The TOLEOS (Thermosphere Observations from Low-Earth Orbiting Satellites) project will produce thermosphere mass density observations from the accelerometer measurements of the GRACE, GRACE-FO, and CHAMP satellites. In addition, crosswind observations will be derived when the signal-to-noise ratio of the aerodynamic acceleration is sufficiently large.

The data sets will complement the already existing ones of the GOCE and Swarm missions, which can be downloaded from ESA’s archives, to arrive at the most complete multi-mission thermosphere observation data base of accelerometer-carrying satellites launched since 2000.

Since the crosswind observations are sensitive to errors in the cross-track acceleration, we strive to improve their accuracy by refining the calibration of the accelerometer data as well as enhancing the radiation pressure modelling. The observations will be thoroughly validated through comparison to empirical and physics-based models of the thermosphere and through intercomparison between the missions during conjunctions such as crossover that are very close in time and alignments of the orbital planes. The conjunctions will be identified in a separate data product, which will be useful not only for validation, but also for scientific analysis.

Project duration: June 2021 – July 2022.

This project is funded by ESA via the Swarm DISC, Sub-Contract No. SW-CO-DTU-GS-129.

Documentation

• Swarm TOLEOS product description
• Swarm TOLEOS processing algorithm description 
• Swarm TOLEOS validation report