Mid-latitude summer response of the middle atmosphere to short-term solar UV changes
Temperature and wind data obtained with Rayleigh lidar since 1979 and Russian rockets since 1964 are analyzed to deduce the summer response of the middle atmosphere to short-term solar UV changes. The equivalent width of the 1083 nm He I line is used as a proxy to monitor the short-term UV flux...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
1995-06-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/13/641/1995/angeo-13-641-1995.pdf |
| Summary: | Temperature and wind data obtained with
Rayleigh lidar since 1979 and Russian rockets since 1964 are analyzed to deduce
the summer response of the middle atmosphere to short-term solar UV changes. The
equivalent width of the 1083 nm He I line is used as a proxy to monitor the
short-term UV flux changes. Spectral analyses are performed on 108-day windows
to extract the 27-day component from temperature, wind and solar data sets.
Linear regressions between these spectral harmonics show some significant
correlations around 45 km at mid-latitudes. For large 27-day solar cycles,
amplitudes of 2 K and 6 m s<sup>-1</sup> are calculated for temperature data
series over the south of France (44°N), and on wind data series over Volgograd
(49°N), respectively. Cross-spectrum analyses have indicated correlations
between these atmospheric parameters and the solar proxy with a phase lag of
less than 2 days. These statistically correlative results, which provide good
qualitative agreement with numerical simulations, are both obtained at
mid-latitude. However, the observed amplitudes are larger than expected, with
numerical models suggesting that dynamical processes such as equatorial or
gravity waves may be responsible. |
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| ISSN: | 0992-7689 1432-0576 |