HR: 11:55h
AN: SM22A-07    [Abstracts]
TI: Multipoint observations of quasi-periodic substorms associated with ULF pulsations
AU: * Lee, D
EM: dylee@chungbuk.ac.kr
AF: Chungbuk National University, 410 Sungbong-ro, Heungduk-gu, Cheongju, 361-763, Korea, Republic of
AU: Lyons, L
EM: larry@atmos.ucla.edu
AF: UCLA, Dept of Atmospheric Sciences, Los Angeles, CA 90095-1565, United States
AU: Zou, S
EM: sha@atmos.ucla.edu
AF: UCLA, Dept of Atmospheric Sciences, Los Angeles, CA 90095-1565, United States
AU: Kim, K
EM: kckim@chungbuk.ac.kr
AF: Chungbuk National University, 410 Sungbong-ro, Heungduk-gu, Cheongju, 361-763, Korea, Republic of
AU: Ruohoniemi, J M
EM: Mike.Ruohoniemi@jhuapl.edu
AF: JHU, Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723-6099, United States
AU: Weygand, J M
EM: jweygand@igpp.ucla.edu
AF: UCLA, IGPP, Los Angeles, CA 90095-1565, United States
AB: Using auroral images from the IMAGE WIC instrument, geomagnetic data from various ground stations, and geosynchronous particle data, we have identified six consecutive substorms separated by about 45 min to 1.6 hr on November 8, 2000. Most of these substorms are of small to medium size and occurred under a weakly northward IMF condition: IMF Bz was near zero to about +5 nT prior to each substorm. IMF By was also weak, being within about ¢®¨ú3 nT. Most interestingly, we have found that for most of the substorms, about 10-15 min period ULF pulsation begins to amplify prior to each onset and tends to decline near the time of onset. The pulsation features are clearly seen at auroral zone and some higher latitude stations of the CANOPUS magnetic network when they cover morning side MLT regions. Similar features are also seen in the GOES magnetic field observations in similar MLT regions. For the first two substorms, the IMAGE magnetic network stations were at postnoon MLT regions and indicated similar ULF pulsation features. The SuperDARN data show that for most of the substorms, the ionospheric convection within the polar cap shows high-amplitude oscillations with a period of about 15 min that tend to amplify prior to onset and to decline after the onset. Based on the results, we will discuss the possible association between substorm triggering and convection associated with large-amplitude ULF pulsations.
DE: 2730 Magnetosphere: inner
DE: 2760 Plasma convection (2463)
DE: 2784 Solar wind/magnetosphere interactions
DE: 2788 Magnetic storms and substorms (7954)
DE: 2790 Substorms
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting