Sunward flow region of the dayside reverse convection for northward interplanetary magnetic field

概要

論文の詳細を見る
Northward interplanetary magnetic field (IMF) causes a "reverse" plasma convection, i.e., having a sunward flow at the highest latitudes and anti-sunward flow on both sides of the sunward flow region, in the dayside polar ionosphere. Previous studies have shown that this sunward flow region is shifted in the dawn-dusk direction depending on IMF B_Y. This paper reports another new mode of the IMF controlled configuration of the sunward flow region, i.e., the expansion/reduction in the dawn-dusk direction. Seventy-two cases identified in the Dynamics Explores 2 dawn-dusk passes were analyzed. Results of statistical analyses show that the sunward flow region expands in the dawn-dusk direction when the magnitude of IMF in the Y-Z plane becomes large. This suggests that the dawn-dusk dimension of the reconnection region on the magnetopause poleward of the cusp extends in the dawn-dusk direction with increasing IMF magnitude in the Y-Z plane. When IMF tilts toward the tail lobe and the angle between the IMF vector projected to the X-Z plane and the Earth dipole axis is greater than 60°, this angle controls the dawn-dusk expansion/reduction of the sunward flow region dominantly.
国立極地研究所の論文