Control ofMars global atmospheric loss by the continuous rotation of the crustalmagnetic field: A time-dependent MHD study

摘要

We present a time-dependent MHD study of the controlling effects of the Mars crustal field on atmospheric escape. We calculate globally integrated planetary ion loss rates under quiet solar conditions considering the continuous rotation of crustal anomalies with the planet. It is found that the rotating crustal field plays an important role in controlling atmospheric escape. Significant time variation of ～20% and ～50% is observed during the entire rotation period for O~+ and for O_2~+ and CO_2~+, respectively. The control is exerted mainly through two processes. First, the crustal magnetic pressure over the subsolar regime controls solar wind penetration and mass loading and therefore the escaping planetary ion source. There is a strong negative correlation between the magnetic pressure and ion loss, with a time lag of