Abstract
Abstract. More than 3 years of airglow observations with a Spectral Airglow Temperature Imager (SATI) installed at the Sierra Nevada Observatory (37.06°N, 3.38°W) at 2900m height have been analyzed. Values of the column emission rate and vertically averaged temperature of the O2 atmospheric (0–1) band and of the OH Meinel (6–2) band from 1998 to 2002 have been presented. From these observations a clear seasonal variation of both emission rates and rotational temperatures is inferred at this latitude. It is found that the annual variation of the temperatures is larger than the semi-annual variation, while for the emission rates the amplitudes are comparable. Key words. Atmospheric composition and structure (airglow and aurora; pressure density and temperature; instruments and techniques)
Highlights
Airglow emissions give important information on the dynamics and chemistry of the upper atmosphere
The values of the OH rotational temperatures and emission rates that we report in this paper were obtained using the earlier A(Q) coefficients, but we have applied the correction used by Pendleton and Taylor (2002), before finding a most appropriate correction, to estimate rotational temperatures from the OH(6–2) Meinel band
A clear annual variation is found in temperatures and an annual variation, together with a semiannual variation of similar magnitude, is found in the emission rates
Summary
Airglow emissions give important information on the dynamics and chemistry of the upper atmosphere. After the discovery of the vibration-rotation of the OH Meinel system in the night airglow by Meinel (1950a), a great number of works have been devoted to the observation of the temporal variations of the emission rates and rotational temperatures of the OH Meinel bands Shefov, 1969, 1971a; Takahashi et al, 1977; Mulligan et al, 1995) These measurements have shown a great variability for the different OH Meinel bands. Rotational temperatures from the OH Meinel bands have been used as indicators of atmospheric temperature at 87 km height. Rocket and satellite measurements have shown that the peak of maximum emission rate of the O2 atmospheric emission is placed at about 95 km (e.g. Witt et al, 1979, 1984; Greer et al, 1986). Rotational temperatures from the O2(0–1) atmospheric band are good indicators of the atmospheric temperature at around 95 km height
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