First assimilations of COSMIC radio occultation data into the Electron Density Assimilative Model (EDAM)

Angling, Matthew

doi:10.5194/angeo-26-353-2008

Cited by 36 publications

(31 citation statements)

References 11 publications

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“…Thus, IRO data include day and night, summer, winter and equinoxes at high, medium and low latitudes. In general, the retrieved NmF2 and hmF2 by IRO techniques are in good agreement with ionosonde observations at medium latitudes (Jakowski et al, 2004;Angling, 2008). However, the accuracy of the reconstructed electron density profiles may degrade as a consequence of strong spatial gradients in the ionosphere, especially in the equatorial anomaly regions (Yue et al, 2010).…”

Section: Data Sourcessupporting

confidence: 66%

A new global model for the ionospheric F2 peak height for radio wave propagation

Hoque

Jakowski

2012

Ann. Geophys.

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Abstract. The F2-layer peak density height hmF2 is one of the most important ionospheric parameters characterizing HF propagation conditions. Therefore, the ability to model and predict the spatial and temporal variations of the peak electron density height is of great use for both ionospheric research and radio frequency planning and operation. For global hmF2 modelling we present a nonlinear model approach with 13 model coefficients and a few empirically fixed parameters. The model approach describes the temporal and spatial dependencies of hmF2 on global scale. For determining the 13 model coefficients, we apply this model approach to a large quantity of global hmF2 observational data obtained from GNSS radio occultation measurements onboard CHAMP, GRACE and COSMIC satellites and data from 69 worldwide ionosonde stations. We have found that the model fits to these input data with the same root mean squared (RMS) and standard deviations of 10 %. In comparison with the electron density NeQuick model, the proposed Neustrelitz global hmF2 model (Neustrelitz Peak Height Model -NPHM) shows percentage RMS deviations of about 13 % and 12 % from the observational data during high and low solar activity conditions, respectively, whereas the corresponding deviations for the NeQuick model are found 18 % and 16 %, respectively.

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Section: Data Sourcessupporting

confidence: 66%

A new global model for the ionospheric F2 peak height for radio wave propagation

Hoque

Jakowski

2012

Ann. Geophys.

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“…The majority of the input data is GPS TEC derived from the ground-based GNSS stations of the International GNSS Service (IGS). However, EDAM also deals with ionospheric radio occultation (IRO), ionosonde data and in situ electron density measurements; see Angling et al (2008). Bust et al (2004) developed a similar approach, the Ionospheric Data Assimilation ThreeDimensional (IDA3-D) technique based on 3-D variational data assimilation.…”

Section: Introductionmentioning

confidence: 99%

Tomography of the ionospheric electron density with geostatistical inversion

et al. 2015

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Abstract. In relation to satellite applications like global navigation satellite systems (GNSS) and remote sensing, the electron density distribution of the ionosphere has significant influence on trans-ionospheric radio signal propagation. In this paper, we develop a novel ionospheric tomography approach providing the estimation of the electron density's spatial covariance and based on a best linear unbiased estimator of the 3-D electron density. Therefore a non-stationary and anisotropic covariance model is set up and its parameters are determined within a maximum-likelihood approach incorporating GNSS total electron content measurements and the NeQuick model as background. As a first assessment this 3-D simple kriging approach is applied to a part of Europe. We illustrate the estimated covariance model revealing the different correlation lengths in latitude and longitude direction and its non-stationarity. Furthermore, we show promising improvements of the reconstructed electron densities compared to the background model through the validation of the ionosondes Rome, Italy (RO041), and Dourbes, Belgium (DB049), with electron density profiles for 1 day.

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“…To get comprehensive 3-D reconstructions in the future, the step of assimilation of data providing more information about the vertical distribution, like ionosonde profiles and ionospheric radio occultation profiles, may prove important and promising (see McNamara et al, 2007;Angling 2008). Moreover, in order to improve the data coverage and measurement geometry we will assimilate space-based GNSS sTEC and further ground-based sTEC measurements available due to the recent development and modernisation of the different GNSS (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…Also, other techniques, taking advantage of spatial and temporal covariance information, such as optimal interpolation, Kalman filter and kriging, have been applied (see e.g. Angling and Cannon, 2004;Angling and Khattatov, 2006;Angling et al, 2008;Gerzen et al, 2015;Pérez, 2005) to update the modelled electron density distributions. Moreover, there are approaches based on physical models that combine the estimation of electron density with physical related variables, such as neutral winds or oxygen/nitrogen ratio (see Schunk et al, 2004;Wang et al, 2004).…”

Section: T Gerzen and D Minkwitz: Smart For 3-d Ionosphere Tomographymentioning

confidence: 99%

Simultaneous multiplicative column-normalized method (SMART) for 3-D ionosphere tomography in comparison to other algebraic methods

Gerzen

Minkwitz

2016

Ann. Geophys.

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Abstract. The accuracy and availability of satellite-based applications like GNSS positioning and remote sensing crucially depends on the knowledge of the ionospheric electron density distribution. The tomography of the ionosphere is one of the major tools to provide link specific ionospheric corrections as well as to study and monitor physical processes in the ionosphere.In this paper, we introduce a simultaneous multiplicative column-normalized method (SMART) for electron density reconstruction. Further, SMART+ is developed by combining SMART with a successive correction method. In this way, a balancing between the measurements of intersected and not intersected voxels is realised. The methods are compared with the well-known algebraic reconstruction techniques ART and SART. All the four methods are applied to reconstruct the 3-D electron density distribution by ingestion of ground-based GNSS TEC data into the NeQuick model.The comparative case study is implemented over Europe during two periods of the year 2011 covering quiet to disturbed ionospheric conditions. In particular, the performance of the methods is compared in terms of the convergence behaviour and the capability to reproduce sTEC and electron density profiles. For this purpose, independent sTEC data of four IGS stations and electron density profiles of four ionosonde stations are taken as reference. The results indicate that SMART significantly reduces the number of iterations necessary to achieve a predefined accuracy level. Further, SMART+ decreases the median of the absolute sTEC error up to 15, 22, 46 and 67 % compared to SMART, SART, ART and NeQuick respectively.

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First assimilations of COSMIC radio occultation data into the Electron Density Assimilative Model (EDAM)

Cited by 36 publications

References 11 publications

A new global model for the ionospheric F2 peak height for radio wave propagation

A new global model for the ionospheric F2 peak height for radio wave propagation

Tomography of the ionospheric electron density with geostatistical inversion

Simultaneous multiplicative column-normalized method (SMART) for 3-D ionosphere tomography in comparison to other algebraic methods

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