Massive multi-mission statistical study and analytical modeling of the
Earth’s magnetopause: 2 - Shape and location
Abstract
The Earth magnetopause is the boundary between the magnetosphere and the
shocked solar wind. Its location and shape are primarily determined by
the properties of the solar wind and interplanetary magnetic field (IMF)
but the nature of the control parameters and to what extent they impact
the stand-off distance, the flaring, and the symmetries, on the dayside
and night side, is still not well known. We present a large statistical
study of the magnetopause location and shape based a multi-mission
magnetopause database, cumulating 17 230 crossings on 17 different
spacecraft, from the dayside to lunar nightside distances. The IMF clock
angle itself (all amplitudes combined) is fount not to impact the
stand-off distance, nor does the cone angle. However, the magnetopause
is found to move Earthward as the IMF gets stronger and more southward.
All upstream conditions combined, it is found that the function used at
the root of several analytical models still holds at lunar distances.
The meridional flaring is found to depend on the seasonal tilt
conditions, being larger in the summer hemisphere. The flaring is also
found to depend on the IMF clock angle. Meridional flaring increases as
the IMF turns south and is then larger than the equatorial flaring. The
equatorial flaring barely changes or weakly increases as the IMF turns
northward, and is larger than the meridional flaring for northward
conditions. The study pave the way for the elaboration of a new
analytical empirical expression magnetopause surface model.