Swarm DISC Pre-Study 5.2

In this project, the possibility of using the space-based along-track Thermospheric Neutral Density (TND) estimates for generating the European Space Agency (ESA)'s Level 3 (L3) global multi-level TND data products is assessed. For this, the TND estimates along the CHAMP, GRACE, and Swarm satellites are used as observation within the sequential Calibration and Data Assimilation (C/DA) framework proposed by (Forootan et al., 2020 & 2022: doi:10.1093/gji/ggaa507 & doi:10.1038/s41598-022-05952-y).

The C/DA approach is applied to re-calibrate four key parameters of the NRLMSISE-00 model, which are most sensitive to the thermospheric neutral mass and thermospheric temperature. The model with re-calibrated parameters is called 'C/DA-NRLMSISE-00', whose outputs fit to the space-based TNDs. The C/DA-NRLMSISE-00 is able to forecast TNDs and individual neutral mass compositions at any predefined vertical level (i.e., the same vertical coverage as the NRLMSISE-00) and arbitrary spatial-temporal resolution. Therefore, the C/DA method is tested to produce level 3 (L3) TND data consistent with space-based TND estimates.

Seven periods (October 2003, July 2004, March 2008, April 2010, March 2015, September 2017, and September 2020), associated with relatively high geomagnetic activity, are selected for investigating the L3 products because most of available models represent difficulties to provide reasonable TND estimations. Independent comparisons (validations) are performed with the space-based TNDs that were not used within the C/DA framework (from CHAMP, GRACE, GOCE and Swarm missions), as well as with the outputs of other thermosphere models such as the Jacchia-Bowman 2008 (JB08) and the High Accuracy Satellite Drag Model (HASDM).

The Project Report is available for download.

Project duration: May 2022 – December 2022. Project funded by ESA via the Swarm DISC, Sub-Contract No. SW-CO-DTU-GS-030.