Improving the Thermosphere Ionosphere in a Whole Atmosphere Model by Assimilating GOLD Disk Temperatures

Abstract

Global‐Scale Observations of Limb and Disk (GOLD) disk measurements of far ultraviolet molecular nitrogen band emissions are used to retrieve column integrated disk temperatures (Tdisk), which are representative of the lower‐and‐middle thermosphere. The present work develops a new approach to assimilate the Tdisk in the whole atmosphere community climate model with thermosphere‐ionosphere eXtension using the data assimilation research testbed ensemble adjustment Kalman filter. Nine days of data, 1–9 November 2018, are assimilated. Analysis state variables such as thermospheric effective temperature (Teff, airglow layer integrated temperature), ratio of atomic oxygen to molecular nitrogen column densities (O/N2), and column electron content are compared with a control simulation that is only constrained up to ∼50 km. It is observed that assimilation of the GOLD Tdisk improves the analysis states when compared with the control simulation. The analysis and model states, particularly, Teff, O/N2, and electron column density (ECD) are compared with their measurement counterparts for a validation of the assimilation. Teff and O/N2 are compared with GOLD Tdisk and O/N2. While, the ECD is compared with ground based total electron content measurements from global navigational satellite system receivers. Root mean square error (RMSE) improvements in Teff and O/N2 are about 10.8% and 22.6%, respectively. The RMSE improvement in analyses ECD is about 10% compared to the control simulation.

Thermospheric Temperature and Density Variability During 3–4 February 2022 Minor Geomagnetic Storm

“…The four days are chosen in such a way that the geomagnetic activity was quiet, so we excluded 29 January 2022, which was a slightly disturbed day. Also, averaging the disks over four days reduces the day‐to‐day variability and the random noise, which varied from 20 to 90 K for a particular disk image, depending on the SNR of the LBH emissions measured at that location (Laskar et al., 2022). From the differences (Δ T ) it can be noted that the values are positive over the majority of the disk on the storm day.…”

“…These results also indicate that GOLD T disk observations can be assimilated in data assimilation and forecasting models to improve the nowcasts and forecasts. Also, the GOLD data can be used to improve the empirical models, for example, MSIS2 and assimilative models, for example, Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (Laskar, Pedatella, et al., 2021; Laskar et al., 2022), and other upper atmosphere data assimilative models (Jackson et al., 2019). As the impact of geomagnetic storms varies with latitude, an elliptic satellite with a perigee at high‐latitude will have different drag compared to a low‐latitude perigee.…”

“…Therefore, for a better predictive capability of the thermospheric density and drag, which are critical for satellite traffic control, it is crucial that the impact of these storms be well understood and captured in existing whole atmosphere GCM and empirical models (Jackson et al., 2019). Whole atmosphere data assimilation using existing and upcoming ground and satellite based TI system measurements would be of help toward development of a better monitoring and predictive capability of space weather (Berger et al., 2020; Jackson et al., 2019; Laskar, Pedatella, et al., 2021; Laskar et al., 2022; Mlynczak et al., 2018).…”

“…However, the knowledge gained from currently available satellite based measurements have potential to improve results from the empirical models. Also, incorporating the current observations in a whole atmosphere assimilation and forecasting system could potentially improve the current understanding of the TI system (Laskar et al., 2022). Moreover, the altitudes lower than 200 km are below the reach of in situ satellite measurements, and remote sensing of the altitudes between 120 and 250 km has been rare (Forbes et al., 1996).…”

The Thermosphere Is a Drag: The 2022 Starlink Incident and the Threat of Geomagnetic Storms to Low Earth Orbit Space Operations

“…Another successful demonstration of technology for global-scale thermospheric monitoring is the NASA Global Observations of the Limb and Disk (GOLD) mission (Eastes et al, 2017). The GOLD team has demonstrated low-latency delivery of thermospheric temperature data to NOAA (Codrescu et al, 2020) and these data have been assimilated into the NCAR WACCM-X ITM research model (Laskar et al, 2021(Laskar et al, , 2022. By replicating the GOLD instrument on GEO satellites in a variety of LT positions, continuous low-latency delivery of thermospheric temperature and O/N 2 ratio composition data could be provided for nowcasting and assimilation into operational ITM forecasting models.…”