HR: 1340h
AN: SA33A-1140    [Abstracts]
TI: GPS Occulation Observations of Equatorial Scintillation: Dependence on Magnetic Field Orientation, Longitude, and Season
AU: * Anderson, P C
EM: phillip.anderson1@utdallas.edu
AF: University of Texas at Dallas, Box 830688 FO22, Richardson, TX 75083 United States
AU: Straus, P R
EM: paul.r.straus@aero.org
AF: The Aerospace Corporation, Box 92957 M2/259, Los Angeles, CA 90009 United States
AB: We analyzed GPS occultation data from the CHAMP, SAC-C, and PICOSat satellite for the entire year 2002 identifying radiowave scintillation occurrence from SNR measurements of the C/A code on the L1 frequency obtained at the 1-second rate cadence. Global distributions clearly indicate that we are observing equatorial scintillation and scintillation in the auroral zones and polar cap. Seasonal and magnetic local time distributions of the low-latitude observations are in good agreement with the known distributions of equatorial scintillation. Longitudinal distributions vary somewhat from the WBMOD climatological model, particularly in the African sector where scintillation is observed nearly all year. A strong dependence on the orientation of the occultation ray path with the magnetic field orientation is observed with a low probability of scintillation at ray path angles perpendicular to the magnetic field and high probability of observations at smaller angles. This is interpreted as the result of the orientation of the ionospheric bubbles responsible for the scintillation. The walls of the bubbles, on which the instabilities that cause the scintillation occur, are typically aligned with the magnetic field. Thus, occultation ray paths along the magnetic field pass along the edge of the bubbles and remain within the region of instabilities for a longer period that ray paths perpendicular to the magnetic field and the bubble walls.
DE: 2415 Equatorial ionosphere
DE: 2435 Ionospheric disturbances
DE: 2439 Ionospheric irregularities
DE: 2494 Instruments and techniques
SC: SPA-Aeronomy [SA]
MN: 2004 AGU Fall Meeting