Satellite Observations of Irregularities in the Antarctic Ionosphere

Chapter 1 Introduction. The magnetic field lines that emerge from the polar regions extend to great distances from the earth. The auroral zone closely approximate the boundary between those field lines that are closed within the magnetosphere and those that form the geomagnetic tail. the field lines int he tail may be open or possibly joined with the interplanetary field. this introduces considerable coupling between the polar ionosphere and the distant regions of the earth's atmosphere. High energy charged particles from the sun and disturbances in the magnetosphere, therefore cause large changes in the polar ionosphere, with auroral displays and regions of increased or irregular ionisation. Increasing attention is therefore, being paid to studies of the polar ionosphere to gain some insight into the changes occurring at great heights.