Ionospheric delay effect is a critical issue that limits the accuracy of precise Global Navigation Satellite System (GNSS) positioning and navigation for single-frequency users, especially in mid- and low-latitude regions where variations in the ionosphere are larger. Kriging spatial interpolation techniques have been recently introduced to model the spatial correlation and variability of ionos...

[1] A new algorithm for retrieving the relative ionospheric satellite-to-satellite total electron content during Global Positioning System (GPS) radio occultations is proposed. The algorithm consists of a linear combination of the L1 and L2 excess phase data using precise orbit information of the transmitter and receiver. The combination eliminates the effects of refractive bending and dispersi...

-This study is a preliminary analysis of the accuracy of various ionosphere models to correct single frequency altimeter height measurements for ionospheric path delay. In particular, research focused on adjusting empir/cal and parameterized ionosphere models in the parameterized real-time ionospheric specification modal (PRISM) 1.2 using total electron content (TEC) data from the global positi...

[1] The Jet Propulsion Laboratory/University of Southern California Global Assimilation Ionospheric Model (JPL/USC GAIM) uses two data assimilation techniques to optimally combine ionospheric measurements with the physics model: a sparse, traditional Kalman filter to estimate the three-dimensional density state, and a four-dimensional variational approach (4DVAR) to estimate ionospheric drivers...

We compare TEC measurements from the NASA Radar Altimeter and DORIS instrument on board TOPEX/POSEIDON with GPS TEC estimates , and evaluate diierent GPS data analysis strategies. We verify that global tomographic GPS analysis using a voxel grid is well suited for ionospheric calibration of altimeters. We show that a 1-day t of 20-second-averaged NRA ionospheric correction data versus GPS tomog...

A major error component of Global Positioning System (GPS) is the ionospheric delay. Ionopspheric error can be reduced by a dual frequency receiver using a linear combination technique that can not be applied with a single frequecy receiver. However, an accurate ionospheric error modeling for single-frequency receiver is required. Due to the nonlinearity of the ionospheric error, a highly nonli...

The ionosphere affects the electromagnetic waves that pass through it by inducing an additional transmission time delay. The ionosphere influence has now become the largest error source in GPS positioning and navigation after the turn-off of the Selective Availability (SA). In this paper, methods of 2D gridbased and 3D tomography-based ionospheric modeling are developed based on regional GPS re...

I.inc-of-sight ionosphere measurements derived from differcncing dual-frequency Global Positioning System (GPS) range data are corrupted by instrumental biases in both the receiver and GPS satellite transmitters due to hardware delays in the L1 and L2 signal paths, The lineof-sight differential delay can be modeled as the sum of a rccciver bias, a satellite transmitter bias, and the line-ofsigh...