South American egional maps of vertical TEC computed by GESA: A service for the ionospheric community

BRUNINI C.; MEZA A.; GENDE M.; AZPILICUETA F.

ADVANCES IN SPACE RESEARCH

Elsevier

Año: 2008 vol. 42 p. 737 - 744

0273-1177

SIRGAS (Geocentric Reference Frame for the Americas) is an international enterprise of the geodetic community that aims to realizethe Terrestrial Reference Frame in the America?s countries. In order to fulfill this commitment, SIRGAS manages a network of continuouslyoperational GNSS receivers totalling around one hundred sites in the Caribbean, Central, and South American region. Althoughthe network was not planed for ionospheric studies, its potential to be used for such a purpose was recently recognized and SIRGASstarted a pilot experiment devoted to establish a regular service for computing and releasing regional vertical TEC (vTEC) maps basedon GNSS data. Since July, 2005, the GESA (Geodesia Espacial y Aeronomý´a) laboratory belonging to the Facultad de Ciencias Astrono´micas y Geofý´sicas of the Universidad Nacional de La Plata computes hourly maps of vertical Total Electron Content (vTEC) in theframework of the SIRGAS pilot experiment. These maps exploit all the GNSS data available in the South American region and are computedwith the LPIM (La Plata Ionospheric Model). LPIM implements a de-biasing procedure that improves data calibration in relationto other procedures commonly used for such purposes. After calibration, slant TEC measurements are converted to vertical and mappedusing local-time and modip latitude. The use of modip latitude smoothed the spatial variability of vTEC, especially in the South Americanlow latitude region and hence allows for a better vTEC interpolation. This contribution summarizes the results obtained by GESA inthe framework of the SIRGAS pilot experiment.