CO Cameron band and CO 2 + UV doublet emissions in the dayglow of Venus: Role of CO in the Cameron band production

摘要

The present study deals with the model calculations of CO Cameron band and CO2+ ultraviolet doublet emissions in the dayglow of Venus. The overhead and limb intensities of CO Cameron band and CO2+ UV doublet emissions are calculated for low, moderate, and high solar activity conditions. Using updated cross sections, the impact of different e-CO cross sections for Cameron band production is estimated. The electron impact on CO is the major source mechanism of Cameron band, followed by electron and photon impact dissociation of CO _2. The overhead intensities of CO Cameron band and CO2+UV doublet emissions are about a factor of 2 higher in solar maximum than those in solar minimum condition. The effect of solar EUV flux models on the emission intensity is ～30-40% in solar minimum condition and ～2-10% in solar maximum condition. At the altitude of emission peak (～135 km), the model predicted limb intensity of CO Cameron band and CO2+ UV doublet emissions in moderate (F10.7=130) solar activity condition is about 2400 and 300 kR, respectively, which is in agreement with the very recently published SPICAV/Venus Express observation. The model limb intensity profiles of CO Cameron band and CO2+UV doublet are compared with SPICAV observation. We also calculated intensities of N2Vegard-Kaplan UV bands and O I 2972 ? emissions during moderate and high solar activity conditions. Key Points Detailed model calculation of CO Cameoron and CO2+ UV doublet emissions on Venus Present study shows the importance of e-CO process in Cameron band production Predictions are made for possible VEX UV observation in solar moderate condition