HR: 17:06h
AN: SM44A-06    [Abstracts]
TI: Periodic Variations of Low Energy Ion Fluxes In Jupiter's Magnetotail
AU: * Elliott, H A
EM: helliott@swri.edu
AF: Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228-0510, United States
AU: McComas, D J
EM: dmccomas@swri.edu
AF: Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228-0510, United States
AU: Bagenal, F
EM: bagenal@lasp.colorado.edu
AF: University of Colorado, UCB 392 University of Colorado, Boulder, CO 80309-0392, United States
AU: Hill, M E
EM: Matthew.Hill@jhuapl.edu
AF: Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723-6099, United States
AU: Samara, M
EM: msamara@swri.edu
AF: Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228-0510, United States
AB: The New Horizons spacecraft traveled ~2000 Rj down Jupiter's magnetotail. The objective of this study is to quantify the periodicities present at several distances along the New Horizons trajectory through Jupiter's magnetotail. Initial examination of Solar Wind Around Pluto (SWAP) low energy ion measurements indicate distinct periodicities with periods close to 10 hours as well as longer periods of 3-4 days. Similar periodicities were observed with previous missions that explored within 200 Rj of the planet, and more recently by the Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) instrument, also on New Horizons in the 30keV – 1 MeV ion intensities. In this study we focus on shorter periods closer to 10 hours since those are more distinct and occur both close and far from the planet. Approximately 10 hour periodicities in the count rates were observed near 430 Rj and again near 1500Rj just prior to New Horizons entering the magnetosheath. In Jupiter's magnetosphere each set of SWAP measurements consist of two consecutive 32 second sweeps followed by a 256 sec gap. Since the SWAP measurements have uneven time spacing, using Lomb-Scargle periodograms is a more appropriate method for determining the spectrum than using a power spectrum derived from a Fast Fourier Transform (FFT). We will verify the Lomb-Scargle periodograms by determining the power spectrum with the FFT using only the first sweep of each set of observations since this provides the regular time spacing required for FFTs. We hope to gain insight into the physical implications by comparing intervals at different distances from Jupiter, and by comparing SWAP and PEPSSI measurements of the same time intervals.
DE: 5737 Magnetospheres (2756)
DE: 6220 Jupiter
DE: 7800 SPACE PLASMA PHYSICS
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting