Improving SIRGAS Ionospheric Model

Abstract

The IAG Sub-Commission 1.3b, SIRGAS (Sistema de Referencia Geocéntrico para las Américas), operates a service for computing regional ionospheric maps based on GNSS observations from its Continuously Operating Network (SIRGAS-CON). The ionospheric model used by SIRGAS (named La Plata Ionopsheric Model, LPIM), has continuously evolved from a "thin layer" simplification for computing the vTEC distribution to a formulation that approximates the electron density (ED) distributions of the E, F1, F2 and top-side ionospheric layers.This contribution presents the newest improvements in the model formulation and validates the obtained results by comparing the computed vTEC to experimental values provided by the ocean altimetry Jason 1 mission. Comparisons showed a small underestimation of the Jason 1 vTEC by about 1.3 TECu on average and rather small differences ranging from À0.5 to À3.4 TECu (at 95 % probability level). The results are encouraging given that comparisons were made in the open ocean regions (far away from the SIRGAS-CON stations).

A technique for routinely updating the ITU-R database using radio occultation electron density profiles

“…The model used to represent the electron density vertical profile used in this work is the one implemented in the La Plata Ionospheric Model (LPIM) (Brunini et al 2013a). It uses three α-Chapman layers (corresponding to the three characteristic ionospheric layers) to compute the electron density N as a function of the height h:…”

“…In Brunini et al (2013a) we described the LPIM model together with a data assimilation technique that is the basis for the data analysis procedure described in the next section. In that paper we also assessed the model performances by comparing its predictions to a dataset independent of the one assimilated into the model.…”

“…The a priori value for H F2 (i.e. : H F2 pri ) was computed from f 0 F2 pri and M 3000 F2 pri , using the empirical relation adopted by LPIM (Brunini et al 2013a), which are in accordance with the ITU-R (1997) recommendations:…”

The King Edward Point Geodetic Observatory, South Georgia, South Atlantic Ocean

“…These meteorological observations together with the IWV products will contribute an important record of atmospheric conditions for South Georgia, potentially helping to improve local weather forecasts (Shanklin et al, 2009). Of particular interest will be the GNSS observations for monitoring of the ionosphere over this region, improving both spatial and temporal density of observations useful for ionospheric models, such as the SIRGAS (Sistema de Referencia Geocéntrico para Las Américas) Ionospheric Model (Brunini et al, 2013).…”

Perfeccionamiento del Modelo Ionosférico La Plata (LPIM)

“…Otros modelos no menos importantes son el NeQuick (Nava et al, 2005) y el La Plata Ionospheric Model (LPIM; Brunini, 1998). El Modelo Ionosférico La Plata (LPIM) fue desarrollado por el Dr. Claudio Brunini hacia 1998, y es constantemente actualizado y mejorado por el grupo de Geodesia Espacial y Aeronomía (GESA) de la Facultad de Ciencias Astronómicas y Geofísicas de la Universidad Nacional de La Plata, Argentina (Brunini et al, 2005;Azpilicueta et al, 2006;Brunini et al, 2011a;Brunini et al, 2011b;Conte et al, 2011;Brunini et al, 2013a;Brunini et al, 2013b).…”