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CO2 photolysis and ozone formation deplete heavy oxygen in Martian CO and atomic O, enriching O3 and strengthening oxygen escape fractionation.

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2026-07-14 07:24 UTC pith:GLAJ2WKQ

load-bearing objection Solid first quantitative oxygen-isotope photochemistry for Mars that matches TGO CO profiles and shows chemical lightening of escaping O; ordinary 1D caveats, not load-bearing flaws.

arxiv 2607.11047 v1 pith:GLAJ2WKQ submitted 2026-07-13 astro-ph.EP

Oxygen isotope fractionation in the Martian atmosphere induced by CO₂ photolysis and O₃ formation

Tatsuya Yoshida , Shohei Aoki , Hiromu Nakagawa , Naoki Terada , Juan Alday , Akinori Hasebe , Yuki Nakamura , Shungo Koyama
show 3 more authors
Shotaro Sakai Ryoya Sakata Ann Carine Vandaele
This is my paper
classification astro-ph.EP
keywords Mars atmosphereoxygen isotopesCO2 photolysisozone formationphotochemical modelatmospheric escapeisotopic fractionationTrace Gas Orbiter
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

Mars' atmosphere is enriched in heavy isotopes of volatile elements, a signature of past atmospheric loss to space. Recent Trace Gas Orbiter measurements indicated that vertical oxygen isotope profiles are shaped by chemistry, not only by escape and transport, but the size of those chemical effects had not been quantified. This paper builds a one-dimensional photochemical model that includes oxygen isotope fractionation from CO2 photolysis and from ozone formation. The model shows that CO ends up depleted in heavy oxygen relative to CO2 (roughly -25 per mil in 18O and -15 per mil in 17O), mainly because of fractionation during CO2 photolysis, and that the modeled CO isotope profiles match the spacecraft data for both oxygen and carbon. At the same time ozone becomes strongly enriched in heavy oxygen while atomic oxygen becomes strongly depleted; those depletions reach the altitudes from which oxygen escapes, so the net fractionation factor for oxygen escape is larger than escape physics alone would produce. The result matters because it ties present-day chemistry to the long-term isotopic evolution of Mars and predicts that escaping oxygen should carry a measurable chemical imprint.

Core claim

CO is depleted in heavy oxygen isotopes relative to CO2 (reaching delta-18O about -25 per mil and delta-17O about -15 per mil) primarily because of isotopic fractionation during CO2 photolysis; ozone is strongly enriched (about +100 per mil and +50 per mil) while atomic oxygen is highly depleted (less than or equal to -100 per mil and -50 per mil) to compensate, and these chemical effects further reduce the heavy-isotope content of the oxygen that escapes to space.

What carries the argument

A one-dimensional photochemical model (PROTEUS) expanded to 40 species and 245 reactions that explicitly includes 17O- and 18O-bearing isotopologues, laboratory absorption cross-section differences for CO2 photolysis, and temperature-dependent rate-coefficient ratios for formation of symmetric versus asymmetric ozone.

Load-bearing premise

The model assumes that absorption cross sections of every oxygen-bearing species other than the CO2 isotopologues are identical to those of the major isotopologue, and it adopts laboratory ozone-formation rate ratios without independent Martian validation; if either premise is wrong the predicted ozone enrichment, atomic-oxygen depletion, and escape enhancement change.

What would settle it

A high-resolution mass-spectrum measurement of the 18O/16O (and preferably 17O/16O) ratio of escaping oxygen ions above roughly 160 km that does not show the additional heavy-isotope depletion predicted once chemical fractionation is included, or a laboratory redetermination of the O + O18O and 18O + O2 rate coefficients that removes the large enrichment of asymmetric ozone.

Watch this falsifier. Get emailed when new claim-graph text bears on it.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Referee Report

0 major / 5 minor

Summary. This paper develops a 1D photochemical model (PROTEUS, expanded to 40 species and 245 reactions) that includes oxygen isotopic fractionation from CO2 photolysis (using Schmidt et al. 2013 cross sections) and O3 formation (using Liu et al. 2021 rate-coefficient ratios and symmetric/asymmetric branching). It predicts that CO is depleted relative to CO2 (delta18O ~ -25 per mil, delta17O ~ -15 per mil) mainly by CO2 photolysis, that O3 is strongly enriched (delta18O ~ 100 per mil, delta17O ~ 50 per mil) while atomic O is correspondingly depleted (delta18O ≲ -100 per mil, delta17O ≲ -50 per mil), and that these chemical effects lighten the oxygen reservoir available for escape, thereby enhancing the net photochemical-escape fractionation factor. Model CO isotopic profiles (including 13C16O/12C18O) agree with TGO solar-occultation retrievals within uncertainties; sensitivity tests cover eddy diffusion, H2O abundance, solar zenith angle, and artificial non-CO2 photolysis fractionation.

Significance. If the results hold, the work supplies the first quantitative, self-consistent link between CO2-photolysis and O3-formation fractionation and the vertical oxygen-isotope profiles observed by TGO, and it shows that chemical lightening of atomic O can substantially strengthen the net oxygen-escape fractionation factor. The explicit comparison with independent TGO 13C/12C, 18O/16O and 13C16O/12C18O profiles (Fig. 7), the documented reaction network (Table A1), and the falsifiable prediction that MMX mass spectrometry should detect fractionated escaping O+ constitute clear, testable advances for Martian atmospheric evolution studies.

minor comments (5)
  1. Section 2 and Fig. 1: state explicitly that the Liu et al. (2021) O3 rate ratios and branching fractions were measured under terrestrial laboratory conditions and have not been re-validated for Martian temperatures/pressures; a one-sentence caveat would help readers gauge residual uncertainty.
  2. Section 4.3, Eq. (6): the free parameter alpha (fractional contribution of atomic O to escaping oxygen) is introduced without a preferred range or observational prior; a short discussion of plausible values (or a reference to ion-chemistry models) would strengthen the escape-fractionation estimates.
  3. Figure 7: the model curves for 18O/16O do not fully capture the upturn suggested by TGO above ~60 km; although the text notes that the discrepancy lies within error bars, a brief quantitative statement of the residual (e.g., mean offset or chi-squared) would make the agreement claim more precise.
  4. Appendix Table A1: several rate-coefficient expressions contain long products of numerical factors; a compact notation or a short note that mass-dependent scaling follows Young et al. (2014) would improve readability.
  5. Throughout: a few typographical inconsistencies appear (e.g., "resorvoir", "stanrard", mixed use of "per mil" vs. ‰); a final proof-reading pass is recommended.

Circularity Check

0 steps flagged

No significant circularity; profiles are forward-modelled from external laboratory cross-sections/rates plus fixed surface boundary conditions and then compared to independent TGO data.

full rationale

The derivation chain is a standard forward photochemical calculation. Surface δ¹⁸O/δ¹⁷O of CO₂ and H₂O are prescribed to the independent Curiosity values (Webster et al. 2013); absorption cross-sections of the CO₂ isotopologues are taken from Schmidt et al. (2013) and O₃ formation rate-coefficient ratios (including temperature-dependent branching) from Liu et al. (2021); mass-dependent scalings follow Young et al. (2014). The model then integrates the expanded reaction network (Table A1) to produce free-atmosphere vertical profiles that are compared a posteriori with TGO solar-occultation retrievals (Alday et al. 2023; Aoki et al. 2023). No parameter is fitted to the TGO data and then re-used as a “prediction”; the escape fractionation factor multiplies the model-derived surface-to-escape ratio by an external photochemical-escape factor (Fox & Hać) and a free mixing parameter α. Self-citations (PROTEUS framework, Yoshida et al. 2023 settings and carbon profiles) supply only the numerical infrastructure and a parallel carbon comparison; they do not define or force the oxygen isotopic results. Sensitivity tests (eddy diffusion, H₂O abundance, artificial non-CO₂ photolysis fractionation) further demonstrate that the headline numbers are not locked by construction. Consequently the claimed CO depletion, O₃ enrichment / atomic-O depletion, and enhanced escape fractionation are genuine model outputs, not tautologies.

Axiom & Free-Parameter Ledger

6 free parameters · 6 axioms · 0 invented entities

The central claim rests on laboratory cross sections and rate coefficients taken as given, on fixed surface boundary conditions taken from Curiosity, on a prescribed 1D eddy-diffusion and H2O profile, and on an effective mixing parameter α for the escape calculation. No new physical entities are postulated; the free parameters are standard atmospheric-model knobs whose values are either measured or varied in sensitivity tests.

free parameters (6)
  • eddy diffusion coefficient profile
    Standard profile taken from Yoshida et al. (2023); varied by ±1 order of magnitude in sensitivity tests (Fig. 4); controls homopause altitude and therefore upper-atmosphere isotope gradients.
  • surface δ18O and δ17O of CO2
    Fixed at +48‰ and +24‰ to match Curiosity (Webster et al. 2013); sets the absolute scale of all other δ values.
  • H2O number-density profile and its δ18O/δ17O
    Prescribed relative humidity 22 % below 30 km, saturation above; δ18O = +84‰, δ17O = +43‰; varied by ×10 in sensitivity (Fig. 5).
  • O escape rate at upper boundary
    Fixed at 1.2 imes10^8 cm-2 s-1 following Chaffin et al. (2017); stated to have negligible effect on isotope profiles because escape timescale is long.
  • fractional contribution α of atomic O to escaping oxygen
    Free parameter (0–1) introduced in Eq. (6) because the model lacks full ion chemistry; used to span the range of possible escape fractionation factors (Fig. 8).
  • solar zenith angle
    Fixed at 0° (overhead sun); sensitivity at 60° shown in Fig. A5; affects optical-depth altitude but not the main isotope conclusions.
axioms (6)
  • domain assumption UV absorption cross sections of CO2, CO18O and CO17O at 138–212 nm are those of Schmidt et al. (2013); all other minor-isotopologue cross sections equal the major-isotopologue values.
    Stated in Section 2; controls the magnitude of photolysis fractionation that produces the CO depletion.
  • domain assumption O3 formation rate-coefficient ratios (including temperature-dependent branching to OO18O vs O18OO) are those of Liu et al. (2021).
    Figure 1 and reactions R76–R78, R173–R175; directly produces the strong O3 enrichment and atomic-O depletion.
  • domain assumption Mass-dependent kinetic isotope effects scale as the inverse square root of reduced mass (Young et al. 2014).
    Applied to all bimolecular rates; standard approximation in atmospheric isotope chemistry.
  • domain assumption Isotope-exchange rates between O and O2 and between O and CO2 follow Gregory (2021).
    Reactions R79, R80, R96, R97 etc.; couples the atomic-O and molecular reservoirs.
  • domain assumption Steady-state 1D continuity equations with eddy + molecular diffusion adequately represent the globally averaged vertical isotope profiles.
    Core modeling framework of PROTEUS (Nakamura et al. 2023); neglects horizontal transport and diurnal/seasonal variability.
  • domain assumption Photochemical escape fractionation factors are 18fph,esc = 0.2 (Fox & Hać) and 17fph,esc = 0.47 (mass-dependent scaling).
    Used in Section 4.3 to convert surface-to-escape ratios into net escape fractionation factors.

pith-pipeline@v1.1.0-grok45 · 29163 in / 3696 out tokens · 33834 ms · 2026-07-14T07:24:30.176361+00:00 · methodology

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read the original abstract

The enrichment of heavy isotopes of volatile elements in the Martian atmosphere indicates that Mars lost a large portion of its atmosphere through escape to space. Recent atmospheric measurements by ExoMars Trace Gas Orbiter (TGO) have suggested that the vertical profiles of oxygen isotopic compositions are influenced by chemical reactions involving isotopic fractionation. However, their quantitative impacts have not yet been fully evaluated. In this study, we develop a 1D photochemical model that incorporates oxygen isotopic fractionation associated with CO$_2$ photolysis and O$_3$ formation to investigate the vertical profiles of oxygen isotopic compositions. Our calculations show that CO is depleted in heavy oxygen isotopes relative to CO$_2$, reaching $\delta ^{18}$O $\sim -25$ per mil and $\delta ^{17}$O $\sim -15$ per mil, primarily due to isotopic fractionation during CO$_2$ photolysis. The vertical profiles of oxygen and carbon isotopic compositions are in good agreement between our model and the TGO measurements. O$_3$ is strongly enriched in $^{18}$O and $^{17}$O, reaching $\delta ^{18}$O $\sim 100$ per mil and $\delta ^{17}$O $\sim 50$ per mil as a consequence of the isotopic fractionation during its formation, whereas atomic oxygen is highly depleted in the heavy oxygen isotopes with $\delta ^{18}$O $\lesssim -100$ per mil and $\delta ^{17}$O $\lesssim -50$ per mil so as to compensate for their enrichment in O$_3$. These chemical fractionation processes can deplete the heavy oxygen isotopes in species that escape from the upper atmosphere, and thereby enhance the isotopic fractionation associated with oxygen escape to space. Such fractionated isotopic compositions of escaping oxygen may be detectable by the Martian Moons eXploration (MMX) mission.

Figures

Figures reproduced from arXiv: 2607.11047 by Akinori Hasebe, Ann Carine Vandaele, Hiromu Nakagawa, Juan Alday, Naoki Terada, Ryoya Sakata, Shohei Aoki, Shotaro Sakai, Shungo Koyama, Tatsuya Yoshida, Yuki Nakamura.

Figure 1
Figure 1. Figure 1: Rate coefficients of the formation reactions of 18O-bearing ozone (upper panel) and 17O-bearing ozone (lower panel) relative to that of O3 (= 𝑘O+O2+M) as a function of temperature. The solid red lines represent the rate coefficients of the reactions between O and O 18O (or O17O), and the solid orange lines represent those of the reactions between 18O (or 17O) and O2. The dashed lines represent the branchin… view at source ↗
Figure 2
Figure 2. Figure 2: Vertical profiles of 𝛿 18O (left), 𝛿 17O (center), and Δ 17O (right) for each O-bearing species. The definitions of 𝛿 𝑗O (𝑗 = 17, 18) and Δ 17O are given in Equations (1) and (2), respectively. The dashed lines represent the fixed isotopic compositions of H2O. in Nakamura et al. (2023). We apply the solar spectrum pro￾file in the wavelength range from 0.5 to 1100 nm provided by Woods et al. (2009) to calcu… view at source ↗
Figure 3
Figure 3. Figure 3: (a) Profile of photon flux with wavelength at selected altitudes. (b) Absorption cross sections of CO2 (black), CO17O (blue), CO18O (orange), and 13CO2 (red) with wavelength. (c) Relative difference in absorption cross section between species𝑖 and CO2, defined as (𝜎𝑖/𝜎CO2 − 1) × 1000, where 𝜎𝑖 and 𝜎CO2 are the absorption cross sections of species 𝑖 and CO2, respectively (𝑖 = CO18O, CO17O, 13CO2) (Schmidt e… view at source ↗
Figure 4
Figure 4. Figure 4: Vertical profiles of 𝛿 18O (left), 𝛿 17O, and Δ 17O, comparing the results obtained with the standard eddy diffusion coefficient (solid) and with an eddy diffusion coefficient one order of magnitude smaller (dashed). The upper panels show the results of CO2, CO, O, and O3, while the lower panels show those for H2O2, OH, O2, and HO2. 0 25 50 75 100 125 150 175 200 Altitude [km] CO2 CO O O3 300 200 100 0 100… view at source ↗
Figure 5
Figure 5. Figure 5: Vertical profiles of 𝛿 18O (left), 𝛿 17O (center), and Δ 17O (right), comparing the results obtained with the standard H2O profile (solid), and with an H2O mixing ratio 10 times larger (dashed). The upper panels show the results of CO2, CO, O, and O3, while the lower panels show those for H2O2, OH, O2, and HO2 [PITH_FULL_IMAGE:figures/full_fig_p005_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: Vertical profiles of 𝛿 18O, comparing the results obtained with the standard case (solid), and with artificial isotopic fractionation during the photolysis of O3, O2, H2O, H2O2, OH, and HO2 (dashed). The absorption cross sections of 18O-bearing isotopologues are reduced by 50‰ relative to those of the major isotopologues. 0.6 0.8 1.0 1.2 1.4 1.6 1.8 18O/16O [VSMOW] 10 20 30 40 50 60 70 80 Altitude [km] Thi… view at source ↗
Figure 7
Figure 7. Figure 7: Comparison of measured isotopic profiles of CO from TGO solar occultation observations with model results. The left, center, and right panels show vertical profiles of 18O/16O in CO, 13C/12C in CO, and 13C 16O/12C 18O, respectively. The isotopic ratios are normalized to the standard reference values of Vienna Standard Mean Ocean Water (VSMOW; 18O/16O = 2.0052 × 10−3 ) and Vienna Pee Dee Belemnite (VPDB; 13… view at source ↗
Figure 8
Figure 8. Figure 8: Fractionation factor associated with oxygen escape. From top to bottom, the panels show 18 𝑓s-e, 18 𝑓ph, 17 𝑓s-e, and 17 𝑓ph. The definitions of these fractionation factors are described in Section 4.3. The horizontal axis is the fractional contribution of atomic oxygen to O-bearing escaping species, corresponding to 𝛼 in Equation (4). The solid, dashed, and dotted blue lines represent the results obtained… view at source ↗

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Works this paper leans on

59 extracted references

  1. [1]

    2019, Astronomy & Astrophysics, 630, A91

    Alday, J., Wilson, C., Irwin, P., et al. 2019, Astronomy & Astrophysics, 630, A91

    2019

  2. [2]

    F., Irwin, P

    Alday, J., Wilson, C. F., Irwin, P. G., et al. 2021, Journal of Geophysical Research: Planets, 126, e2021JE006992

    2021

  3. [3]

    R., et al

    Alday, J., Trokhimovskiy, A., Patel, M. R., et al. 2023, Nature Astronomy, 7, 867

    2023

  4. [4]

    2022, Journal of Geophysical Research: Planets, 127, e2022JE007231

    Aoki, S., Vandaele, A., Daerden, F., et al. 2022, Journal of Geophysical Research: Planets, 127, e2022JE007231

    2022

  5. [5]

    2023, The Planetary Science Journal, 4, 97

    Aoki, S., Shiobara, K., Yoshida, N., et al. 2023, The Planetary Science Journal, 4, 97

    2023

  6. [6]

    A., McFadden, J., Halekas, J

    Brain, D. A., McFadden, J., Halekas, J. S., et al. 2015, Geophysical Research Letters, 42, 9142

    2015

  7. [7]

    Brinjikji, M., & Lyons, J. R. 2021, Reviews in Mineralogy and Geochemistry, 86, 197

    2021

  8. [8]

    2015, Chemical kinetics and photochemical data for use in atmospheric studies: evaluation number 18, Tech

    Burkholder, J., Sander, S., Abbatt, J., et al. 2015, Chemical kinetics and photochemical data for use in atmospheric studies: evaluation number 18, Tech. rep., Pasadena, CA: Jet Propulsion

    2015

  9. [9]

    2017, Nature geoscience, 10, 174

    Chaffin, M., Deighan, J., Schneider, N., & Stewart, A. 2017, Nature geoscience, 10, 174

    2017

  10. [10]

    2004, Planetary and Space Science, 52, 1039

    Chassefi`ere, E., & Leblanc, F. 2004, Planetary and Space Science, 52, 1039

    2004

  11. [11]

    L., Liuzzi, G., et al

    Crismani, M., Villanueva, G. L., Liuzzi, G., et al. 2021, Journal of Geophysical Research: Planets, 126, e2021JE006878

    2021

  12. [12]

    O., Iwama, G., Shinkai, M., et al

    Danielache, S. O., Iwama, G., Shinkai, M., et al. 2023, Geochemical Journal, 57, 42

    2023

  13. [13]

    2006, Journal of Geophysical Research: Planets, 111

    Fedorova, A., Korablev, O., Bertaux, J.-L., et al. 2006, Journal of Geophysical Research: Planets, 111

    2006

  14. [14]

    L., & Ha´c, A

    Fox, J. L., & Ha´c, A. 2010, Icarus, 208, 176 10Yoshida et al

    2010

  15. [15]

    L., & Ha´c, A

    Fox, J. L., & Ha´c, A. B. 2009, Icarus, 204, 527

    2009

  16. [16]

    Q., & Marcus, R

    Gao, Y. Q., & Marcus, R. 2001, Science, 293, 259

    2001

  17. [17]

    Gregory, B. S. 2021, PhD thesis, University of St Andrews

    2021

  18. [18]

    M., Ehlmann, B

    Hu, R., Kass, D. M., Ehlmann, B. L., & Yung, Y. L. 2015, Nature communications, 6, 10003

    2015

  19. [19]

    Hu, R., & Thomas, T. B. 2022, Nature Geoscience, 15, 106

    2022

  20. [20]

    2019, Earth and Space Science, 6, 752

    Huang, C.-H., Bhattacharya, S., Hsieh, Z.-M., et al. 2019, Earth and Space Science, 6, 752

    2019

  21. [21]

    L., & Berkowitz, J

    Huestis, D. L., & Berkowitz, J. 2011, in Advances in Geosciences: Volume 25: Planetary Science (PS) (World Scientific), 229–242

    2011

  22. [22]

    V., & Babikov, D

    Ivanov, M. V., & Babikov, D. 2013, Proceedings of the National Academy of Sciences, 110, 17708

    2013

  23. [23]

    Jakosky, B. M. 1991, Icarus, 94, 14

    1991

  24. [24]

    M., Pepin, R

    Jakosky, B. M., Pepin, R. O., Johnson, R. E., & Fox, J. L. 1994, Icarus, 111, 271

    1994

  25. [25]

    M., Brain, D., Chaffin, M., et al

    Jakosky, B. M., Brain, D., Chaffin, M., et al. 2018, Icarus, 315, 146

    2018

  26. [26]

    K., Sander, R., & S¨orensen, R

    Keller-Rudek, H., Moortgat, G. K., Sander, R., & S¨orensen, R. 2013, Earth System Science Data, 5, 365

    2013

  27. [27]

    2021, The Astrophysical Journal, 912, 135

    Koyama, S., Terada, N., Nakagawa, H., Kuroda, T., & Sekine, Y. 2021, The Astrophysical Journal, 912, 135

    2021

  28. [28]

    2022, Earth, Planets and Space, 74, 12

    Kuramoto, K., Kawakatsu, Y., Fujimoto, M., et al. 2022, Earth, Planets and Space, 74, 12

    2022

  29. [29]

    2018, Icarus, 299, 443

    Kurokawa, H., Kurosawa, K., & Usui, T. 2018, Icarus, 299, 443

    2018

  30. [30]

    2004, Journal of Geophysical Research: Planets, 109

    Lef`evre, F., Lebonnois, S., Montmessin, F., & Forget, F. 2004, Journal of Geophysical Research: Planets, 109

    2004

  31. [31]

    A., Lewis, B

    Liang, M.-C., Blake, G. A., Lewis, B. R., & Yung, Y. L. 2007, Proceedings of the National Academy of Sciences, 104, 21

    2007

  32. [32]

    A., & Yung, Y

    Liang, M.-C., Blake, G. A., & Yung, Y. L. 2004, Journal of Geophysical Research: Atmospheres, 109

    2004

  33. [33]

    W., Weibel, J

    Liang, M.-C., Irion, F. W., Weibel, J. D., et al. 2006, Journal of Geophysical Research: Atmospheres, 111

    2006

  34. [34]

    2021, Proceedings of the National Academy of Sciences, 118, e2105074118

    Liu, P., Liu, J., Ji, A., et al. 2021, Proceedings of the National Academy of Sciences, 118, e2105074118

    2021

  35. [35]

    Lyons, J. R. 2001, Geophysical Research Letters, 28, 3231 —. 2024, Atmosphere, 15, 292

    2001

  36. [36]

    1987, Geophysical Research Letters, 14, 80

    Mauersberger, K. 1987, Geophysical Research Letters, 14, 80

    1987

  37. [37]

    E., Onorato, R

    Miller, C. E., Onorato, R. M., Liang, M.-C., & Yung, Y. L. 2005, Geophysical Research Letters, 32

    2005

  38. [38]

    E., & Yung, Y

    Miller, C. E., & Yung, Y. L. 2000, Journal of Geophysical Research: Atmospheres, 105, 29039

    2000

  39. [39]

    2023, Earth, Planets and Space, 75, 140 Ndengu´e, S., Madronich, S., Gatti, F., et al

    Nakamura, Y., Terada, N., Koyama, S., et al. 2023, Earth, Planets and Space, 75, 140 Ndengu´e, S., Madronich, S., Gatti, F., et al. 2014, Journal of Geophysical Research: Atmospheres, 119, 4286

    2023

  40. [40]

    2022, Earth, Planets and Space, 74, 1

    Ogohara, K., Nakagawa, H., Aoki, S., et al. 2022, Earth, Planets and Space, 74, 1

    2022

  41. [41]

    S., Fedorova, A., Trokhimovskiy, A., et al

    Olsen, K. S., Fedorova, A., Trokhimovskiy, A., et al. 2022, Journal of Geophysical Research: Planets, 127, e2022JE007213

    2022

  42. [42]

    1977, Journal of Geophysical research, 82, 4635

    Owen, T., Biemann, K., Rushneck, D., et al. 1977, Journal of Geophysical research, 82, 4635

    1977

  43. [43]

    Pepin, R. O. 1991, Icarus, 92, 2 —. 1994, Icarus, 111, 289

    1991

  44. [44]

    2006, Journal of Geophysical Research: Planets, 111

    Perrier, S., Bertaux, J.-L., Lef`evre, F., et al. 2006, Journal of Geophysical Research: Planets, 111

    2006

  45. [45]

    A., Johnson, M

    Schmidt, J. A., Johnson, M. S., & Schinke, R. 2013, Proceedings of the National Academy of Sciences, 110, 17691

    2013

  46. [46]

    2018, Journal of Geophysical Research: Planets, 123, 2939

    Slipski, M., Jakosky, B., Benna, M., et al. 2018, Journal of Geophysical Research: Planets, 123, 2939

    2018

  47. [47]

    Smith, M. D. 2002, Journal of Geophysical Research: Planets, 107, 25

    2002

  48. [48]

    H., & Heidenreich III, J

    Thiemens, M. H., & Heidenreich III, J. E. 1983, Science, 219, 1073

    1983

  49. [49]

    B., Hu, R., & Lo, D

    Thomas, T. B., Hu, R., & Lo, D. Y. 2023, The Planetary Science Journal, 4, 41

    2023

  50. [50]

    A., Johnson, M

    Ueno, Y., Schmidt, J. A., Johnson, M. S., et al. 2024, Nature Geoscience, 17, 503

    2024

  51. [51]

    R., Mahaffy, P

    Webster, C. R., Mahaffy, P. R., Flesch, G. J., et al. 2013, Science, 341, 260

    2013

  52. [52]

    N., Chamberlin, P

    Woods, T. N., Chamberlin, P. C., Harder, J. W., et al. 2009, Geophysical Research Letters, 36

    2009

  53. [53]

    2021, Earth, Planets and Space, 73, 216

    Yokota, S., Terada, N., Matsuoka, A., et al. 2021, Earth, Planets and Space, 73, 216

    2021

  54. [54]

    2025, Progress in Earth and Planetary Science, 12, 51

    Yokota, S., Matsuoka, A., Murata, N., et al. 2025, Progress in Earth and Planetary Science, 12, 51

    2025

  55. [55]

    2022, Geophysical Research Letters, 49, e2022GL098485

    Yoshida, N., Nakagawa, H., Aoki, S., et al. 2022, Geophysical Research Letters, 49, e2022GL098485

    2022

  56. [56]

    2023, The Planetary Science Journal, 4, 53

    Yoshida, T., Aoki, S., Ueno, Y., et al. 2023, The Planetary Science Journal, 4, 53

    2023

  57. [57]

    1987, Planetary and space science, 35, 1067

    Yoshino, K., Freemen, D., Esmond, J., & Parkinson, W. 1987, Planetary and space science, 35, 1067

    1987

  58. [58]

    D., Yeung, L

    Young, E. D., Yeung, L. Y., & Kohl, I. E. 2014, Geochimica et Cosmochimica Acta, 135, 102

    2014

  59. [59]

    L., DeMore, W., & Pinto, J

    Yung, Y. L., DeMore, W., & Pinto, J. P. 1991, Geophysical Research Letters, 18, 13 Oxygen isotope fractionation in the Martian atmosphere11 APPENDIX A.SUPPLEMENTAL FIGURES The fixed profiles of temperature, eddy diffusion coefficient, and H 2O number density are shown in Figure A1, A2, and A3, respectively. The calculated number density profiles are shown...

    1991