Abstract
Abstract. The nightglow OH(9, 4) and O2 atmospheric (0,1) band emission intensities and their rotational temperatures T(OH) and T(O2), respectively, observed at Cachoeira Paulista (23°S, 45°W), Brazil, during the period from October 1989 to December 1990, have been analyzed to study the nighttime mesospheric energy loss rates through the radiations from the vibrationally excited OH* and electronically excited O2* bands. The total emission rates of the OH Meinel bands, O2 atmospheric (0,0) and O2 infrared atmospheric (1Δg) bands were calculated using reported data for the relative band intensities I(ν'',ν')/I(9,4), IO2A(0,0)/IO2A(0,1) and IO2(1Δg)/IO2A(0,1). It was found that there is a minimum in equivalent energy loss rate by the OH* Meinel bands during December/January (equivalent energy loss rate of 0.39K/day*, where day* means averaged over the night) and maximum in equivalent energy loss rate during September (equivalent energy loss rate of 0.98K/day*). Energy loss rate by the O2* radiation, on the other hand, is weaker than that by the OH* Meinel bands, showing equivalent energy loss rates of 0.12K/day* and 0.22K/day* during January and September, respectively.
Highlights
Energy loss rate by the O2 radiation, on the other hand, is weaker than that by the OH Meinel bands, showing equivalent energy loss rates of 0:12 K/day and 0:22 K/day during January and Several investigators have studied the propagation of waves in the mesosphere using ground-based observations of mesospheric nightglow emissions, e.g., NaD 589.3 nm, OH Meinel bands, O2 atmospheric (0,1) band and OI 557.7 nm (Krassovsky, 1972; Misawa and Takeuchi, 1977; Takahashi et al, 1985; Taylor et al, 1987; Myrabù and Harang, 1988; Fagundes et al, 1995)
The seasonal variations of the monthly means of the intensities and rotational temperatures presented in this study agree with some previous works by Takahashi et al (1977; 1984; 1986) from the same location
Our present study shows that the monthly equivalent energy loss rate variations by the OH Meinel bands is
Summary
Several investigators have studied the propagation of waves in the mesosphere (tides and gravity waves) using ground-based observations of mesospheric nightglow emissions, e.g., NaD 589.3 nm, OH Meinel bands, O2 atmospheric (0,1) band and OI 557.7 nm (Krassovsky, 1972; Misawa and Takeuchi, 1977; Takahashi et al., 1985; Taylor et al, 1987; Myrabù and Harang, 1988; Fagundes et al, 1995). Energy loss through optical radiations of the vibrationally excited OH m0 ; m00 and electronically excited O2 airglow are important channels of the heat budget in the mesospheric region. R. Fagundes et al.: Mesopheric energy loss rates by OH and O2 emissions at 23°S to describe the time variation of the temperature in the mesosphere, all kinds of energy, such as chemical potential, kinetic, thermal, radiant, etc., should be included. Fagundes et al.: Mesopheric energy loss rates by OH and O2 emissions at 23°S to describe the time variation of the temperature in the mesosphere, all kinds of energy, such as chemical potential, kinetic, thermal, radiant, etc., should be included It should consider sources and sinks of energy, i.e., vertical and horizontal transports and conduction, and energy transformation to and from kinetic, internal and chemical potential. In this work we have calculated and discussed important features of the reduction of chemical heating by airglow radiations in the mesospheric region at 23 S
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