A New Empirical Model of NmF2 Based on CHAMP, GRACE, and COSMIC Radio Occultation

Abstract

To facilitate F2-layer peak density (NmF2) modeling, a nonlinear polynomial model approach based on global NmF2 observational data from ionospheric radio occultation (IRO) measurements onboard the CHAMP, GRACE, and COSMIC satellites, is presented in this paper. We divided the globe into 63 slices from 80°S to 80°N according to geomagnetic latitude. A Nonlinear Polynomial Peak Density Model (NPPDM) was constructed by a multivariable least squares fitting to NmF2 measurements in each latitude slice and the dependencies of NmF2 on solar activity, geographical longitude, universal time, and day of year were described. The model was designed for quiet and moderate geomagnetic conditions (Ap ≤ 32). Using independent radio occultation data, quantitative analysis was made. The correlation coefficients between NPPDM predictions and IRO data were 0.91 in 2002 and 0.82 in 2005. The results show that NPPDM performs better than IRI2016 and Neustrelitz Peak Density Model (NPDM) under low solar activity, while it undergoes performance degradation under high solar activity. Using data from twelve ionosonde stations, the accuracy of NPPDM was found to be better than that of NPDM and comparable to that of IRI2016. Additionally, NPPDM can well simulate the variations and distributions of NmF2 and describe some ionospheric features, including the equatorial ionization anomaly, the mid-latitude trough, and the wavenumber-four longitudinal structure.

An Empirical Model of the Ionospheric Sporadic E Layer Based on GNSS Radio Occultation Data

“…This method has been applied to ionospheric empirical models, for example, the ionospheric electron density model (Kakinami et al, 2008), the total electron content (TEC) model (Jakowski et al, 2011), and the F2-layer peak density model (Z. Liu et al, 2019). The function of S4max was constructed using five variables as expressed below:…”

Altitudinal and Latitudinal Variations in Ionospheric Sporadic‐E Layer Obtained From FORMOSAT‐3/COSMIC Radio Occultation

“…Many scientists have also established empirical models for the climatological prediction of ionospheric weather conditions (e.g., Bilitza et al., 2017; Li et al., 2021; Liu et al., 2019b). The plasma irregularities in the F layer can severely affect long‐distance radio communication.…”

A novel neural network model of Earth’s topside ionosphere

“…In recent years, a number of ML-based electron density models in the Earth’s ionosphere have been developed 15 – 20 . Several models provide the F2-peak parameters 15 , 18 , while others reproduce three dimensional electron density distributions 16 , 17 . However, most existing ML-based models binned the data into spatial cells in terms of geographic latitude and longitude and thus do not provide continuous output 16 , 19 , 20 .…”

“…One of the most efficient ways to make use of the vast amounts of data for empirical modeling is by applying machine learning (ML) techniques. In recent years, a number of ML-based electron density models in the Earth's ionosphere have been developed [15][16][17][18][19][20] . Several models provide the F2-peak parameters 15,18 , while others reproduce three dimensional electron density OPEN 1 Helmholtz Centre Potsdam -GFZ German Research Centre for Geosciences, Potsdam, Germany.…”

“…In recent years, a number of ML-based electron density models in the Earth's ionosphere have been developed [15][16][17][18][19][20] . Several models provide the F2-peak parameters 15,18 , while others reproduce three dimensional electron density OPEN 1 Helmholtz Centre Potsdam -GFZ German Research Centre for Geosciences, Potsdam, Germany. 2 Institute of Physics and Astronomy, University of Potsdam, Potsdam, Germany.…”