Mesospheric energy loss rates by OH and O2 emissions at 23°S

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 O 2 bands. The total emission rates of the OH Meinel bands, O2 atmospheric (0,0) and O2 infrared atmospheric …Dg† bands were calculated using reported data for the relative band intensities I…m00;m0†=I…9;4†; IO2A…0;0†=IO2A…0;1† and IO2…1Dg†=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 O 2 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.