Equatorial middle atmospheric temperature response to solar activity, 1971-1982, from spectral analyses
Abstract
Rocket temperature data of the middle atmosphere (20-80 km) over the rocket launching station, THUMBA (8°N, 77°E) during the period 1971-1982 have been used. The auto- and cross-spectral analyses were made with these temperature data and the sunspot number data during the same period, at various altitude levels. The record of both the time series contains 144 continuous monthly data. The Nyqvist frequency was chosen to be 0.5 cycles per month, when the maximum value of the lag factor, m = 14, was chosen. The estimated spectra were subjected to the chi-squared test with 95% confidence level at 20° of freedom. In the sunspot series no quasi-periodic fluctuations were seen over the 11-year period, at the chosen confidence level. On the other hand, quasi-periodic temperature oscillations were observed at 30, 40 and 70 km altitude levels. These are the semi-annual type periodicities at 30 and 40 km and long-periodic events as well as nearly QBOs (quasi-biennial oscillations) at 70 km. Coherence spectra at the various levels have also been analysed. The present study concludes that there is certainly a response of the temperature of the middle atmosphere over THUMBA to long-period events (periods higher than that of the QBO in this study). The analyses were done at the CDC CYBER 170 computer facility at VSSC, Trivandrum.
- Publication:
-
Planetary and Space Science
- Pub Date:
- July 1987
- DOI:
- 10.1016/0032-0633(87)90073-0
- Bibcode:
- 1987P&SS...35..959D
- Keywords:
-
- Atmospheric Temperature;
- Equatorial Atmosphere;
- Middle Atmosphere;
- Solar Activity;
- Solar Terrestrial Interactions;
- Spectrum Analysis;
- Rocket-Borne Instruments;
- Solar Cycles;
- Sunspots;
- Vertical Distribution;
- Geophysics