Two-day Planetary Wave Impact on Austral Polar Mesopause Temperatures: as Revealed by a January Diminution in PMSE above Davis, Antarctica
Abstract
A new characteristic of the austral summer polar mesopause as revealed by ground MST radar charged ice- aerosol echoes and satellite MLS temperature is reported, that is plausibly linked to the low-latitude easterly wind jet. Four consecutive seasons of polar mesosphere summer echoes (PMSE) and mesosphere temperature observations above Davis, Antarctica (geographic: 68.6°S; 78.0°N) exhibit an annual mid-January diminution in PMSE occurrence rate that is correlated with a simultaneous mesopause warming by several degrees. Interestingly, the corresponding mesosphere meridional wind field changes from equatorward to a poleward flow at these times. Although displaying some inter-annual variation in the peak onset time, the mid-January mesopause warming correlates with the peak in the line-of-sight meridional wind and temperature enhancements (both poleward and in altitude) associated with the low-latitude 2-day planetary wave (PW). Periodogram analyses of PMSE and Aura MLS temperatures show the dominance of 5- day PWs throughout the austral summer coupled with pronounced 2-day PWs evident from early January to mid-February. Zonal spectral analyses of Aura MLS temperature records reveal the high-latitude 2-day PWs have zonal wavenumber (s) with both westward (s = -2, -3) and eastward (s = 2, 3) spectral features consistent with the periodogram results. Our polar observations support the evolution of a myriad of prodigy PWs spawned from the westward 2-day PW (s = -3) activity, originating from the low-latitude easterly jet, albeit not previously linked to the reported mid-January diminution of PMSE at southern latitudes.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFMSA33C..07M
- Keywords:
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- 3309 Climatology (1616;
- 1620;
- 3305;
- 4215;
- 8408);
- 3311 Clouds and aerosols;
- 3332 Mesospheric dynamics;
- 3334 Middle atmosphere dynamics (0341;
- 0342);
- 3389 Tides and planetary waves