On Martian nitrogen dayglow emission observed by SPICAM UV spectrograph/Mars Express

Abstract

SPICAM UV spectrograph on board Mars Express has reported, for the first time, the identification of the N2 VK (0,5) and (0,6) band emissions in the Martian dayglow. The derived exospheric temperature of the N2 species in the upper Martian atmosphere is equal to 190 ± 51 K for areocentric longitudes between 100° and 171° and equal to 257 ± 71 K for areocentric longitudes between 287° and 321°. These temperatures are in agreement with the ones deduced from the analysis of the 289 nm emission associated with the CO2 major Martian atmospheric species. The intensity of the N2 VK (0,6) band is found to be ∼3 times smaller than the calculated intensity of Fox and Dalgarno (1979) which is reasonable when considering the uncertainties in the parameters used by Fox and Dalgarno (1979) and the uncertainties on SPICAM UVS observations.