The Global Total Electron Content (GloTEC) model provides ionosphere situational awareness for users with systems affected by trans-ionospheric radio frequency propagation, such as Global Navigation Satellite System (GNSS) and satellite communications. The Total Electron Content (TEC) maps can be used to estimate the GNSS signal delay due to the ionospheric plasma between a receiver and a GNSS satellite. This delay impacts GNSS positioning and timing accuracy, especially during geomagnetic storms. GloTEC is a global 3-dimensional data assimilation system that uses a Gauss-Markov Kalman Filter to optimally estimate electron density in the ionosphere. The system ingests slant Total Electron Content (sTEC) from the ground-based GNSS receivers as well as space-based Radio Occultation (RO) sTEC. International Reference Ionosphere 2016 (IRI-2016), driven by the real-time F10.7 index, is used as a background model both as an a-prior state and to propagate the state forward between assimilation. Results using a new experimental CONOPS are shown, including a version with commercial radio occultation data from PlanetiQ.
New CONOPS with operational data
New CONOPS with operational and PlanetIQ data
NetCDF Files
NetCDF Files
The current operational GloTEC CONOPS uses a 10-minute cadence, 15-minute latency, and a 10-minute observation window for both ground-based and RO observations, centered on the analysis tag time. The current operational CONOPS with 15-minute latency prevents the usage of most of the RO data due to the data latency. To improve model accuracy through ingesting more RO measurements, the new experimental CONOPS configuration shown on this page retains the 10-minute cadence but uses a 30-minute latency. Ground-based TEC is ingested over a 10-minute window, whereas RO data are ingested over an expanded 30-minute window extending from 20 minutes prior to 10 minutes after the analysis tag time. Two versions of the new experimental CONOPS are shown here. One version assimilates TEC data from ground-based receivers and COSMIC-2 radio occultation TEC data (left column). The other version uses the same ground-based and COSMIC-2 data, and adds the real-time PlanetiQ radio occultation TEC data acquired through NOAA’s Commercial Data Program (right column). The PlanetiQ RO data comes from the satellites GNOMES-4 and GNOMES-5. Both satellites are in sun-synchronous orbit. GNOMES-4 orbits at 10LT and 22LT. GNOMES-5 orbits at 11LT and 23 LT. PlanetiQ data provides polar coverage in these specific local time sectors.
Contact tzu-wei.fang@noaa.gov with questions or feedback
