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Gravity Wave Variability in the Arctic Mesosphere in Relation with the Stratospheric Polar Vortex
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  • Subir Mandal,
  • Tracy Moffat-Griffin,
  • Corwin James Wright,
  • Pierre-Dominique Pautet,
  • Michael J. Taylor,
  • Takuji Nakamura
Subir Mandal
British Antarctic Survey

Corresponding Author:[email protected]

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Tracy Moffat-Griffin
British Antarctic Survey
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Corwin James Wright
University of Bath
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Pierre-Dominique Pautet
Utah State Uiversity
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Michael J. Taylor
Utah State University
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Takuji Nakamura
National Institute of Polar Research
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Abstract

We investigated the variability of short-period (<1 hour) atmospheric gravity waves (AGWs) in the high-latitude mesosphere-lower-thermosphere/ionosphere (MLTI) region using OH (3,1) band emission data from the Advanced Mesospheric Temperature Mapper (AMTM) at the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) in Norway. These OH intensity maps from January 2014, 2015, and 2016 were analysed to characterise AGW activity at these altitudes. We derived phase velocity spectra of AGWs by applying the Matsuda-transform to the OH intensity maps and calculated spectral power across different phase speed ranges and propagation directions to study the day-to-day and intraday variability of AGWs. Our results reveal significant differences in AGW activity between these years, with 2015 exhibiting lower spectral power and less variability compared to 2014 and 2016. The vertical propagation efficiency of AGWs was estimated using principles of critical-level filtering, incorporating winds from the ERA5 dataset for altitudes between 0–50 km. The relatively lower AGW activity and spectral power observed in the MLTI region in 2015 were associated with higher Arctic Oscillation (AO) index values, suggesting gravity wave filtering by eastward winds in the upper stratosphere. In contrast, lower AO index values in 2014 and 2016 indicated minimal filtering, leading to more diverse spectra of AGWs observed in the OH images. These findings highlight the strong influence of stratospheric wind structures on AGW variability in the high-latitude MLTI region during winter.
04 Oct 2024Submitted to ESS Open Archive
07 Oct 2024Published in ESS Open Archive