Results on the assimilation of GOLD temperature and O/N2 Observations in WACCMX+DART

The Global-scale Observations of Limb and Disk (GOLD) imager scans the Earth in the far ultraviolet wavelengths. Spectral measurements from GOLD are used to retrieve column integrated thermospheric neutral temperature (Tdisk) and oxygen to molecular nitrogen column density ratio (O/N2) over about one fourth of the globe. The present investigation assesses the impact of GOLD disk temperatures and O/N2 on the Whole Atmosphere Community Climate Model with thermosphere-ionosphere eXtension (WACCMX) using Data Assimilation Research Testbed (DART) ensemble Kalman filter. Observing System Simulation experiments (OSSEs), run with and without GOLD measurements, show that assimilating the two GOLD observations improves the root mean square error (RMSE) and bias of forecast and analysis states. Assimilation of actual GOLD Tdisk observations also shows improvement when compared to independent thermosphere and ionosphere measurements. Using a Specified Dynamics WACCMX (SD-WACCMX) run as the control simulation, we found that the RMSE improvements in the analysis effective temperature and O/N2 are about 10.8% and 22.6%, respectively. Also, RMSE improvement in analysis electron column density is about 10% compared to the control simulation. Moreover, improvement in TEC RMSE is about 25% as observed from OSSE experiments that assimilated synthetic GOLD O/N2 observations. These results demonstrate that assimilation of GOLD temperature and O/N2 observations have a significant impact on the ionosphere-thermosphere model results.
The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)