3-Dimensional Assimilative Ionospheric Modeling for Regions of Large TEC Gradient

Xiaoqing Pi, George A. Hajj, Brian D. Wilson, Anthony J. Mannucci, Attila Komjathy, Lukas Mandrake, Chunming Wang, and Gary Rosen

Abstract:	This paper introduces a 3-dimentional global assimilative ionospheric model (GAIM) developed by the University of Southern California and Jet Propulsion Laboratory Consortium. GAIM is built with a first-principle ionospheric model and a suite of optimization techniques including Kalman filter and a 4-dimentional variational approach (4DVAR) with an adjoint method and parameterization of model drivers. The first-principle model solves hydrodynamic equations numerically on a geomagnetic grid for ion and electron densities by dealing with physical processes including ionization, dynamics, and chemistry. The optimization techniques allow assimilation of various types of ionospheric measurements and bring the modeling in line with the measurements, as well as estimate the driving forces of ionospheric processes. In this paper, we present results of an experiment for modeling line-of-sight total electron content (TEC) at low latitudes in Brazil using GAIM assimilating dual-frequency GPS data collected from the South America region. The results are compared with a 2- D TEC mapping technique particularly at low elevation angles in regions of large TEC gradient. An improvement of 63% is achieved by the assimilative modeling for slant TEC at elevation angles lower than 30° through this preliminary analysis when compared with a planar fit algorithm.
Published in:	Proceedings of the 2004 National Technical Meeting of The Institute of Navigation January 26 - 28, 2004 The Catamaran Resort Hotel San Diego, CA
Pages:	753 - 760
Cite this article:	Pi, Xiaoqing, Hajj, George A., Wilson, Brian D., Mannucci, Anthony J., Komjathy, Attila, Mandrake, Lukas, Wang, Chunming, Rosen, Gary, "3-Dimensional Assimilative Ionospheric Modeling for Regions of Large TEC Gradient," Proceedings of the 2004 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2004, pp. 753-760.
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