Combination of different space-geodetic observations for regional ionosphere modeling

Dettmering, D; Schmidt, Michaël; Heinkelmann, Robert; Seitz, M.

doi:10.1007/s00190-010-0423-1

Cited by 66 publications

(44 citation statements)

References 16 publications

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“…It should be kept in mind that the F2 scale height differs with respect to bottomside and topside ionosphere but is assumed to be equal in the model approach presented here. Each of the key parameters can be modeled in terms of three 1-D endpoint-interpolating polynomial B spline functions with regard to longitude λ, latitude ϕ and time t with initially unknown series coefficients d. The basic theory about B spline modeling is, for example, given by Schumaker (1981) and Lyche and Schumaker (2000), and discussions on the application of B splines to model the regional vertical total electron content (VTEC) have already been published by Schmidt (2007), Zeilhofer et al (2008) and Dettmering et al (2011a). Polynomial B splines are chosen due to their advantage of the endpoint-interpolating and localizing characteristic for regional modeling, meaning that the spline values are constrained at the boundaries and generally are nonzero just within a compact interval.…”

Section: Modelmentioning

confidence: 99%

“…IRI-2007 is considered here as the only data source used for the derivation of initial and prior information since it complies with the criterion to provide data of all three key parameters where NmF2 and hmF2 as well as VTEC are directly available. The derivation of initial values and prior information for HF2 follows from the computation of the slab thickness τ , which is defined as the ratio between VTEC and NmF2, as introduced by Davies (1990). Moreover, Wright (1960) showed the equality of τ with 4.13 · H F2 for an α-Chapman layer.…”

Section: Initial and Prior Informationmentioning

confidence: 99%

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Regional representation of F2 Chapman parameters based on electron density profiles

Limberger¹,

Wu²,

Schmidt³

et al. 2013

Ann. Geophys.

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Abstract. Understanding the physical processes within the ionosphere is a key requirement to improve and extend ionospheric modeling approaches. The determination of meaningful parameters to describe the vertical electron density distribution and how they are influenced by the solar activity is an important topic in ionospheric research. In this regard, the F2 layer of the ionosphere plays a key role as it contains the highest concentration of electrons and ions. In this contribution, the maximum electron density NmF2, peak height hmF2 and scale height HF2 of the F2 layer are determined by employing a model approach for regional applications realized by the combination of endpoint-interpolating polynomial B splines with an adapted physics-motivated Chapman layer. For this purpose, electron density profiles derived from ionospheric GPS radio occultation measurements of the satellite missions FORMOSAT-3/COSMIC, GRACE and CHAMP have been successfully exploited. Profiles contain electron density observations at discrete spots, in contrast to the commonly used integrated total electron content from GNSS, and therefore are highly sensitive to obtaining the required information of the vertical electron density structure. The spatio-temporal availability of profiles is indeed rather sparse, but the model approach meets all requirements to combine observation techniques implicating the mutual support of the measurements concerning accuracy, sensitivity and data resolution. For the model initialization and to bridge observation gaps, the International Reference Ionosphere 2007 is applied. Validations by means of simulations and selected real data scenarios show that this model approach has significant potential and the ability to yield reliable results.

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Section: Modelmentioning

confidence: 99%

Section: Initial and Prior Informationmentioning

confidence: 99%

Regional representation of F2 Chapman parameters based on electron density profiles

Limberger¹,

Wu²,

Schmidt³

et al. 2013

Ann. Geophys.

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“…slant total electron content, sTEC) (Dettmering et al 2011;Herná ndez-Pajares et al 1999;Komjathy et al …”

Section: Introductionmentioning

confidence: 99%

On the short-term temporal variations of GNSS receiver differential phase biases

Zhang

Teunissen

Yuan

2016

J Geod

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Abstract. As a first step towards studying the ionosphere with the Global Navigation Satellite System (GNSS), leveling the phase to the code geometry-free observations on an arc-by-arc basis yields the ionospheric observables, interpreted as a combination of slant total electron content along with satellite and receiver Differential Code Biases (DCB). The leveling errors in the ionospheric observables may arise during this procedure, which, according to previous studies by other researchers, are due to the combined effects of the code multipath and the intra-day variability in the receiver DCB. In this paper we further identify the short-term temporal variations of receiver Differential Phase Biases (DPB) as another possible cause of leveling errors. Our investigation starts by the development of a method to epoch-wise estimate Between-Receiver DPB (BR-DPB) employing (inter-receiver) single-differenced, phase-only 2GNSS observations collected from a pair of receivers creating a zero or short baseline. The key issue for this method is to get rid of the possible discontinuities in the epoch-wise BR-DPB estimates, occurring when satellite assigned as pivot changes. Our numerical tests, carried out using GPS (Global Positioning System, US GNSS) and BDS (BeiDou Navigation Satellite System, Chinese GNSS) observations sampled every 30 seconds by a dedicatedly selected set of zero and short baselines, suggest two major findings. First, epoch-wise BR-DPB estimates can exhibit remarkable variability over a rather short period of time (e.g. 6 centimeters over 3 hours), thus significant from a statistical point of view. Second, a dominant factor driving this variability is the changes of ambient temperature, instead of the un-modelled phase multipath.

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“…In order to take the advantage of individual sensitivity as well as different spatial and temporal resolutions, the combination of various techniques is applied in some research groups. For example, Todorova et al (2007) combined GNSS observations and satellite altimetry data for global VTEC calculation; more recently Dettmering et al (2011) calculated regional VTEC based on a combination of space-geodetic observations including ground-based GPS observations, radio occultation data from Low Earth Orbiters (LEO), dual-frequency radar altimetry measurements and data obtained by Very Long Baseline Interferometry (VLBI).…”

Section: Introductionmentioning

confidence: 99%

Combination of Ground- and Space-Based GPS Data for the Determination of a Multi-scale Regional 4-D Ionosphere Model

Wu¹,

Limberger²,

Schmidt³

et al. 2015

International Association of Geodesy Symposia

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In this paper, we present a four-dimensional (4-D) electron density model. The vertical distribution of the electron density is described by a F2-layer Chapman function combined with a plasmasphere layer function. The F2-layer peak density NmF2 and the peak height hmF2 are spatially and temporally modeled as 3-D series expansions in terms of localized B-spline functions depending on geographical longitude, latitude and time. The corresponding unknown series coefficients are estimated by a linearized model through an appropriate parameter estimation procedure. The input data are ground-based GPS data combined with electron density profiles retrieved from ionospheric GPS radio occultation measurements onboard the FORMOSAT-3/COSMIC, GRACE and CHAMP satellites, in order to compensate the insensitivity of the ground-based GPS data to the height parameter hmF2 as well as benefit from their different spatiotemporal resolutions. We verify our approach by measurements exemplarily over South and Central America for a selected time span during a solar minimum day 2008-07-01. Based on the B-spline method, we demonstrate an effective data compression by applying a multi-scale representation for the estimated coefficients derived from wavelet analysis. IntroductionIt is well known that the ionospheric delay is the most important error source for Global Navigation Satellite Systems (GNSS) such as the Global Positioning System (GPS). In contrast to dual-frequency GPS users, single frequency

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Combination of different space-geodetic observations for regional ionosphere modeling

Cited by 66 publications

References 16 publications

Regional representation of F2 Chapman parameters based on electron density profiles

Regional representation of F2 Chapman parameters based on electron density profiles

On the short-term temporal variations of GNSS receiver differential phase biases

Combination of Ground- and Space-Based GPS Data for the Determination of a Multi-scale Regional 4-D Ionosphere Model

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