Seminars

Lecturer: Naoki Terada (Tohoku)
Date: 2012-09-13 10:30
Place: Aniara

Modeling solar wind interaction with Venus and Mars: Ionospheric flow pattern, tail field structure, and time variation of ionosphere-exosphere coupling

Dr. Naoki Terada
Tohoku Univ.
Japan

Abstract
Three-dimensional ionospheric flow pattern and field structures as well as escape of cold ions from the ionospheres of Venus and Mars are investigated using a global magnetohydrodynamic (MHD) model. Our MHD model shows a complex flow pattern of the ionospheric plasma, forming large-scale four vortex structures on the nightside and escape channels through the magnetotail region. The magnetic field lines in the near-tail region also exhibit a complex structure, where a twisted field line is connected to that in the opposite hemisphere. We find that this tail field structure is produced by a series of magnetic reconnections. Our MHD model is also coupled with a time-dependent exosphere model, which was developed by K. Terada, to investigate the dynamical variations of nonthermal escape rate in response to variations in solar wind conditions. We show that an increase in the solar wind dynamic pressure results in the temporal enhancement of hot oxygen escape rate by a factor of 2 to 4 compared with that of the steady state case. The hot oxygen density is found to be less sensitive to the variation of the solar wind dynamic pressure than is the escape rate.

Created 2012-08-31 09:31:41 by Mats Holmström
Last changed 2012-09-10 20:17:22 by Mats Holmström