EQUATORIAL MEASUREMENTS OF [OI]5577-A EMISSION OF DAYGLOW WITH A ROCKET PHOTOMETER

Observations of the [OI] 5577 Å emission of the dayglow have been obtained with a rocket photometer from the equatorial launch site at Natal, Brazil. Our observations show that the contribution to the [OI] 5577 Å emission of the dayglow comes from three different ranges of altitudes. The lower layer is around 96 km, with half emission width of about 23 km and peak emission of about 330 photon/cc. This layer contributes about 40 per cent of the total emission, and is similar to the one which contributes most of the [OI] 5577 Å emission of the nightglow. The excitation is of chemical origin. The second layer is in the altitude range of 110-150 km. The probable excitation mechanism is the photodissociation of O2. The third layer is above 150 km. The excitation mechanism is the process of recombination of O2 + and ionospheric electrons, and also the excitation of O2 by photoelectrons. This contributes about 30 per cent to the dayglow emission. © 1969.