Mid-latitude summer response of the middle atmosphere to short-term solar UV changes |
| |
Authors: | P Keckhut |
| |
Institution: | (1) Service d’Aéronomie du CNRS, BP3, 91371 Verrières Le Buisson, France |
| |
Abstract: | 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−1 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. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|