Hydromagnetic waves in the magnetosphere

Abstract

The study of hydromagnetic waves in the magnetosphere has seen some notable advances over the last four years. We owe a large debt to the IMS observational programs both in space and on the ground. These programs have produced extremely valuable data sets which should be worked on for many years to come.The improvement in instrumentation has been a major factor in observational work. The new generation of spacecraft are exemplified by the ISEE and GEOS missions, both of which have novel aspects. Both missions have played a large part in helping us understand how important heavy ions are in the propagation of hydromagnetic waves of all frequencies. The dual spacecraft, ISEE 1 and ISEE 2, are helping to unravel the spatial structure of these waves in space, while both missions are providing the first measurements of electric field oscillations associated with hydromagnetic waves. The ionospheric electric field measurements made by the STARE radar system have introduced a new dimension to the field, and help provide a link between ground based and spacecraft measurements. Several ground based magnetometer networks were either introduced or expanded, largely as a result of the IMS.