Stratomesospheric CO measured by a ground-based Fourier Transform Spectrometer over Poker Flat, Alaska: Comparisons with Odin/SMR and a 2-D model

• The interseasonal variability of stratomesospheric CO is reported from Poker Flat, Alaska, using spectra from a ground-based Fourier Transform Spectrometer (gb-FTS) for the time period from 2000 to 2004. The CO spectra were analyzed using an optimal estimation technique that separates the tropospheric and stratospheric/mesospheric components into partial columns. The distribution of CO in the polar winter is such that the gb-FTS retrieved partial column is weighted to the mesosphere. The gb-FTS data are compared with measurements of partial column CO from the Sub-Millimeter Radiometer on board the Odin satellite and shown to be in very good agreement despite the relatively small sample size. The mean difference of the two data sets indicates a small positive bias (7.6 +/- 6%) in favor of the Odin data, with a correlation coefficient, r(2) = 0.91. The gb-FTS data indicate that there is a strong seasonal dependence of the CO partial column that is consistent with known winter polar thermospheric descent of CO enriched air. Year-to-year variability is explained in terms of mesospheric wind dynamics, which show 2004 and components of 2002 were affected by earlier than expected breakdown (30 +/- 13 d) of the winter polar circulation compared with 2000 to 2003. Finally, the measured CO data is compared with a 2-D chemical transport model that gives support to the idea that springtime polar mesospheric CO is driven by meridional winds.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Meteorologi och atmosfärforskning (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Meteorology and Atmospheric Sciences (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences (hsv//eng)

Nyckelord

Fourier Transform Infrared Spectroscopy

Carbon monoxide

Mesosphere

Odin Sub-Millimetre Radiometer

Atmospheric circulation

Stratosphere

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