TGO-Earth radio occultation: first atmospheric profiles

Radio occultation is a well-established technique for deriving vertical profiles of atmospheric temperature, pressure, and density, as well as electron density in the ionosphere, from the bending of radio signals as they propagate through a planetary atmosphere [1]. The ExoMars Trace Gas Orbiter (TGO) provides a largely unexplored dataset of radio occultation measurements using the TGO–Earth X-band link, which is particularly well suited for probing the neutral atmosphere. A previous study [2] assessed the availability of these occultation events, demonstrating a high number of potential observations due to TGO’s low-altitude, near-circular orbit.

Building on this work, an end-to-end processing pipeline for TGO–Earth radio occultation data has been developed and applied to first occultation events. The retrieval includes Doppler residuals, bending angle derivation, and Abel inversion to obtain refractivity profiles, from which vertical profiles of neutral atmospheric density and temperature, as well as ionospheric electron density, are derived.

The successful implementation of the processing pipeline and the first retrievals represent preliminary results derived from this dataset and indicate the feasibility of deriving both neutral and ionospheric profiles from TGO–Earth radio occultation measurements. Further assessment and validation of the retrieved profiles are ongoing.

 

References:

[1] Pätzold, M., Häusler, B., Tyler, G. L., et al. 2016, Planet. Space Sci., 127, 44, "Mars Express 10 years at Mars: Observations by the Mars Express Radio Science Experiment (MaRS)"

[2] Benthaus, M., Wilson, C., and Peter, K.: TGO-Earth radio occultation: a new data source for Mars neutral atmosphere profiling, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–12 Sep 2025, EPSC-DPS2025-1408, https://doi.org/10.5194/epsc-dps2025-1408, 2025.