Solar control of CO2^+ultraviolet doublet emission on Mars

作者：ZiChuan Li,Jun Cui,Jing Li,XiaoShu Wu,JiaHao Zhong,FaYu Jiang

摘要：The CO2^+;ultraviolet doublet(UVD)emission near 289 nm is an important feature of dayside airglow emission from planetaryupper atmospheres.In this study,we analyzed the brightness profiles of CO2^+;UVDemission on Mars by using the extensive observationsmade by the lmaging Ultraviolet Spectrograph on board the recent Mars Atmosphere and Volatle Evolution spacecraft.Strong solar cycleand solar zenith angle variations in peak emission intensity and altitude were revealed by the data:(1)Both the peak intensity and altitude increase with increasing solar activity,and(2)the peak intensity decreases,whereas the peak altitude increases,with increasingsolar zenith angle.These observations can be favorably interpreted by the solar-driven scenario combined with the fact that photoionization and photoelectron impact ionization are the two most important processes responsible for the production of excited-state cotand consequently the intensity of CO2^+;UVDemission.Despite this,we propose that an extra driver,presumably related to thecomplicated variation in the background atmosphere,such as the occurrence of globaldust storms is required to fuly interpret theobservations.In general,our analysis suggests that the CO2^+;UVD emission is a useful diagnostic of the variability of the dayside Martianatmosphere under the influences of both internal and external drivers.

发文机构：National Astronomical Observatories School of Astronomy and Space Sciences Planetary Environmental and Astrobiological Research Laboratory（PEARL） Center for Excellence in Comparative Planetology Lunar and Planetary Laboratory

关键词：MARSdayglowCO2^+MAVEN

分类号： P35[天文地球—空间物理学]