Ionospheric convection response to changes of interplanetary magnetic field B(z) component during strong B(y) component

• Published in: Journal of Geophysical Research Vol. 105; no. A3; pp. 5231 - 5243
• Main Authors: Huang, Chao-Song, Murr, David, Sofko, George J, Hughes, W J, Moretto, Therese
• Format: Journal Article
• Language: English
• Published: 01-03-2000
• ISSN: 0148-0227

We investigate the ionospheric convection response to IMF B(z) changes during strong IMF B(y). On March 23, 1995, B(x) was small, B(y) was strongly positive (7-11 nT), and the B(z) polarity changed several times after 1300 UT. The dayside ionospheric convection is dominated by a large clockwise convection cell. The cell focus (the 'eye' of the convection pattern) is located in the prenoon sector for northward B(z) and in the postnoon sector for southward B(z). It is found that the cell focus shifts from the prenoon sector to the postnoon sector following a southward B(z) turning and vice versa for a northward B(z) turning. However, the motion of the convection cell, or the largest change in the convection pattern, is limited roughly to the region between the previous cell focus and the new cell focus. Outside this region, the ionospheric flows could be greatly enhanced or weakened, while the convection pattern shape changes very little. When B(y) is strong enough, the B(z) reorientation causes changes in the flow intensity but not in the shape of the convection pattern. The results show the characteristics of ionospheric convection response during strong B(y) and suggest that the convection reconfiguration is not only determined by the changing B(y) but also significantly influenced by the stable and large B(y). (Author)