Ionosonde total electron content evaluation using International Global Navigation Satellite System Service data

Abstract

Abstract. In this work, a period of 2 years (2016–2017) of ionospheric total electron content (ITEC) from ionosondes operating in Brazil is compared to the International GNSS (Global Navigation Satellite System) Service (IGS) vertical total electron content (vTEC) data. Sounding instruments from the National Institute for Space Research (INPE) provided the ionograms used, which were filtered based on confidence score (CS) and C-Level flag evaluation. Differences between vTEC from IGS maps and ionosonde TEC were accumulated in terms of root mean squared error (RMSE). As expected, we noticed that the ITEC values provided by ionosondes are systematically underestimated, which is attributed to a limitation in the electron density modeling for the ionogram topside that considers a fixed scale height, which makes density values decay too rapidly above ∼800 km, while IGS takes in account electron density from GNSS stations up to the satellite network orbits. The topside density profiles covering the plasmasphere were re-modeled using two different approaches: an optimization of the adapted α-Chapman exponential decay that includes a transition function between the F2 layer and plasmasphere and a corrected version of the NeQuick topside formulation. The electron density integration height was extended to 20 000 km to compute TEC. Chapman parameters for the F2 layer were extracted from each ionogram, and the plasmaspheric scale height was set to 10 000 km. A criterion to optimize the proportionality coefficient used to calculate the plasmaspheric basis density was introduced in this work. The NeQuick variable scale height was calculated using empirical parameters determined with data from Swarm satellites. The mean RMSE for the whole period using adapted α-Chapman optimization reached a minimum of 5.32 TECU, that is, 23 % lower than initial ITEC errors, while for the NeQuick topside formulation the error was reduced by 27 %.

Multivariate Analysis on the Ionospheric Responses to Planetary Waves During the 2019 Antarctic SSW Event

“…Compared with the ionospheric observations at a single station, the TEC maps could provide longitudinal information of the ionospheric responses to PWs. The IGS TEC data are a well‐known and established data product that was used in numerous studies of coupling between the neutral atmosphere and the ionosphere (Klipp et al., 2020; Mannucci et al., 2009).…”

A Regional Model of Topside Ionospheric Effective Scale Heights Derived From Ionosonde and GNSS TEC

“…They found that the profiles agreed with the ISR profiles. However, the ionosonde Vertical Total Electron Content (VTEC) mostly underestimates VTEC compared with GNSS TEC, also as shown and verified by Belehaki et al (2003) and Klipp et al (2020). Liu, Le et al (2007) analyzed characteristics of the VSH and ESH (Hm) by fitting α-Chapman function to the ISR profiles.…”

“…Klipp et al. (2020) verified that the ionosonde VTEC are systematically underestimated by comparing with the International GNSS Service (IGS) VTEC data. Results in Figures 10 and 11 show that the proposed model of effective scale heights can improve the accuracy of TEC estimated by ionosonde observations.…”

Validation and Improvement of NeQuick Topside Ionospheric Formulation Using COSMIC/FORMOSAT‐3 Data

“…Klipp et al. (2020) recently applied the NeQuick‐corr method to study the comparison between the ionospheric total electron content from ionosondes and the International GNSS service vertical total electron content and reported that the error was reduced by 27%.…”

“…Therefore, we can conclude that NeQuick-corr is superior to NeQuick for representing the topside ionosphere, based on this particular RO data set under consideration. Klipp et al (2020) recently applied the NeQuick-corr method to study the comparison between the ionospheric total electron content from ionosondes and the International GNSS service vertical total electron content and reported that the error was reduced by 27%.…”