SM12B-03
Substorm Bulge/Surge Controlled by Polar Cap Flow Channels
Monday, 14 December 2015: 10:50
2009 (Moscone West)
Larry R Lyons1, Toshi Nishimura1, Ying Zou2, Bea Gallardo-Lacourt1, Eric Donovan3, Kazuo Shiokawa4, Michael J Nicolls5, Steven Chen5, J. Michael Ruohoniemi6, Nozomu Nishitani7 and Kathryn A McWilliams8, (1)University of California Los Angeles, Los Angeles, CA, United States, (2)UCLA, Los Angeles, CA, United States, (3)University of Calgary, Calgary, AB, Canada, (4)Nagoya University, Nagoya, Japan, (5)SRI International Menlo Park, Menlo Park, CA, United States, (6)Virginia Tech, Blacksburg, VA, United States, (7)Nagoya University, Solar-Terrestrial Environment Laboratory, Nagoya, Japan, (8)University of Saskatchewan, Saskatoon, SK, Canada
Abstract:
Previous studies have provided evidence that localized channels of enhanced polar cap flow drive plasma sheet/auroral oval flow channels, auroral poleward boundary intensifications and streamers, and substorm onset. Evidence has also indicated that a persistence of such flow channels after substorm onset may enhance post-onset auroral poleward expansion and activity. Here, we combine auroral imager and radar observations to show evidence that polar-cap flow channels can directly feed the substorm bulge westward motion, i.e., the westward traveling surge, and its poleward expansion well into the pre-existing polar cap. By taking advantage of the capability of tracing polar cap arcs and patches over long distances with red line imaging, we are able to trace flow features that strongly affect the substorm bulge across the polar cap for up to ~1-1.5 hr prior to their impacting and affecting the substorm bulge.
