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Spatial structure of ionospheric convection velocities in regions of open and closed magnetic field topology
Author(s) -
Abel G. A.,
Freeman M. P.,
Chisham G.
Publication year - 2006
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl027919
Subject(s) - geophysics , ionosphere , physics , field line , magnetosphere , magnetic field , convection , computational physics , geology , mechanics , quantum mechanics
We present a spatial structure function analysis of ionospheric velocity, measured by the Halley Super Dual Auroral Radar Network (SuperDARN) radar over five years. We show evidence for scale‐free velocity fluctuations for separations from 45 km to ∼1000 km. For larger separations a deviation from scale‐free structure is seen that we interpret as the influence of the global convection pattern. We find evidence for scale‐free structure in regions of both open and closed field line topology, though with different power‐law exponents. The measured power‐law exponents poleward and equatorward of the open‐closed field line boundary are 0.31 and 0.39 respectively. We propose that the scale‐free spatial structure of ionospheric velocity fluctuations on open magnetic field lines is a reflection of the spatial structure of the solar wind and the scale‐free spatial structure of ionospheric velocity fluctuations on closed magnetic field lines is dictated by the internal dynamics of the magnetosphere‐ionosphere system.