GESA -Georreferenciacion Satelitaria- is a laboratory belonging to the Faculty of Astronomical and Geophysical Sciences of La Plata National University. It is a branch of the Astrometry Department specialized in Space Geodesy researches, covering realization of the International Terrestrial Reference Frame; tide gauges control by GPS for sea level rise studies; model Earth rotation irregularities; and EC imaging from beacon satellite observations. This talk outlines the results achieved by GESA in the last of the topics previously mentioned.
GESA developed the so-called La Plata Ionospheric Model (LPIM). It is an algorithm to retrieve TEC information from dual-frequency beacon satellite signals, based on a thin-layer ionosphere approximation and a spherical harmonics expansion for global TEC interpolation. Several systematic biases that affect GPS- and TOPEX-based TEC are also discussed in this talk.
Finally, a model to retrieve EC distribution from GPS observations is described. It uses the NeQuick ionspheric model to describe the electron density profile and GPS observations for updating the pick parameters. Comparisons between EC derived from our model and from ionozonde observations will be also presented.