Thermospheric and mesospheric temperatures during geomagnetic storms at 23°S

Abstract

Night-time thermospheric temperatures, T63o, and mesospheric rotational temperatures, T(OH) and T(O 2), have been measured at Cachoeira Paulista (23°S, 45°W, 16°S dip latitude), located in both the equatorial ionospheric anomaly and the South Atlantic Geomagnetic Anomaly, with a Fabry-Perot interferometer and a multi-channel tilting filter-type photometer, respectively. The thermospheric temperatures are obtained from the Doppler line broadening of the OI 630.0 nm emission and the mesospheric rotational temperatures from the OH(9,4) and O 2A(0,1) band emissions. Measurements made during three geomagnetic storms showed that the nocturnal mean values of T 630 during the recovery phase of the storms were lower than those observed during quiet time and from model predictions. Also, the nocturnal mean value of the T 630 soon after the SSC event on 27 June 1992 was higher than the quiet time and model predictions. The observed mesospheric nocturnal mean rotational temperatures, T(O 2) and T(O 2), were unaffected by the storms. A comparison of the night-time observed temperatures T 630, T(OH) and T(O 2) with those calculated using the MSIS-86 model is also presented.