The impact of assimilating COSMIC‐2 observations of electron density in WACCMX

The present study investigates the impact of assimilating electron density profiles from the Constellation Observing System for Meteorology, Ionosphere, and Climate-2 (COSMIC-2) mission in a whole atmosphere data assimilation system. The observations are assimilated into the Whole Atmosphere Community Climate Model with thermosphere-ionosphere eXtension (WACCMX) using the Data Assimilation Research Testbed (DART) ensemble adjustment Kalman filter. Assimilation of the COSMIC-2 electron density profiles during the evaluation time period of 25–30 April 2020 leads to improvement in both the 1 hr forecast and analysis electron densities in WACCMX + DART. Compared to a control experiment that does not assimilate COSMIC-2 observations, the assimilation of the COSMIC-2 electron density profiles reduces the 1 hr forecast root mean square error (RMSE) and bias with respect to COSMIC-2 observations at 300 km by 6.76% and 24.91%, respectively. Assimilation of the COSMIC-2 electron density profiles does not significantly influence the RMSE and bias with respect to ground-based Global Navigation Satellite System vertical total electron content observations. The equatorial vertical plasma drift velocity in WACCMX + DART is changed by ±5–10 ms−1 due to the assimilation of the COSMIC-2 electron density profiles, indicating that the model representation of the electrodynamics of the low latitude ionosphere are significantly impacted by the assimilation of COSMIC-2 observations.