Distribution of O^(+)and O_(2)^(+) fluxes and their escape rates in the near-Mars magnetotail:A survey of MAVEN observations  

作　　者：HengLe Du Xing Cao BinBin Ni Song Fu Xin Ma XiaoTong Yun MinYi Long Qiong Luo 

机构地区：[1]Department of Space Physics,School of Electronic Information,Wuhan University,Wuhan 430072,China [2]Chinese Academy of Sciences,Center for Excellence in Comparative Planetology,Hefei 230026,China

出　　处：《Earth and Planetary Physics》2022年第6期536-545,共10页地球与行星物理（英文版）

基　　金：supported by the National Natural Science Foundation of China (grants 42025404, 42188101, 41904144, and 41674163);the preresearch projects on Civil Aerospace Technologies (grants D020303, D020104, and D020308);funded by the China National Space Administration;the B-type Strategic Priority Program of the Chinese Academy of Sciences (grant XDB41000000);the Fundamental Research Funds for the Central Universities (grants 2042021kf1045 and 2042021kf1056)

摘　　要：Tailward ion outflows in the Martian-induced magnetotail are known to be one of the major channels for Martian atmospheric escape.On the basis of nearly 6.5 years of observations from the Mars Atmosphere and Volatile EvolutioN(MAVEN)mission,we investigate the statistical distribution of tailward and Marsward fluxes of heavy ions(i.e.,O^(+),and O_(2)^(+))in the near-Mars magnetotail and explore their characteristic responses to the corotating interaction region(CIR),solar wind dynamic pressure,and local magnetic field intensity.Our results show that the tailward fluxes of oxygen ions and molecular oxygen ions in the magnetotail are significantly greater than their Marsward fluxes and that the tailward flux of molecular oxygen ions is generally larger than that of oxygen ions.Furthermore,the tailward ion flux distribution exhibits dependence on the CIR,solar wind dynamic pressure,and local magnetic field strength in a manner stronger than the Marsward ion flux distribution.According to the distribution of tailward ion fluxes,we calculate the corresponding escape rates of heavy ions and show that when the CIR occurs,the total escape rates of oxygen ions and molecular oxygen ions increase by a factor of~2 and~1.2,respectively.We also find that the escape rates of heavy ions increase with the enhancement of solar wind dynamic pressure,whereas the overall effect of the local magnetic field is relatively weak.Our study has important implications for improved understanding of the underlying mechanisms responsible for the Martian atmospheric escape and the evolution of the Martian atmospheric climate.

关 键 词：Martian-induced magnetotail atmospheric heavy ion outflow corotating interaction region escape rate 

分 类 号：P185.3[天文地球—天文学]