EISCAT verification in the development of ionospheric tomography

Walker, I. K.; Heaton, J. A. T.; Kersley, L.; Mitchell, Cathryn N.; Pryse, S. E.; Williams, Meredith

doi:10.1007/s00585-996-1413-8

Cited by 23 publications

(12 citation statements)

References 6 publications

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“…The European Incoherent Scatter radar facility (EISCAT) has played a crucial role in the development of ionospheric tomography, in providing independent veri®cation of tomographic images. An overview of this important role is given by Walker et al (1996). Comparisons of tomographic reconstructions of ionospheric plasma distribution and EISCAT observations have been used to investigate several aspects of the technique.…”

Section: Introductionmentioning

confidence: 99%

The spatial structure of the dayside ionospheric trough

et al. 1998

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Abstract. Tomographic imaging provides a powerful technique for obtaining images of the spatial distribution of ionospheric electron density at polar latitudes. The method, which involves monitoring radio transmissions from the Navy Navigation Satellite System at a meridional chain of ground receivers, has particular potential for complementing temporal measurements by other observing techniques such as the EISCAT incoherent-scatter radar facility. Tomographic reconstructions are presented here from a two-week campaign in November 1995 that show large-scale structuring of the polar ionosphere. Measurements by the EISCAT radar confirm the authenticity of the technique and provide additional information of the plasma electron and ion temperatures. The dayside trough, persistently observed at high latitudes during a geomagnetically quiet period but migrating to lower latitudes with increasing activity, is discussed in relationship to the pattern of the polar-cap convection.Key words. Ionosphere-magnetosphere interactions · Polar ionosphere · Radio science · Ionospheric propagation

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Section: Introductionmentioning

confidence: 99%

The spatial structure of the dayside ionospheric trough

et al. 1998

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“…The technique became popular after Austen et al (1988) demonstrated the feasibility to image ionospheric electron density distributions. Two-dimensional ionospheric profile sections varying in latitude and height were initially reconstructed using Navy Navigation Satellite System observations (Andreeva et al 1990;Fougere 1995;Walker et al 1996;Sutton and Na 1996;Kunitsyn et al 1997). In recent years, many researchers have been involved investigating GPS-based CIT (Ruffini et al 1999;Mitchell and Spencer 2003;Ma and Maruyama 2005;Stolle et al 2006;Jin et al 2006;Wen et al 2007a, b, c).…”

Section: Introductionmentioning

confidence: 98%

A new two-step algorithm for ionospheric tomography solution

2011

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Ionospheric tomography inverse algorithms are usually an ill-conditioned problem because the geometric distribution of continuously operating reference GPS stations is not ideal for this task. In order to cope with such ill-conditioning, a new tomographic algorithm, termed two-step algorithm (TSA), is presented. The electron density is estimated in two steps: Phillips smoothing method (PSM) is first used to resolve the ill-conditioned problem in the ionospheric tomography system, and then, the PSM solution is input as an initial value to the multiplicative algebraic reconstruction technique (MART) and iteratively improved. Numerical simulations using the International Reference Ionosphere 2007 model demonstrate that the TSA is applicable to GPS-based ionospheric tomography reconstruction and is superior to PSM and MART when these techniques are used alone. The new algorithm is applied to reconstruct the ionospheric electron density distribution over China using GPS observations, and a comparison with ionosonde observations is made.

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“…Radio tomography was introduced by Austen et al [1988] and has since been successfully used for the characterization of ionospheric structure [ Fougere , 1995; Walker et al , 1996; Sutton and Na , 1996; Kamalabadi et al , 1999] by integrated line‐of‐sight measurements. Radio tomography has recently been shown to be a promising new technique for large‐scale remote sensing of Earth's magnetosphere in theoretical studies with magnetohydrodynamic (MHD) simulations [ Ergun et al , 2000; Ganguly et al , 2000; Zhai and Cummer , 2005], as well as in satellite radio propagation experiments [ Cummer et al , 2001; Cummer et al , 2003].…”

Section: Introductionmentioning

confidence: 99%

An orthogonal projection and regularization technique for magnetospheric radio tomography

Zhai

Cummer

2006

J. Geophys. Res.

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[1] A challenging problem in ill-posed inverse problems is incorporating prior knowledge of the solution into reconstruction techniques. This problem is particularly important in magnetospheric radio tomography where the path integrated measurements of the target region may be sparse. We present in this paper an orthogonal projection and regularization (OPR) technique that incorporates prior knowledge of magnetospheric parameters from existing models or past measurements into a direct reconstruction algorithm. The OPR scheme extracts first an optimal orthonormal basis containing the main features of the unknowns from an ensemble of modeled or measured snapshots through the proper orthogonal decomposition (POD) and then projects the line-of-sight equations onto the subspace spanned by the empirical orthonormal basis. The resulting low-dimensional model is well-conditioned, its coordinates are uncorrelated, and it contains prior knowledge of the solution. The magnetospheric parameters in the transformed coordinate are reconstructed from the low-dimensional model and quantities in the physical coordinate are easily recovered from the POD transformation. On the basis of magnetohydrodynamic (MHD) simulations and hypothetical satellite constellations, we demonstrate that the POD-based method may perform significantly better than the regularized direct method with sparse path-integrated measurements, combined with a few (5-10) model snapshots.Citation: Zhai, Y., and S. A. Cummer (2006), An orthogonal projection and regularization technique for magnetospheric radio tomography,

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EISCAT verification in the development of ionospheric tomography

Cited by 23 publications

References 6 publications

The spatial structure of the dayside ionospheric trough

The spatial structure of the dayside ionospheric trough

A new two-step algorithm for ionospheric tomography solution

An orthogonal projection and regularization technique for magnetospheric radio tomography

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