In this study, the first high-resolution regional ionospheric model over Africa and adjacent areas (-40-40 degrees N latitude, 30 degrees W-60 degrees E longitude, and 80-1,400 km in altitude) is constructed by assimilating ground-based slant total electron content (STEC) from 40 GPS (Global Positioning System) receiver stations and space-based NmF2 (ionospheric F2 peak density) data from C2 (Constellation Observing System for Meteorology, Ionosphere, and Climate-2) into the International Reference Ionosphere (IRI-2016) model. An Ionospheric Data Assimilation Four-Dimensional (IDA4D) technique was used to estimate electron densities as high as 1.5 degrees x 3 degrees in latitude and longitude, 10 km in altitude in the E and F regions, and 15 min in universal time. Two experiments were run for the following data sets: (a) GPS-STECs only and (b) GPS-STECs and NmF2s from C2 during geomagnetically quiet (6-11 May 2021) and storm periods (12-14 May 2021). The IDA4D assimilation results are validated using independent C2 control group, ionosonde, and JASON-3 observations. Results for the storm period show that experiment 2 reduces the average root-mean-square error (RMSE) of NmF2, foF2, and VTEC by 34, 31, and 34, respectively, and increases the associated correlations by 10, 14, and 2 over IRI, respectively. Using IDA4D, we observed enhancement of the northern crest equatorial ionization anomaly in the late evening that was caused by upward and northward plasma transport.
展开▼
