HR: 1340h
AN: SM23A-0468    [Abstracts]
TI: A Search for Signatures of Ion Acoustic Shoulders in the SERSIO sounding rocket data set
AU: * Ellis, A T
EM: armin.ellis@dartmouth.edu
AF: Dartmouth College, Thayer School, Hanover, NH 03755 United States
AU: Lessard, M R
EM: marc.lessard@dartmouth.edu
AF: University of New Hampshire, Morse Hall 39 College Road, Durham, NH 03824
AU: Kintner, P M
EM: pmk1@cornell.edu
AF: Cornell University, 302 Rohdes Hall School of Electrical and Computer Engineering, Ithaca, NY 14853 United States
AU: Lynch, K A
EM: kristina.lynch@dartmouth.edu
AF: Dartmouth College, Department of Physics and Astronomy, Hanover, NH 03755 United States
AU: Klatt, E
EM: klatt@ece.cornell.edu
AF: Cornell University, 302 Rohdes Hall School of Electrical and Computer Engineering, Ithaca, NY 14853 United States
AU: Oksavik, K
EM: kjellok@ulrik.uio.no
AF: University of Oslo, Department of Physics PB 1048 - Blindern, Oslo, N-0316 Norway
AB: Although first predicted in the early 1960's, enhanced Ion Acoustic Shoulders have only been observed by incoherent scatter radars since the late 1980's. The signature of an IAS is seen as a positive and negative frequency shift about the center radar frequency. These features occur at altitudes of 150 to over 600 km, peaking at 500 km, with spatial extent (perpendicular to the magnetic field) the order of 10 km. The occurrence distribution shows a maximum in the pre-midnight region, with a secondary peak on the dayside (Rietveld et al 1995). Observations of strong (1000 mA/${\rm m}^2$), localized currents by EISCAT have led to theories based on current-driven instabilities as the source of these waves (Forme, 1993; St.-Maurice et al., 1996). The SERSIO (Svalbard EISCAT Rocket Study of Ion Outflows) sounding rocket mission was launched into CME-driven dayside aurora on the 22nd of January 2004 at 0857 UT (0436 MLT) from Ny-Alesund ($78^\circ$ 55' 11" N, $11^\circ$ 56' 60" E) and reached an apogee of 782 km. During the flight, the EISCAT incoherent scatter radar network supported the mission by monitoring altitude profiles of electron and ion density, velocity and temperature. From Longyearbyen, located approximately 50 km south east of Ny-Alesund and near the trajectory of SERSIO, the 32m ESR dish was tracking the ionospheric footprint of the payload while the 42 m dish was making local field-aligned measurements. The data from these radars clearly indicated the presence of enhanced ion acoustic shoulders, suggesting that SERSIO flew through a 'field' of Ion Acoustic Shoulders. In fact, the plasma wave environment observed by SERSIO was composed of traditional VLF hiss and Broad Band ELF hiss with wavelengths less than the order of 6m. Here we present the result of our search for Ion Acoustic Shoulders in the SERSIO data set.
DE: 7894 Instruments and techniques
DE: 2407 Auroral ionosphere (2704)
DE: 2409 Current systems (2708)
DE: 2704 Auroral phenomena (2407)
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting