A real-time operational procedure for GPS TEC based reconstruction of the electron profile at a single ionosonde location

The propagation delays in GNSS, introduced by the ionosphere, can be estimated and corrected much easier if the (vertical) electron density profile is available at a given location on a real-time basis. As the theoretical ionospheric models are not sufficiently good for the purpose, actual on-line measurements immediately available should be considered. Presented is a robust procedure for real-time reconstruction of the electron density profile from concurrent GPS TEC and ionosonde measurements. On the one hand, the on-line ionosonde measurements are used primarily for the reconstruction of the bottom-side profile. On the other hand, the ionosonde data together with simultaneously-measured TEC and upper transition level information, are required and used for determination of the topside electron profile. It is important that the method provides variable topside scale height, and the crucial information for this variability comes from measurements of the oxygen-hydrogen ion transition height, where the largest change in the electron density gradient occur. The procedure is demonstrated and tested on actual GPS TEC and digital ionosonde data obtained at the Dourbes Geophysics Centre of the Royal Meteorological Institute of Belgium. At this center, a GPS receiver is collocated with a digital ionosonde, capable of producing TEC values every 15 minutes. Measurements have been conducted since 1994 and a large TEC database created for the best part of the current solar activity cycle

Evaluation of the automatic ionogram scaling for use in real-time ionospheric density profile specification: Dourbes DGS-256/ARTIST-4 performance.

<p>Statistical evaluation of the Dourbes (4.6˚E, 50.1˚N) digisonde automatic scaling of the more frequently used ionospheric parameters (foF2, foF1, foE, h’F2, h’F, h’E, and M3000F2) was performed using automatically and manually scaled data from the time period of 2002 to 2008. Automatic scaling was provided in 92% to 94% of cases for most characteristics, except for foF1 (81%). In terms of the automatic scaling accuracy, the magnitude of the residual error for foF2 and M3000F2 (automatically minus manually scaled values) varied according to local time, season, and solar activity. Although geomagnetic storms appear to affect the automatic scaling, the overall results for the influence of geomagnetic activity were inconclusive. Based on this analysis, error bounds were determined (95% probability) for each characteristic: foF2 (–0.75,+0.85), foF1(–0.25,+0.35), foE(–0.35,+0.40), h’F2(–68,+67), h’F(–38,+32), h’E(–26,+2), and M3000F2(–0.55,+0.45).</p

Real-time reconstruction of the vertical electron density distribution from GPS TEC measurements

Presented is a new operational model for real-time reconstruction of the vertical electron density distribution from concurrent GPS-based total electron content and ionosonde measurements. The model is developed on the basis of a novel approach for deducing the topside ion scale heights assuming Exponential, Epstein, or Chapman type of vertical density distribution. The required input data are submitted on-line to an operational centre where processing is carried out immediately and the electron density profile is derived. The method is suitable for use at middle and high latitude locations where ionosonde measurements are available. Several tests have been carried out and preliminary results have been presented and discussed