MAJIS infrared performances during the JUICE 2024 Earth fly-by: comparisons with IASI measurements and detection of atmospheric trace species
7 affiliations
- 1Laboratoire de Meteorologie Dynamique, LMD-IPSL, CNRS, Sorbonne Université, Université PSL, Institut Polytechnique, Paris, France
- 2LIRA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, 92195 Meudon CEDEX, France
- 3IAS, CNRS, Université Paris-Saclay, 91405 Orsay CEDEX, France
- 4Université Paris Cité, Institut de physique du globe de Paris (IPGP), CNRS, Paris, France
- 5School of Physics and Astronomy, University of Leicester, Leicester, UK
- 6Istituto Nazionale di Astrofisica – Istituto di Astrofisica e Planetologia Spaziali (INAF-IAPS), 00133, Roma, Italy
- 7Istituto Nazionale di Astrofisica – Astronomical Observatory of Padova, 35122, Padova, Italy
Abstract
The JUpiter ICy moons Explorer spacecraft (JUICE) successfully performed a Lunar and Earth gravity assist maneuver on 19 and 20 August 2024, which provided an excellent opportunity to test its instruments before its arrival at Jupiter in 2031. Here we focus on the evaluation of the performances of the infrared channel of the Moons and Jupiter Imaging Spectrometer (MAJIS) based on Earth observations acquired over part of the Pacific Ocean at tropical latitudes. We specifically compare MAJIS observations with nearly co-located ones from the Infrared Atmospheric Sounding Interferometer (IASI). The two instruments overlap in the spectral range 3.6 and 5.56 µm. After filtering out spectra contaminated by clouds or ocean glint, and corrected for a small spectral shift in MAJIS data, we find a very satisfactory agreement (within ±10 % across most of the spectral range) between the absolute radiance of the two instruments. We show that part – but not all – of the residual differences can be attributed to minor atmospheric variations (temperature and/or water vapor) between the scenes, especially when the two datasets were taken more than 2 h apart. Our best co-location case study, with IASI and MAJIS taken only 20-min apart, is used to highlight a low radiometric calibration bias for MAJIS pixels at the left edge, with an 8 % lower radiance for MAJIS compared to IASI. Conversely, we report an estimate of a +4 % positive bias at the right edge.
We then compare MAJIS to synthetic spectra generated with a radiative transfer algorithm, the OPerational version of the Automatized Atmospheric Absorption Atlas (4A/OP). The use of 4A/OP allows us to highlight the detection and give an estimate of a lower-bound sensitivity of MAJIS spectra to several trace species: methane (CH₄), nitrous oxide (N₂O), ozone (O₃) and carbon monoxide (CO). Based on the residuals between MAJIS and synthetic spectra, we estimate the signal-to-noise ratio to lie in the range 200–300, meeting nominal expectations. These excellent performances point to promising future jovian atmospheric observations.
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BibTeX
@article{guerlet2026majis,
title = {{MAJIS infrared performances during the JUICE 2024 Earth fly-by: comparisons with IASI measurements and detection of atmospheric trace species}},
author = {S. Guerlet and S. Guerlet and R. Armante and N. Lauzanne and F. Poulet and Y. Langevin and S. Rodriguez and L. Fletcher and T. Fouchet and G. Piccioni and A. Migliorini},
journal = {Annales Geophysicae},
year = {2026},
month = nov,
doi = {10.5194/angeo-44-1281-2026},
url = {https://doi.org/10.5194/angeo-44-1281-2026},
note = {CC BY},
}
RIS
TY - JOUR
TI - MAJIS infrared performances during the JUICE 2024 Earth fly-by: comparisons with IASI measurements and detection of atmospheric trace species
AU - S. Guerlet
AU - S. Guerlet
AU - R. Armante
AU - N. Lauzanne
AU - F. Poulet
AU - Y. Langevin
AU - S. Rodriguez
AU - L. Fletcher
AU - T. Fouchet
AU - G. Piccioni
AU - A. Migliorini
PY - 2026
DA - 2026/11/09
JO - Annales Geophysicae
DO - 10.5194/angeo-44-1281-2026
UR - https://doi.org/10.5194/angeo-44-1281-2026
AB - The JUpiter ICy moons Explorer spacecraft (JUICE) successfully performed a Lunar and Earth gravity assist maneuver on 19 and 20 August 2024, which provided an excellent opportunity to test its instruments before its arrival at Jupiter in 2031. Here we focus on the evaluation of the performances of the infrared channel of the Moons and Jupiter Imaging Spectrometer (MAJIS) based on Earth observations acquired over part of the Pacific Ocean at tropical latitudes. We specifically compare MAJIS observations with nearly co-located ones from the Infrared Atmospheric Sounding Interferometer (IASI). The two instruments overlap in the spectral range 3.6 and 5.56 µm. After filtering out spectra contaminated by clouds or ocean glint, and corrected for a small spectral shift in MAJIS data, we find a very satisfactory agreement (within ±10 % across most of the spectral range) between the absolute radiance of the two instruments. We show that part – but not all – of the residual differences can be attributed to minor atmospheric variations (temperature and/or water vapor) between the scenes, especially when the two datasets were taken more than 2 h apart. Our best co-location case study, with IASI and MAJIS taken only 20-min apart, is used to highlight a low radiometric calibration bias for MAJIS pixels at the left edge, with an 8 % lower radiance for MAJIS compared to IASI. Conversely, we report an estimate of a +4 % positive bias at the right edge. We then compare MAJIS to synthetic spectra generated with a radiative transfer algorithm, the OPerational version of the Automatized Atmospheric Absorption Atlas (4A/OP). The use of 4A/OP allows us to highlight the detection and give an estimate of a lower-bound sensitivity of MAJIS spectra to several trace species: methane (CH₄), nitrous oxide (N₂O), ozone (O₃) and carbon monoxide (CO). Based on the residuals between MAJIS and synthetic spectra, we estimate the signal-to-noise ratio to lie in the range 200–300, meeting nominal expectations. These excellent performances point to promising future jovian atmospheric observations.
SN - 0992-7689
SN - 1432-0576
ER -