2002-2010. The seasonal variation in vertical direction of propagation shows a small decrease in numbers of upward propagating waves that is related to critical level filtering, however there is a very large increase in numbers of downward propagating waves between July and September; this is attributed to the proximity of the edge of the polar vortex. There is a seasonal variation in gravity wave energy density, with a large peak during the austral autumn equinox; this is markedly different to results in the literature both from Rothera, on the Antarctic Peninsula, and stations on the main Antarctic continent. This seasonal pattern has been shown to be linked to variations in the sources of upward propagating gravity waves. The seasonal variation in gravity wave characteristics above Mount Pleasant Airport seen in our results suggest that the gravity wave field in this region is determined by a combination of different gravity wave sources located above and below the lower stratosphere.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1002/jgrd.50859
Programmes:	BAS Programmes > Polar Science for Planet Earth (2009 - ) > Climate
ISSN:	2169-8961
Additional Keywords:	Middle atmosphere dynamics; Stratospheric dynamics
Date made live:	05 Dec 2012 08:19 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/20674

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