Pre-study 5.2 for the ESA’s multi-level global thermosphere data products consistent with Swarm and GRACE(FO)

In this project, we assess the possibility of using the space-based along-track Thermospheric Neutral Density (TND) estimates for generating European Space Agency (ESA)'s global multi-level TND data products. For this, the TND estimates along the CHAMP, GRACE, GRACE-FO and Swarm satellites are used as observation within the sequential Calibration and Data Assimilation (C/DA) framework proposed by (doi:10.1093/gji/ggaa507 \& doi:10.1038/s41598-022-05952-y). The C/DA is applied to re-calibrate the NRLMSISE00 model, which is called `C/DA-NRLMSISE00', and its outputs fit to the space-based TNDs. The C/DA-NRLMSISE00 is then applied to forecast TNDs and individual neutral mass compositions at any predefined vertical level (between ~100 and 600 km) and arbitrary spatial-temporal resolution. For example, we produced along-track, as well as half-hourly global TND fields with the spatial sampling of 1 degree, and on the vertical levels of 150, 250, 250, 450, and 550 km. Ten periods, associated with space weather storms, are selected for our investigations because most of available models represent difficulties to provide reasonable TND simulations. Independent comparisons (validations) are performed with the space-based TNDs that were not used within the C/DA framework, as well as with the outputs of other thermosphere models such as Jacchia-Bowman 2008 (JB2008) and the High Accuracy Satellite Drag Model (HASDM).