Constraining the global composition of D/H and 18O/16O in Martian water using SOFIA/EXES
Isotopic ratios in water vapour carry important information about the water reservoir on Mars. Localized variations in these ratios can inform us about the water cycle and surface–atmosphere exchanges. On the other hand, the global isotopic composition of the atmosphere carries the imprints of the l...
| Main Authors: | , , , , , , , , , , , , |
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| Format: | Journal article |
| Language: | English |
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Oxford University Press
2024
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| _version_ | 1826314964499955712 |
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| author | Alday, J Aoki, S DeWitt, C Montmessin, F Holmes, JA Patel, MR Mason, JP Encrenaz, T Richter, MJ Daerden, F Terada, N Irwin, PGJ Nakagawa, H |
| author_facet | Alday, J Aoki, S DeWitt, C Montmessin, F Holmes, JA Patel, MR Mason, JP Encrenaz, T Richter, MJ Daerden, F Terada, N Irwin, PGJ Nakagawa, H |
| author_sort | Alday, J |
| collection | OXFORD |
| description | Isotopic ratios in water vapour carry important information about the water reservoir on Mars. Localized variations in these ratios
can inform us about the water cycle and surface–atmosphere exchanges. On the other hand, the global isotopic composition of
the atmosphere carries the imprints of the long-term fractionation, providing crucial information about the early water reservoir
and its evolution throughout history. Here, we report the analysis of measurements of the D/H and 18O/16O isotopic ratios in
water vapour in different seasons (LS = 15◦, 127◦, 272◦, and 305◦) made with the Echelon-Cross-Echelle Spectrograph (EXES)
aboard the Stratospheric Observatory for Infrared Astronomy (SOFIA). These measurements, free of telluric absorption, provide
a unique tool for constraining the global isotopic composition of Martian water vapour. We find the maximum planetary D/H
ratio in our observations during the northern summer (D/H = 5.2 ± 0.2 with respect to the Vienna Standard Mean Ocean Water,
VSMOW) and to exhibit relatively small variations throughout the year (D/H = 5.0 ± 0.2 and 4.3 ± 0.4 VSMOW during the
northern winter and spring, respectively), which are to first order consistent though noticeably larger than the expectations from
condensation-induced fractionation. Our measurements reveal the annually averaged isotopic composition of water vapour to
be consistent with D/H = 5.0 ± 0.2 and 18O/16O = 1.09 ± 0.08 VSMOW. In addition, based on a comparison between the
SOFIA/EXES measurements and the predictions from a Global Climate Model, we estimate the D/H in the northern polar ice
cap to be ∼5 per cent larger than that in the atmospheric reservoir (D/Hice = 5.3 ± 0.3 VSMOW). |
| first_indexed | 2024-12-09T03:17:33Z |
| format | Journal article |
| id | oxford-uuid:dd380e68-e23d-4813-a014-482ba00520cc |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-12-09T03:17:33Z |
| publishDate | 2024 |
| publisher | Oxford University Press |
| record_format | dspace |
| spelling | oxford-uuid:dd380e68-e23d-4813-a014-482ba00520cc2024-10-18T13:32:25ZConstraining the global composition of D/H and 18O/16O in Martian water using SOFIA/EXESJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:dd380e68-e23d-4813-a014-482ba00520ccEnglishSymplectic ElementsOxford University Press2024Alday, JAoki, SDeWitt, CMontmessin, FHolmes, JAPatel, MRMason, JPEncrenaz, TRichter, MJDaerden, FTerada, NIrwin, PGJNakagawa, HIsotopic ratios in water vapour carry important information about the water reservoir on Mars. Localized variations in these ratios can inform us about the water cycle and surface–atmosphere exchanges. On the other hand, the global isotopic composition of the atmosphere carries the imprints of the long-term fractionation, providing crucial information about the early water reservoir and its evolution throughout history. Here, we report the analysis of measurements of the D/H and 18O/16O isotopic ratios in water vapour in different seasons (LS = 15◦, 127◦, 272◦, and 305◦) made with the Echelon-Cross-Echelle Spectrograph (EXES) aboard the Stratospheric Observatory for Infrared Astronomy (SOFIA). These measurements, free of telluric absorption, provide a unique tool for constraining the global isotopic composition of Martian water vapour. We find the maximum planetary D/H ratio in our observations during the northern summer (D/H = 5.2 ± 0.2 with respect to the Vienna Standard Mean Ocean Water, VSMOW) and to exhibit relatively small variations throughout the year (D/H = 5.0 ± 0.2 and 4.3 ± 0.4 VSMOW during the northern winter and spring, respectively), which are to first order consistent though noticeably larger than the expectations from condensation-induced fractionation. Our measurements reveal the annually averaged isotopic composition of water vapour to be consistent with D/H = 5.0 ± 0.2 and 18O/16O = 1.09 ± 0.08 VSMOW. In addition, based on a comparison between the SOFIA/EXES measurements and the predictions from a Global Climate Model, we estimate the D/H in the northern polar ice cap to be ∼5 per cent larger than that in the atmospheric reservoir (D/Hice = 5.3 ± 0.3 VSMOW). |
| spellingShingle | Alday, J Aoki, S DeWitt, C Montmessin, F Holmes, JA Patel, MR Mason, JP Encrenaz, T Richter, MJ Daerden, F Terada, N Irwin, PGJ Nakagawa, H Constraining the global composition of D/H and 18O/16O in Martian water using SOFIA/EXES |
| title | Constraining the global composition of D/H and 18O/16O in Martian water using SOFIA/EXES |
| title_full | Constraining the global composition of D/H and 18O/16O in Martian water using SOFIA/EXES |
| title_fullStr | Constraining the global composition of D/H and 18O/16O in Martian water using SOFIA/EXES |
| title_full_unstemmed | Constraining the global composition of D/H and 18O/16O in Martian water using SOFIA/EXES |
| title_short | Constraining the global composition of D/H and 18O/16O in Martian water using SOFIA/EXES |
| title_sort | constraining the global composition of d h and 18o 16o in martian water using sofia exes |
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