SuperDARN studies of the ionospheric convection response to a northward turning of the interplanetary magnetic field |
| |
| Authors: | J R Taylor S W H Cowley T K Yeoman M Lester T B Jones R A Greenwald G Sofko J-P Villain R P Lepping M R Hairston |
| |
| Institution: | (1) Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, UK;(2) Applied Physics Laboratory, The Johns Hopkins University, Johns Hopkins Road, Laurel, Maryland 20723-6099, USA;(3) Institute for Space and Atmospheric Studies, University of Saskatchewan, P.O. Box 5190, Saskatoon, Saskatchewan, S7N 0W0, Canada;(4) CNRS/LPCE, 3A Avenue de la Recherche Scientifique, 45701 Orléans Cedex 2, France;(5) NASA Goddard Space Fight Center, Greenbelt, Maryland, 20771, USA;(6) W.B. Hansen Center for Space Sciences, University of Texas at Dallas, PO Box 830688, Richardson, Texas 75083, USA |
| |
| Abstract: | The response of the dayside ionospheric flow to a sharp change in the direction of the interplanetary magnetic field (IMF) measured by the WIND spacecraft from negative Bz and positive By, to positive Bz and small By, has been studied using SuperDARN radar, DMSP satellite, and ground magnetometer data. In response to the IMF change, the flow underwent a transition from a distorted twin-cell flow involving antisunward flow over the polar cap, to a multi-cell flow involving a region of sunward flow at high latitudes near noon. The radar data have been studied at the highest time resolution available ( 2 min) to determine how this transition took place. It is found that the dayside flow responded promptly to the change in the IMF, with changes in radar and magnetic data starting within a few minutes of the estimated time at which the effects could first have reached the dayside ionosphere. The data also indicate that sunward flows appeared promptly at the start of the flow change (within 2 min), localised initially in a small region near noon at the equatorward edge of the radar backscatter band. Subsequently the region occupied by these flows expanded rapidly east-west and poleward, over intervals of 7 and 14 min respectively, to cover a region at least 2 h wide in local time and 5° in latitude, before rapid evolution ceased in the noon sector. In the lower latitude dusk sector the evolution extended for a further 6 min before quasi-steady conditions again prevailed within the field-of-view. Overall, these observations are shown to be in close conformity with expectations based on prior theoretical discussion, except for the very prompt appearance of sunward flows after the onset of the flow change. |
| |
| Keywords: | Ionosphere (Auroral ionosphere) Magnetospheric physics (Magnetopause cusp and boundary layers Magnetosphere-ionosphere interaction) |
| 本文献已被 SpringerLink 等数据库收录！ |
|
