The latitude dependence of OH rotational temperature in the night airglow

Abstract

Rotational temperatures of OH in the night airglow have been measured over the latitude range from 55°N to 85°N during a single night from a jet aircraft flying at 75°W longitude. In March 1963 the rotational temperature was found to decline with increasing latitude from about 200°K to about 160°K; the decline was less pronounced in March 1964. The zenith intensity also fell by nearly a factor of 2 from ∼200 kR to ∼130 kR between 55°N pnd 85°N in 1963; in 1964 the intensity remained more nearly constant at about 200 kR. Such a decrease in rotational temperature at high latitude is in marked contrast to the results of some earlier studies made from ground stations. The temperatures are compared at ∼60°N with rocket measurements made at nearly the same time; the temperatures agree well in the region 80–90 km near the minimum in mesospheric temperature. The decline in rotational temperature at higher latitude is interpreted as indicating a corresponding, and possibly greater, decline in the mesospheric minimum temperature at the high latitudes. A measurement of lower accuracy near the equator (10°N to 20°N) in April 1964 revealed an intensity near 300 kR and a temperature of ∼275°K.