Seasonal variations of the Na and Fe layers at the South Pole and their implications for the chemistry and general circulation of the polar mesosphere

Gardner, Chester S.; Plane, John M.C.; Pan, Weilin; Vondrak, Tomas; Murray, Benjamin J.; Chu, Xinzhao

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https://hdl.handle.net/2142/72646 Copy

Description

Title

Seasonal variations of the Na and Fe layers at the South Pole and their implications for the chemistry and general circulation of the polar mesosphere

Author(s)

• Gardner, Chester S.
• Plane, John M.C.
• Pan, Weilin
• Vondrak, Tomas
• Murray, Benjamin J.
• Chu, Xinzhao

Issue Date

2005

Keyword(s)

• South Pole
• Polar mesosphere
• Meteorology and Atmospheric Dynamics

Abstract

Lidar observations, conducted at the South Pole by University of Illinois researchers, are used to characterize the seasonal variations of mesospheric Na and Fe above the site. The annual mean layer abundances are virtually identical to midlatitude values, and the mean centroid height is just 100 m higher for Na and 450 m higher for Fe compared with 40 N. The most striking feature of the metal profiles is the almost complete absence of Na and Fe below 90 km during midsummer. This leads to summertime layers with significantly higher peaks, narrower widths, and smaller abundances than are observed at lower latitudes. The measurements are compared with detailed chemical models of these species that were developed at the University of East Anglia. The models accurately reproduce most features of these observations and demonstrate the importance of rapid uptake of the metallic species on the surfaces of polar mesospheric clouds and meteoric smoke particles. The models show that vertical downwelling in winter, associated with the meridional circulation system, must be less than about 1 cm s 1 in the upper mesosphere in order to avoid displacing the minor constituents O, H, and the metal layers too far below 85 km. They also show that an additional source of gas-phase metallic species, that is comparable to the meteoric input, is required during winter to correctly model the Na and Fe abundances. This source appears to arise from the wintertime convergence of the meridional flow over the South Pole.

Publisher

American Geophysical Union

Type of Resource

text

Language

en

Permalink

http://hdl.handle.net/2142/72646

DOI

https://doi.org/10.1029/2004JD005670

Copyright and License Information

Copyright 2005 American Geophysical Union

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