The Use of Ground Distributed Magnetometer Arrays in ULF and EMIC Wave Studies

Close-spaced magnetometer arrays located at high and low latitudes may be used to measure the phase and propagation characteristics of ultra-low frequency (ULF) and electromagnetic ion cyclotron (EMIC) waves in the magnetosphere. ULF wave cross-phase techniques can be used to determine the mass-loaded ion density along closed field lines in the magnetosphere and locate the open-closed field line boundary at high latitudes. Phase and polarisation techniques may also be used to determine the exit point of EMIC waves propagating down field lines into the ionosphere. Examples will be presented that illustrate some important future applications that may be utilized by reasonably close-spaced ground magnetometer arrays.