HR: 0830h
AN: SA21B-0089    [PDF]
TI: Comparison of IRI-2001 With TOPEX TEC Measurements
AU: * Jee, G
EM: sspkj@gaim.cass.usu.edu
AF: Utah State University, Center for Atmospheric and Space Sciences, 4405 Old Main Hill, Logan, UT 84322-4405 United States
AU: Schunk, R W
EM: schunk@cc.usu.edu
AF: Utah State University, Center for Atmospheric and Space Sciences, 4405 Old Main Hill, Logan, UT 84322-4405 United States
AU: Scherliess, L
EM: ludger@gaim.cass.usu.edu
AF: Utah State University, Center for Atmospheric and Space Sciences, 4405 Old Main Hill, Logan, UT 84322-4405 United States
AB: The International Reference Ionosphere (IRI) is an international joint project of the Committee on Space Research (COSPAR) and the International Union of Radio Science (URSI). As one of the most comprehensive empirical models of the ionosphere, the IRI provides the electron density, electron temperature, ion temperature, and ion composition in the altitude range from about 50 km to 2000 km, and also the TEC for a given location, time and date, based on the various measurements from the ground and space. During the last decade, the TOPEX/POSEIDON satellite mission has provided a wealth of data pertaining to TEC measurements over the oceans, and these data can be used to further improve the IRI. With this in mind, we compared a 10-year TOPEX TEC dataset with IRI predictions. The study covered solar cycle, seasonal, geomagnetic activity, and longitudinal variations. The resulting comparisons provide information on how to improve the IRI over the ocean areas. For low solar activity, IRI slightly overestimates TEC at low latitudes and underestimates it at middle and high latitudes at all local times. For the high solar activity, however, a large underestimate appears at low latitudes and extends to mid-latitudes, but with a smaller magnitude. At high latitudes, the IRI TEC shows an overestimate in both hemispheres for equinox and in the winter hemisphere for solstice, but it underestimates in the summer hemisphere. For the geomagnetic activity, we observed little effects on both TEC maps. Another important result is that right after sunrise, the IRI TEC at low latitudes starts to increase always earlier than the TOPEX TEC. At low latitudes, the TOPEX TEC shows stronger annual and semiannual variations than the IRI TEC, and at higher mid-latitudes, both TECs show the seasonal anomaly for high solar activity. Finally, both IRI and TOPEX TEC maps show significant longitudinal variations.
DE: 2415 Equatorial ionosphere
DE: 2443 Midlatitude ionosphere
DE: 2447 Modeling and forecasting
DE: 2467 Plasma temperature and density
SC: SPA - Aeronomy [SA]
MN: 2003 Fall Meeting