Subdaily northern hemisphere ionospheric maps using an extensive network of GPS receivers

Wilson, Brian; Mannucci, Anthony J.; Edwards, C. D.

doi:10.1029/94rs03186

Cited by 124 publications

(66 citation statements)

References 4 publications

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“…Equation (1) is well suited for a regional or a global TEC model. It has been adopted to estimate the daily and sub-daily TEC model based on the global GPS surveying data set of IGS, and on the regional GPS surveying data sets obtained in North America and in Europe (Schaer et al, 1995;Wilson et al, 1995), respectively. An example of the GIM at UT01:05:00 on December 16, 2001 between the geomagnetic latitude range from 0 • to 45 • is given in the top image of plate 1.…”

Section: E13mentioning

confidence: 99%

“…Either global or regional GPS network has contribute to this research with different time and spatial resolution. (Wilson et al, 1995;Musman et al, 1997;Saito et al, 1998;Leonovich et al, 2000). Recently, following the increase of the density of the worldwide GPS network, and of the regional GPS networks like GEONET of Japan which has the average interstation distance as short as 25 kilometers (Miyazaki et al, 1997), the ionospheric irregularities have been studied with very high time resolution and spatial resolution as well as the high precision (Afraimovich et al, 2000;Ostuka et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

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Regional ionosphere map over Japanese Islands

et al. 2014

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Based on the high time and spatial resolution total electron content (TEC) data, which is estimated from the phase and code observables obtained by using GPS (Global Positioning System) Earth Observation Network (GEONET), the TEC distribution and its time variation over Japanese Islands are scaled into 0.5 • × 0.5 • grid data for each 10 minutes. The TEC daily map time series are arranged in an array to show the TEC evolution. Based on the spherical harmonics expansion of global ionospheric TEC model (GIM), which is estimated from global GPS observation, the TEC maps are expanded firstly through as high as 60 degrees and orders for a spherical harmonic function as a regional ionosphere map (RIM). The evolution history of medium scale traveling ionospheric disturbances (MSTIDs), i.e. polarward intense TEC enhancement and pre-noon rapid irregular fluctuations near the geomagnetic equator, are identified and confirmed in a quiet geomagnetic period.

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Section: E13mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Regional ionosphere map over Japanese Islands

et al. 2014

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“…Coco et al [1991] used this method to investigate the general tendency of the variability of the GPS instrumental biases. To improve the accuracy of the bias estimation, Wilson et al [1992Wilson et al [ , 1995 extended single-site technique proposed by Lanyi and Roth [1988] to a multisite one by modeling a global vertical TEC by two-dimensional spherical harmonics. They applied this technique to obtain the diurnal and semidiurnal average of the ionospheric TEC map of the Northern Hemisphere by using data from a global network of GPS stations.…”

Section: Introductionmentioning

confidence: 99%

Determination of GPS receiver differential biases by neural network parameter estimation method

Maruyama

et al. 2005

Radio Science

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[1] The dual-frequency signals of GPS can be used to measure the total electron content (TEC). The differential instrumental biases inherent in GPS satellite and receivers are considered as the main sources of error, and they must be removed for an accurate estimation of TEC. We aim at developing an effective method to solve the difficulties involved in the TEC measurement; there are only a few usable ground receivers, especially in lower-latitude areas near the geomagnetic equator where large ionospheric variability exists. For this purpose a new parameter estimation method based on a residual minimization training neural network is applied to determination of the GPS receiver biases. The alternative method is realized by making use of the excellent features of neural networks to approximate a wide range of mapping functions, for which the network training is carried out by minimizing squared residuals of integral equation. To determine receiver biases (unknown parameters), we used additional ''neural networks,'' each of which consists of only one neuron without an input channel. It is assumed that satellite biases have already been determined by applying the least squares method to the GEONET data gathered by a large number of receivers. Various cases of observation data for different seasons, different local times, and different geographic locations of the receiver as well as the cases of model data are analyzed, and it is confirmed that the method is very effective for a small number of receivers located in the lower-latitude areas.

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“…Recently, space-based radio navigation systems such as the US Global Positioning System (GPS) offer new opportunities for studying the ionosphere on a global scale (e.g. Coco, 1991;Wilson et al, 1995;Zarraoa and Sardon 1996). This is possible because GPS satellites transmit coherent dual-frequency signals in the L-band, low enough to measure a significant ionospheric contribution.…”

Section: Introductionmentioning

confidence: 99%

Relationships between GPS-signal propagation errors and EISCAT observations

Jakowski¹,

Sardón²,

Engler³

et al. 1996

Ann. Geophys.

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Abstract. When travelling through the ionosphere the signals of space-based radio navigation systems such as the Global Positioning System (GPS) are subject to modifications in amplitude, phase and polarization. In particular, phase changes due to refraction lead to propagation errors of up to 50 m for single-frequency GPS users. If both the L1 and the L2 frequencies transmitted by the GPS satellites are measured, first-order range error contributions of the ionosphere can be determined and removed by difference methods. The ionospheric contribution is proportional to the total electron content (TEC) along the ray path between satellite and receiver. Using about ten European GPS receiving stations of the International GPS Service for Geodynamics (IGS), the TEC over Europe is estimated within the geographic ranges!20°4 440°E and 32.5°4 470°N in longitude and latitude, respectively. The derived TEC maps over Europe contribute to the study of horizontal coupling and transport processes during significant ionospheric events. Due to their comprehensive information about the high-latitude ionosphere, EISCAT observations may help to study the influence of ionospheric phenomena upon propagation errors in GPS navigation systems. Since there are still some accuracy limiting problems to be solved in TEC determination using GPS, data comparison of TEC with vertical electron density profiles derived from EISCAT observations is valuable to enhance the accuracy of propagation-error estimations. This is evident both for absolute TEC calibration as well as for the conversion of ray-path-related observations to vertical TEC. The combination of EISCAT data and GPS-derived TEC data enables a better understanding of large-scale ionospheric processes.

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Subdaily northern hemisphere ionospheric maps using an extensive network of GPS receivers

Cited by 124 publications

References 4 publications

Regional ionosphere map over Japanese Islands

Regional ionosphere map over Japanese Islands

Determination of GPS receiver differential biases by neural network parameter estimation method

Relationships between GPS-signal propagation errors and EISCAT observations

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