Structure, Variability, and Mean-Flow Interactions of the January 2015 Quasi-2-Day Wave at Middle and High Southern Latitudes

David C. Fritts, Hiroyuki Iimura, Diego Janches, Ruth S. Lieberman, Dennis M. Riggin, Nicholas J. Mitchell, Robert A. Vincent, Iain M. Reid, Damian J. Murphy, Masaki Tsutsumi, Andrew J. Kavanagh, Paulo P. Batista, Wayne K. Hocking

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Abstract

The structure, variability, and mean-flow interactions of the quasi-2-day wave (Q2DW) in the mesosphere and lower thermosphere during January 2015 were studied employing meteor and medium-frequency radar winds at eight sites from 23°S to 76°S and Microwave Limb Sounder (MLS) temperature and geopotential height measurements from 30°S to 80°S. The event had a duration of ~20–25 days, dominant periods of ~44–52 hr, temperature amplitudes as large as ~16 K, and zonal and meridional wind amplitudes as high as ~40 and 80 m/s, respectively, at middle and lower latitudes. MLS measurements enabled definition of balance winds that agreed well with radar wind amplitudes and phases at middle latitudes where amplitudes were large and quantification of the various Q2DW modes contributing to the full wave field. The Q2DW event was composed primarily of the westward zonal wavenumber 3 (W3) mode but also had measurable amplitudes in other westward modes W1, W2, and W4; eastward modes E1 and E2; and stationary mode S0. Of the secondary modes, W1, W2, and E2 had the larger amplitudes. Inferred MLS balance winds enabled estimates of the Eliassen-Palm fluxes for each mode, and cumulative zonal accelerations that were found to be in reasonable agreement with radar estimates from ~35°S to 70°S at the lower altitudes at which radar winds were available.

Original languageEnglish
Pages (from-to)5981-6008
Number of pages28
JournalJournal of Geophysical Research: Atmospheres
Volume124
Issue number12
Early online date2 May 2019
DOIs
Publication statusPublished - 27 Jun 2019

Keywords

  • planetary-wave Eliassen-Palm fluxes
  • planetary-wave/mean-flow interactions
  • quasi-2-day wave
  • quasi-2-day wave transience

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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