Ionospheric convection at Casey, a southern polar cap station
Author(s) -
Smith P. R.,
Dyson P. L.,
Monselesan D. P.,
Morris R. J.
Publication year - 1998
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/97ja02819
Subject(s) - ionosphere , convection , noon , physics , geophysics , interplanetary magnetic field , earth's magnetic field , polar , latitude , dusk , f region , geology , atmospheric sciences , geodesy , solar wind , meteorology , plasma , magnetic field , astronomy , quantum mechanics
A digital ionosonde (Digisonde Portable Sounder 4) located at Casey, Antarctica (66.3°S, 110.5°E, −80.8° corrected geomagnetic latitude) has been operational since early 1993 and has accumulated 3 years of plasma drift measurements, providing an excellent data set for studying the characteristics of ionospheric convection flow at a southern polar cap station. The purpose of this study is to investigate the influence of the IMF on the F region ionospheric convection over Casey and to compare it to the Heppner‐Maynard satellite‐derived electric field models. We find clear dependencies in the drift on the sign and strength of the IMF B y and B z components and with Kp . Antisunward flow dominates during B z south conditions, turning to have a sunward component around noon when B z is northward. The B y component causes the entire convection system to rotate and distorts the dayside flow in the proximity of the throat, with a dawnward (duskward) component for B y negative (positive). Comparison with the B z south Heppner‐Maynard BC, DE, and A patterns is favorable at most times, although we predict a rounder, more dominant dusk (dawn) cell and a smaller crescent‐shaped dawn (dusk) cell for B y < 0 ( B y > 0). There is a dependence on Kp when B z is south in both the model and the drifts, flow directions becoming more antisunward and velocities becoming higher on the dayside as Kp increases. This implies the polar cap is expanding under conditions of enhanced reconnection. When B z is north, the F region drift agreement with the BCP(P) and DEP(P) models is excellent on the dawn (dusk) side for B y < 0 ( B y > 0) but diverges on the opposite side as the pattern flow lines twist sunward. Separation of the drifts into B z weakly (<3 nT) and strongly (>3 nT) northward cases did not reveal any appreciable difference in the observed drift velocities.