Magnetopause expansions for quasi-radial interplanetary magnetic field: THEMIS and Geotail observations
2010
Abstract
We report Themis and Geotail observations of prolonged magnetopause expansions during long-lasting intervals of quasi-radial interplanetary magnetic field and nearly constant solar wind dynamic pressure. The expansions were global: The magnetopause was located more than 3 RE and 7 RE outside its nominal dayside and magnetotail locations, respectively.
The equilibrium position was affected by geomagnetic activity. The magnetopause expansions result from significant decreases in the total pressure of the high beta magnetosheath, which we term the low-pressure magnetosheath mode.