# Advances in Ionospheric Space Weather by Using FORMOSAT-7/COSMIC-2 GNSS Radio Occultations
## 5 Ionospheric Space Weather Forecast
### NOAA/Swpc  
At NOAA SWPC, the F7/C2 data are being ingested into the GloTEC. GloTEC is a novel global-scale three-dimensional electron density data assimilation scheme that makes use of a Gauss-Markov Kalman filter to optimally estimate ionospheric conditions. The software package uses modern programming languages, practices, and data ingest systems to facilitate near-real-time, as well as retrospective, electron density assimilation, TEC product generation, and dissemination. The model uses ground-based GNSS observations from hundreds of dual-frequency receivers streamed from real-time providers around the world as well as RO observations of slant TEC from the F7/C2 mission. The assimilation output from GloTEC is used to generate maps of vertical TEC, peak F-region density (NmF2), the height of NmF2 (hmF2), and TEC anomaly. The anomaly map is used to identify abnormal ionospheric conditions, such as large TEC enhancements or depletions that affect radio frequency signal propagation. The GloTEC version with only ground-based GNSS data has been in operation since late 2019 to support SWPC's TEC requirement identified by the International Civil Aviation Organization (ICAO). The latest version that includes the F7/C2 data went into operation in March 2022 to support the activities at the Space Weather Forecast Office in SWPC.  
Figure 8 shows the GloTEC TEC results with both F7/C2 or ground-based data (top), with only ground-based data (middle), and with only F7/C2 data (bottom) during a minor storm at 10:55 UT on 3 February. At this particular UT time, there was a moderate geomagnetic storm with strong southward Bz (~15) observed in the solar wind measurements. The numbers of measurements for each case distributed globally are also included in the figure. The global ray plots show the increasing ocean coverage when F7/C2 data are utilized. This result also suggests that in this case, the TEC calculation based on only F7/C2 was slightly larger than the TEC derived based only on the ground-based observations.  
Figure 9a shows the TEC difference from GloTEC with F7/C2 data and without F7/C2 data at 10:55 UT on 3 February. The ground-based GNSS data were included in both runs. Significant positive bias in the ocean region clearly demonstrated the influence of F7/C2 data in correcting the overall bias in the GloTEC algorithm. Accumulating the comparison throughout the day on 3 February, Figure 9b shows the overall positive impact caused by F7/C2 data in GloTEC at regions where there were five or more observations of the F-region combining both F7/C2 and ground-based data.  
Combining ground-based and space-based GNSS signals significantly improved the global coverage for the GloTEC technique and provided us with a better real-time specification of the ionosphere to improve our current products and services. In the near future, SWPC will be obtaining the real-time scintillation data and geolocated measurements from F7/C2. Combining the rate of TEC index (ROTI) and real-time scintillation maps created from F7/C2 measurements, it is expected to largely enhance SWPC's nowcast capability in ionospheric scintillation.  
Figure 8: GloTEC TEC in units of 10\({}^{16}\)m\({}^{-2}\) for 3 rd February 2022 at 1055 UT (**left**) and numbers of measurements (**right**) calculated based on both F7/C2 and ground-based receivers (**top**), only ground-based data (**middle**), and only F7/C2 data (**bottom**).  
Figure 9: (**a**) TEC difference provided by GloTEC with and without F7/C2 data at 10:55 UT on 3 February 2022. (**b**) Histogram of TEC bias (TECu in the x-axis) calculated from GloTEC with COSMIC-II RO data included.