MHD Simulations of the Impact of the September 2017 Major Solar Flare and ICME Events on Mars
Abstract
We study the impact of the September 2017 extreme solar flare and interplanetary coronal mass ejection events on Mars using a sophisticated multi-species MHD model. The flare impact is examined by coupling with the Mars Global Ionosphere-Thermosphere Model. A great challenge of the study is that MAVEN was mostly inside the Martian bow shock during the events, and thus no direct solar wind measurement was available. To carry out reasonable simulations, we first simulate the events using steady-state assumptions with rough solar wind estimates. Although these simplistic time-stationary runs are able to capture the general features observed by MAVEN, they cannot represent the details of the large perturbations associated with the events. To describe the time variation during the space weather events, we estimate upstream solar wind conditions by fitting steady-state MHD model results to MAVEN observations in the sheath region. The obtained solar wind proxies are then used to drive a time-dependent MHD simulation. It is found that the data-model comparison is greatly improved, especially in the magnetosheath region. We are able to reproduce many detailed structures observed by MAVEN during the period despite the fact that no direct measurement of the solar wind is available. This model-data agreement confirms the validity of the derived upstream solar wind conditions. Using the time-dependent results, we examine in detail the impact of the events on the Martian system, including three plasma boundaries (Bow Shock, induced magnetosphere and ion composition boundaries) and ion loss rates. It is found that these plasma boundaries vary dramatically during the ICME and total planetary ion loss rates are enhanced by more than an order of magnitude.
- Publication:
-
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018
- Bibcode:
- 2018cosp...42E2103M