The Effect of the Interplanetary Magnetic Field Clock Angle and the Latitude Location of the Intense Crustal Magnetic Field on the Ion Escape at Mars: An MHD Simulation Study

Abstract

AbstractIn this paper, using a three‐dimensional multifluid MHD model, we studied the effects of the interplanetary magnetic field (IMF) clock angle and the latitude position of the intense crustal magnetic field (ICMF) on the escape of ions O+, , and at Mars. The main results are as follows: (a) The IMF clock angle affects the ion escape at Mars. When the ICMF is on the dayside, the ion escape rate reaches a maximum at the IMF clock angles close to 60°–90° and a minimum at the IMF clock angles close to 120°–150°, because the ICMF can change the topology of the magnetic field and affect the interaction between the solar wind and Mars. The difference between the maximum and minimum ion escape rates due to the IMF clock angle can reach over 50%. (b) Compared with the −ESW hemisphere, the escape flux of and in the +ESW hemisphere is more significant. However, O+ generally has a larger escape flux in the −ESW hemisphere. The different results in the ±ESW hemispheres might be due to the larger distribution of the hot oxygen corona, which changes the flow pattern of O+. (c) The latitude location of the ICMF can also affect the ion escape. When the ICMF is on the dayside, as the subsolar point varies from 25°S to 25°N, that is, the intense crustal magnetic field position keeps shifting southward, the ion escape rate shows a gradual increase.