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Plasma Sheet Convection Velocities Inferred From Electron Flux Measurements at Synchronous Altitude
Author(s) -
Shelley E. G.,
Johnson R. G.,
Sharp R. D.
Publication year - 1971
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/rs006i002p00305
Subject(s) - substorm , plasma sheet , convection , physics , energy flux , flux (metallurgy) , plasma , electric field , altitude (triangle) , geophysics , atmospheric sciences , magnetic field , electron , ionosphere , computational physics , magnetosphere , meteorology , materials science , geometry , astronomy , mathematics , quantum mechanics , metallurgy
Large increases in the low energy electron fluxes (0.5 to 50 kev) are observed to occur at synchronous altitude on most nights in the local evening or midnight sectors. These increases are usually found to be associated with magnetic substorms. The time of increase in the fluxes is found to be energy dependent, with the lower energy electrons nearly always being observed first for the evening and midnight events. If one interprets these flux increases as resulting from an inward convection of the plasma sheet in connection with a substorm, one can estimate the convection velocity at synchronous altitude from the measured energy dependent time of flux increase and earlier measurements [ Vasyliunas , 1968; Schield and Frank , 1970; Frank , 1970] of the energy dependent radial structure of the inner edge of the plasma sheet. The median velocity estimated from 38 cases by this technique is approximately 3 km/sec. This implies a westward electric field of approximately 0.36 mv/m, a value consistent with other measurements of this field.