Validation of Ionospheric Modeled TEC in the Equatorial Ionosphere During the 2013 March and 2021 November Geomagnetic Storms

This paper presents the validation of modeled total electron content (TEC) from fourteen ionospheric models, including empirical, physics-based, and data assimilation (DA) models, hosted by the NASA/NSF Community Coordinated Modeling Center (CCMC), NOAA Space Weather Prediction Center, and NASA Jet Propulsion Laboratory (JPL). This study aims to assess the current progress and capability of the CCMC-hosted ionospheric models in capturing the storm time ionosphere during the low and moderate solar flux years. We focus on the low-latitude ionosphere (i.e., ±40º in magnetic latitude) and compare the modeled TEC with the Madrigal TEC during the 2013 March and 2021 November storms. Multiple metrics are used to quantitatively assess the models’ accuracy, precision, association, bias, and capability in capturing the TEC changes in response to the storms. The skill score based on the metric scores is further proposed to evaluate the overall performance of ionospheric models against the reference model (International Reference Ionosphere 2016, IRI-2016). The results indicate that the DA model GloTEC and JPL GIM models show good performance in modeling the TEC and reasonably reflect the storm time TEC changes spatially and temporally. The empirical models IRI-2016 and 2020 show relatively good performance compared with the physics-based models regarding the model-data comparison; however, it is difficult to characterize the TEC changes caused by storms. The physics-based models can simulate the storm effect in spatial and temporal TEC variations better than the empirical model. The performance of ionospheric models in capturing the storm time TEC anomaly is presented and discussed.