Atmospheric heating in the auroral zones: A preliminary analysis of the atmospheric drag of the Injun 3 satellite

Injun 3 is a near-spherical object in an orbit with eccentricity 0.16, inclination 70.4°, and a mean perigee height of 250 km. An analysis of the drag during the first half-year after launching has revealed (1) that on geomagnetically quiet days the upper-atmosphere temperature in the auroral zones is essentially the same as at the equator, and (2) that the heating accompanying geomagnetic perturbations in the auroral zones is 4 or 5 times greater than the heating experienced during these perturbations in low latitudes. In addition, the present analysis gives a calibration of atmospheric models at the critical height of 250 km. The amplitude of the diurnal temperature oscillation is found to be smaller than was expected, but the cause of the discrepancy may lie in part with the atmospheric model.