Ionospheric imaging at mid-latitudes using both GPS and ionosondes

Dear, Richard M.; Mitchell, Cathryn N.

doi:10.1016/j.jastp.2006.06.001

Cited by 4 publications

(5 citation statements)

References 21 publications

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“…Discrepancies with the GPS-reconstructed values can in part be explained by the fact that tomographic imaging using ground-based GPS data has a limited viewing angle of the line-integrated satellite-receiver path (Cilliers et al, 2004;Dear and Mitchell, 2007). Thus it is possible that the IRI-2001 density pro les used here to constrain the inversions are not distributing the electron density correctly over the imaging area investigated (as depicted in Fig.…”

Section: Resultsmentioning

confidence: 97%

“…The use of the MIDAS algorithm can be found in recent works for different latitudes and longitudinal sectors (see for example, Cilliers et al, 2004;Dear and Mitchell, 2007). The GPS navigation and observation data from RBMC/IBGE receivers were acquired at sampling intervals of 15 sec and used as input to the MIDAS tomographic algorithm.…”

Section: Methodsmentioning

confidence: 99%

“…For the former a solution is to implement a method to improve the basis set of vertical pro les by including into MIDAS algorithm, for example, real ionosonde, radio-occultation or Communication/Navigation Outage Forecasting System (C/NOFS) data. This solution with ionosonde data included has been demonstrated by Dear and Mitchell (2007), at least for mid-latitudes, to produce better peak electron density values without affecting the accuracy in vertical TEC representation. For the latter the solution is to increase the number and density of GPS receivers within the area of reconstruction, which will be throughout the next solar maximum years more than twice the present con guration.…”

Section: Remarks and Conclusionmentioning

confidence: 95%

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Tomographic imaging of the equatorial and low-latitude ionosphere over central-eastern Brazil

et al. 2011

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A four-dimensional time-dependent tomographic algorithm, named Multi Instrument Data Analysis System (MIDAS), is used to image the equatorial and low-latitude ionosphere over the central-eastern sides of the Brazilian territory. From differential phase data obtained by a chain of ground-based GPS receiver the total electron content (TEC) is estimated and then, together with a modeled ionosphere from International Reference Ionosphere (IRI) model, the electron density distribution is reconstructed and the parameters of the F 2 -peak layer are accessed from the images. This paper presents the rst study of ionospheric tomography using real dual-frequency data from the Brazilian Network for Continuous GPS Monitoring (RBMC). Ionospheric F 2 -peak electron density (N m F 2 ) accessed from the images are compared to concurrent measurements from three ionosondes installed across Brazil. One year of data during the solar maximum period from March/2001 to February/2002 is used to analyze the seasonal and hourly variation of the F 2 -layer peak density. The accuracy with which MIDAS images the electron density during geomagnetic quiet periods is investigated through its correlation and deviation with the ionosonde and IRI model data, respectively. The main aspects of the reconstruction results at the equatorial ionization anomaly (EIA) region over Brazil are highlighted and discussed.

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Section: Resultsmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

Section: Remarks and Conclusionmentioning

confidence: 95%

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Tomographic imaging of the equatorial and low-latitude ionosphere over central-eastern Brazil

et al. 2011

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“…Results are validated with data from the Jicamarca incoherent scatter radar and with independent GPS data. Previous work has investigated the use of ionosonde data in electron density tomography at midlatitudes [ García‐Fernández et al , 2003; Dear and Mitchell , 2007] and high latitudes [ Kersley et al , 1993] but this is the first study at low latitudes. This is important because the vertical electron density profile is harder to image at low latitudes due to the GPS satellite geometry.…”

Section: Introductionmentioning

confidence: 99%

The use of ionosondes in GPS ionospheric tomography at low latitudes

et al. 2012

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[1] A new technique is presented for the incorporation of ionosonde observations into GPS ionospheric tomography. This approach greatly improves the vertical resolution of the images when using independent incoherent scatter radar observations as ground truth, addressing a traditional weakness of tomographic techniques. Ionosonde observations are used to set vertical basis functions adaptively within the inversion as well as providing electron density information for direct assimilation. The technique also improves slant total electron content (TEC) accuracy in the vicinity of the ionosonde. An experiment was performed in the equatorial region of South America as a 6-day case study due to the availability of incoherent scatter and ionosonde data during this period. Preliminary results were validated with the Jicamarca incoherent scatter radar and independent GPS slant TEC observations. Using the incoherent scatter radar as ground truth for the vertical profile, the new technique reduces mean NmF2 error to À0.07 Â 10 11 electrons/m 3 compared with 0.27 Â 10 11 electrons/m 3 in a control run with no ionosonde data, while root-mean square error is now 0.5 Â 10 11 electrons/m 3 compared with 1.0 Â 10 11 electrons/m 3 in the control. The new technique also results in 0.1 km mean error in hmF2, compared with À3.9 km in the control, while root-mean square hmF2 error is around 40 km in both cases. Using independent slant TEC observations, the mean error is À0.36 TECU compared with 0.64 TECU in the control run, while root-mean square error is 3.55 TECU down from 4.02 TECU, suggesting the new technique also improves TEC values.

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“…The arrival of global, continuous data sets from diverse sources such as over 1200 GPS receivers across the globe, satellite – satellite crosslink occultations, digisonde profiles, in situ satellite density measurements, and ultraviolet (UV) airglow measurements from low‐Earth orbiters are fueling the need to create ionospheric models that are largely data driven, such as the persistence‐based multishell model, Global Ionospheric Mapping (GIM) [ Mannucci et al , 1998; Saito et al , 1998; Komjathy et al , 2005; Hernandez‐Pajares et al , 2009; Lee et al , 2008]. Three‐dimensional tomographic models have been developed such as MIDAS [ Dear and Mitchell , 2006], EDAM [ Angling and Cannon , 2004], and others [e.g., Rius et al , 1997]. Approaches such as IDA3D [ Bust and Crowley , 2007; Bust and Mitchell , 2008], attempt to incorporate data and ionospheric physics by use of empirical models (e.g., IRI) to help define the a priori state of the ionosphere prior to data input.…”

Section: Introductionmentioning

confidence: 99%

JPL/USC GAIM: On the impact of using COSMIC and ground‐based GPS measurements to estimate ionospheric parameters

Komjáthy

Wilson

et al. 2010

J. Geophys. Res.

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The University of Southern California (USC) and the Jet Propulsion Laboratory (JPL) have jointly developed the Global Assimilative Ionospheric Model (GAIM) to monitor space weather, study storm effects, and provide ionospheric calibration for space weather applications. JPL/USC GAIM is a physics‐based 3‐D data assimilation model that uses both four‐dimensional variational analysis and Kalman‐filter techniques to solve for the ion and electron density state and key drivers such as equatorial electrodynamics, neutral winds, and production terms. Here we report on GAIM Kalman filter‐based assimilation results using ground‐based GPS and COSMIC‐derived total electron count (TEC) measurements. We find that assimilating COSMIC measurements into GAIM improves critical ionospheric parameters such as NmF2 and HmF2. Assimilating COSMIC data produces higher‐accuracy vertical electron density profile “shapes,” as verified by comparisons to independent electron density profiles measured at Arecibo, Jicamarca, and Millstone Hill incoherent scatter radar (ISR). We also find significant improvement in global vertical TEC (VTEC) maps when assimilating COSMIC measurements, verified by comparing GAIM output with VTEC measurements from the Jason ocean altimeter. For 3 days in June 2006, improvement in accuracy compared to ground‐data‐only assimilation is found to be 30%, 28%, and 44%, respectively.

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Ionospheric imaging at mid-latitudes using both GPS and ionosondes

Cited by 4 publications

References 21 publications

Tomographic imaging of the equatorial and low-latitude ionosphere over central-eastern Brazil

Tomographic imaging of the equatorial and low-latitude ionosphere over central-eastern Brazil

The use of ionosondes in GPS ionospheric tomography at low latitudes

JPL/USC GAIM: On the impact of using COSMIC and ground‐based GPS measurements to estimate ionospheric parameters

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