Gw. Hoogeveen et Ar. Jacobson, IMPROVED ANALYSIS OF PLASMASPHERE MOTION USING THE VLA RADIO INTERFEROMETER, Annales geophysicae, 15(2), 1997, pp. 236-245
Observations using the very large array (VLA) radio interferometer dur
ing the past five years have enabled the discovery of a new type of pl
asmasphere disturbance, the magnetic eastward-directed wave. Previous
work indicated these disturbances were likely frozen to the geomagneti
c field as determined from their azimuth distributions. This work prov
ides a method to explain more accurately the azimuth distribution, the
reby allowing the calculation of the disturbances' location in the pla
smasphere independently of the measured velocity. The measurable veloc
ity due to corotation is calculated and subtracted from the measured t
race velocity. This difference, or deviation from corotation, is attri
buted to electrodynamic convection; the measurement of plasmaspheric c
onvection may lead to the eventual monitoring of mid-latitude electric
fields. Disturbances are seen convecting predominantly westward, with
the fastest having angular velocities greater than the anticorotating
VLA line of sight. The direction of convection and conditions of obse
rvations indicate that the disturbances are likely the same phenomenon
seen by the Los Alamos satellite beacon array.