The configuration of the high altitude, high latitude magnetosphere

The solar wind interaction with the Earth distorts the Earth's intrinsic dipolar magnetic field forming various plasma boundaries and current layers. The magnetosphere is the region of influence of the Earth's magnetic field. It is bounded on the top by the magnetosphere and on the bottom by the ionosphere. The high altitude, high-latitude magnetosphere is of particular interest because there have been few spacecraft surveying this region so the properties of this region are less understood than those at low-altitude and low-latitude. This dissertation studies the characteristics of this high-latitude, high-altitude magnetosphere including the magnetopause, polar cusp and the field-aligned currents. Its main purpose is to understand how the polar cusp is formed and what parameters and processes control its properties.; Hawkeye magnetic field data is used to identify the magnetopause crossings near the polar cusp and their positions relative to the polar cusp funnel. The shape of the magnetopause in this region is obtained by fitting the data points to a conic section. We find that it is different from that at low latitudes in that the extrapolated subsolar positions of the magnetopause are inside those obtained at low latitudes and the eccentricity is greater at high latitudes than that at low latitudes. The statistical location of the magnetic field bifurcation point is swept back than predicted by empirical magnetic field model.; The statistical characteristics of the polar cusp at mid-altitudes from about 5–7 Re are found by studying the polar magnetic and plasma data. The location of the cusp is compared with that from low altitude observations. The cusp extends a wider range of the magnetic local time at high altitudes than at low altitudes. The position and extension of the cusp are affected by the dipole tilt angle, solar wind dynamic pressure and the By and Bz components of the interplanetary magnetic field. The diamagnetic pressure in the cusp is a function of the solar wind dynamic pressure and the normal direction of the magnetopause near the cusp region.; The large-scale region 1 field-aligned current near the cusp region is studied using the polar magnetic field data. The local time and IMF By distribution of this cusp region 1 current shows that for positive IMF By, the downward current on the dawnside extends across noon into the early afternoon side and vice versa for negative IMF By.