Open AccessImproving the real‐time ionospheric determination from GPS sites at very long distances over the equator
Author(s) -
HernándezPajares M.,
Juan J. M.,
Sanz J.,
Colombo O. L.
Publication year - 2002
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2001ja009203
Subject(s) - ionosphere , global positioning system , gnss applications , geodesy , remote sensing , equator , ambiguity resolution , total electron content , satellite , precise point positioning , geology , geodetic datum , tec , latitude , computer science , geophysics , physics , telecommunications , astronomy
As the authors have shown in previous work, the tomographic approach reduces significantly the mismodeling in the electron content determination using as data the ionosphere‐crossing radio signals of global navigation satellite systems (GNSS) such as the Global Positioning System (GPS). We present in this paper the results of a comprehensive study on the performance of an improved tomographic model of the ionosphere. This model is obtained from the GPS L1 and L2 carrier‐phase data, and it is used to estimate undifferenced and double‐differenced ionospheric corrections in real time and at very long distances between receivers (500–3000 km). The key point of the strategy is the combination of real‐time geodetic and ionospheric techniques to achieve a significant improvement in the reliability of carrier‐phase ambiguity resolution. This new approach includes also the use of smoothed pseudo‐ranges to help in ambiguity resolution. It has been tested under difficult ionospheric conditions, during four consecutive weeks in March–April 2001, at Solar Maximum, and at latitudes ranging from −40 to +40 degrees, so as to include the equatorial region. Dual‐frequency satellite altimetry from TOPEX‐Poseidon has been used to verify the accuracy of the ionospheric model over the oceans in that region.