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

BRUNINI CLAUDIO; MEZA AMALIA; GENDE MAURICIO; AZPILICUETA FRANCISCO

Buenos Aires

Simposio; International Reference Ionosphere Workshop; 2006

Committee for Space Research (COSPAR)

SIRGAS (Geocentric Reference Frame for the Americas) is an international enterprise of the geodetic community that aims to realize the Terrestrial Reference Frame in the America’s countries. In order to fulfil this commitment, SIRGAS manages a network of continuously operational GNSS receivers with around one hundred sites in the Caribbean, Central and South American region. Although the network was not planed for ionospheric studies, its potentiality for such purpose was recently recognized by SIRGAS and the Project started a pilot experiment devoted to establish a regular service for computing and release regional vertical TEC maps based on GNSS data. Since July, 2005, the GESA laboratory belonging to La Plata University computes hourly maps of VTEC in the framework of the SIRGAS pilot experiment. These maps exploit all the GNSS data available in the South American region and are computed with the LPIM (La Plata Ionospheric Model) procedure. LPIM implements a de-biasing procedure that improves data calibration in relation to other procedure commonly using for such purposes. After calibration, slant TEC measurements are converted to vertical and mapped using local-time and modip latitude. The use of modip latitude smoothed the spatial variability of TEC, especially in the South American low latitude region and hence allows for a better vertical TEC interpolation. This contribution summarize the results obtained by GESA in the framework of the SIGAS pilot experiment.