HR: 1400h
AN: SM33C-02    [Abstracts]
TI: Magnetic Pulsation and Riometer Absorption Signatures During Two Geomagnetic Storms in Late 2006
AU: Posch, J
EM: posch@augsburg.edu
AF: Augsburg College, Minneapolis, MN, United States
AU: * Engebretson, M J
EM: engebret@augsburg.edu
AF: Augsburg College, Minneapolis, MN, United States
AU: Lessard, M R
EM: marc.lessard@UNH.edu
AF: University of New Hampshire, Durham, NH, United States
AU: Detrick, D L
EM: detrick@umd.edu
AF: University of Maryland, College Park, MD, United States
AU: Weatherwax, A T
EM: aweatherwax@siena.edu
AF: Siena College, Loudonville, NY, United States
AU: Manninen, J
EM: Jyrki.Manninen@sgo.fi
AF: Sodankylä Geophysical Observatory, Sodankyla, Finland
AU: Rose, M C
EM: MCR@bas.ac.uk
AF: British Antarctic Survey, Cambridge, United Kingdom
AB: Late in 2006 two geomagnetic storms occurred with minimum Dst of -96 nT and -187 nT on November 30 at 14 UT and December 15 at 8 UT, respectively. The occurrences and latitudinal patterns of broadband and narrowband magnetic pulsations in the Pc1-2 frequency band (0.1-5 Hz) at various latitudes in both hemispheres were compared to the signatures of riometer absorption at the same locations for these two storm intervals. We used data from Antarctic search coil magnetometers and riometers located at Halley (-62° MLAT), AGO P2 (-70° MLAT), South Pole (-74° MLAT), and McMurdo (-80° MLAT) and from Northern hemisphere sites Sondrestrom, Greenland (74° MLAT) and the seven-station Finnish chain (57° - 72° MLAT). During the main phase of the December 2006 storm and continuing into the local morning sector of the following day, Pi1-2 broadband noise was the dominant feature at all latitudes in both hemispheres and was accompanied by increased riometer absorption. Narrowband Pc1-2 waves began to occur 5 hours after minimum Dst at the lowest latitude Finnish station and 6 hours after at the higher latitude Finnish stations. The Antarctic stations, located ~5 hours MLT farther west, detected similar Pc1-2 activity 8 hours after minimum Dst. In contrast, during the November 2006 storm Pc1-2 activity occurred 3 hours after minimum Dst at Halley and not until the following day at the Finnish stations and other Antarctic stations. We believe this is a local time effect; during both storms the Pc1-2 activity occurred first at sites which were in the noon-afternoon sector. Both arrays showed continued Pc1-2 activity for 2-3 days after each storm, while broadband ULF noise and riometer absorption diminished.
DE: 2716 Energetic particles: precipitating
DE: 2752 MHD waves and instabilities (2149, 6050, 7836)
DE: 2774 Radiation belts
DE: 2788 Magnetic storms and substorms (7954)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Joint Assembly