A Computationally Efficient Method for Deriving Instantaneous F2 Layer Peak Parameters From Climatological Maps and TEC Observations

Abstract International Reference Ionosphere (IRI) and the Ionosphere‐Plasmasphere (IRI‐Plas) models describe monthly median ionospheric conditions. IRI‐Plas, unlike IRI, allows one to include instantaneous Total Electron Content observations (TEC) to adjust the median predictions. The standard IRI‐Plas generates monthly medians of foF2m, hmF2m and TECm in the global grid using CCIR coefficients. Subsequent execution corrects the initial TECm by incorporating the observed instantaneous TEC, providing instantaneous proxy foF2 and hmF2 from their median parameters, similar to the products generated by IZMIRAN and IONOLAB. In this study, we propose replacing the standard IRI‐Plas calculation of TECm with empirical median TECem derived over the previous 15 days. Selected IRI‐Plas subroutines are then executed using this input to assimilate observed daily hourly TEC, thereby producing instant proxy foF2 and hmF2. This new approach significantly reduces computation time and uses median TECem derived directly from recent observations rather than model‐generated TECm. It has been validated under diverse helio‐geophysical conditions using instantaneous Global Ionospheric Maps (GIMs) produced by the Jet Propulsion Laboratory (JPL), Universitat Politècnica de Catalunya (UPC), and Moscow State University (MSU). Validation with ionosonde data shows typical root mean square errors (RMSE) for the obtained instantaneous parameters in the range 0.4–2.0 MHz for foF2, and 31–50 km for hmF2. Comparison with target day centered medians shows that the −15d empirical median provides better climatological reference than −27d empirical median or CCIR‐based standard TECm, improving the RMSE of IRI‐Plas TEC (relative to input GIM) by up to 10‐fold.