Assessment of global and regional ionospheric maps over Brazil using simulated kinematic precise point positioning. 

Abstract

<p>Precise point positioning (PPP) is an available solution for one-frequency receivers if the ionosphere delay is informed during the data processing. Such information may be retrieved from the ionospheric maps, which can have a global or regional coverage. IGS has traditionally being providing them globally, throughout different analyses centers. On the other hand, regional products have been increasingly catching the interest of the scientific community.  Regional Ionosphere Maps (RIM) will use local active GNSS networks with multi-frequency receivers to model and represent the ionospheric delays. Because of the larger amount of information from a specific region, which may lack in the global products, the representation can be better and show improvements for areas where the ionosphere is more active. For the South American area, studies have been conducted using active networks. GIB (Brazilian Ionospheric Grid) was developed in 2010 and computes regional maps using GPS data from the Brazilian Continuous Monitoring Stations (RBMC). More recently (2018) the Meteorología espacial, Atmosfera terrestre, Geodesia, Geodinámica, diseño Instrumental y Astrometría (MAGGIA) made available its regional product covering the same area using GNSS data from Brazil, Uruguay and Argentina. Presently we are verging to the beginning of the next solar cycle and understanding the availability of global and regional products for ionosphere correction, and its level of accuracy will be a crucial information to be hold. In this contribution, an evaluation of four products was performed using kinematic PPP for the day 80 of 2021, of course with a reduced amount of data. The global products (CODE and GFZ) used the IGS network on its construction. A reference station from RBMC, with known coordinates was used as the ground truth to determine the accuracy of each product using a simulated PPP kinematics. with residuals and needed system transformation the accuracy and precision for each product was acquired. Overall results show that the MAGGIA product presents the best accuracy, followed by the GFZ, IGS and GIB. For this analysis it was possible to conclude that two elements play an important role when creating ionosphere maps: not only the regional characterization but also using multi constellation GNSS data will play a key role in the products quality. MAGGIA and GIB, both regional products, obtained the best and the worse results, respectively and the major difference being the use of only one GNSS constellation (GIB) and multiple GNSS constellations (MAGGIA) for its calculation.</p>