Retrieval of water vapor column abundance and aerosol properties from ChemCam passive sky spectroscopy

Timothy H. McConnochie; Michael D. Smith; Michael J. Wolff; Steve Bender; Mark Lemmon; Roger C. Wiens; Sylvestre Maurice; Olivier Gasnault; Jeremie Lasue; Pierre Yves Meslin; Ari Matti Harri; Maria Genzer; Osku Kemppinen; Germán M. Martínez; Lauren DeFlores; Diana Blaney; Jeffrey R. Johnson; James F. Bell

doi:10.1016/j.icarus.2017.10.043

Retrieval of water vapor column abundance and aerosol properties from ChemCam passive sky spectroscopy

Timothy H. McConnochie, Michael D. Smith, Michael J. Wolff, Steve Bender, Mark Lemmon, Roger C. Wiens, Sylvestre Maurice, Olivier Gasnault, Jeremie Lasue, Pierre Yves Meslin, Ari Matti Harri, Maria Genzer, Osku Kemppinen, Germán M. Martínez, Lauren DeFlores, Diana Blaney, Jeffrey R. Johnson, James F. Bell

Earth and Space Exploration, School of (SESE)

Research output: Contribution to journal › Article › peer-review

45 Scopus citations

Abstract

We derive water vapor column abundances and aerosol properties from Mars Science Laboratory (MSL) ChemCam passive mode observations of scattered sky light. This paper covers the methodology and initial results for water vapor and also provides preliminary results for aerosols. The data set presented here includes the results of 113 observations spanning from Mars Year 31 L_s = 291° (March 30, 2013) to Mars Year 33 L_s= 127° (March 24, 2016). Each ChemCam passive sky observation acquires spectra at two different elevation angles. We fit these spectra with a discrete-ordinates multiple scattering radiative transfer model, using the correlated-k approximation for gas absorption bands. The retrieval proceeds by first fitting the continuum of the ratio of the two elevation angles to solve for aerosol properties, and then fitting the continuum-removed ratio to solve for gas abundances. The final step of the retrieval makes use of the observed CO₂ absorptions and the known CO₂ abundance to correct the retrieved water vapor abundance for the effects of the vertical distribution of scattering aerosols and to derive an aerosol scale height parameter. Our water vapor results give water vapor column abundance with a precision of ±0.6 precipitable microns and systematic errors no larger than ±0.3 precipitable microns, assuming uniform vertical mixing. The ChemCam-retrieved water abundances show, with only a few exceptions, the same seasonal behavior and the same timing of seasonal minima and maxima as the TES, CRISM, and REMS-H data sets that we compare them to. However ChemCam-retrieved water abundances are generally lower than zonal and regional scale from-orbit water vapor data, while at the same time being significantly larger than pre-dawn REMS-H abundances. Pending further analysis of REMS-H volume mixing ratio uncertainties, the differences between ChemCam and REMS-H pre-dawn mixing ratios appear to be much too large to be explained by large scale circulations and thus they tend to support the hypothesis of substantial diurnal interactions of water vapor with the surface. Our preliminary aerosol results, meanwhile, show the expected seasonal pattern in dust particle size but also indicate a surprising interannual increase in water–ice cloud opacities.

Original language	English (US)
Pages (from-to)	294-326
Number of pages	33
Journal	Icarus
Volume	307
DOIs	https://doi.org/10.1016/j.icarus.2017.10.043
State	Published - Jun 2018

Keywords

Atmosphere
Mars
Radiative transfer
Spectroscopy

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1016/j.icarus.2017.10.043

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McConnochie, T. H., Smith, M. D., Wolff, M. J., Bender, S., Lemmon, M., Wiens, R. C., Maurice, S., Gasnault, O., Lasue, J., Meslin, P. Y., Harri, A. M., Genzer, M., Kemppinen, O., Martínez, G. M., DeFlores, L., Blaney, D., Johnson, J. R., & Bell, J. F. (2018). Retrieval of water vapor column abundance and aerosol properties from ChemCam passive sky spectroscopy. Icarus, 307, 294-326. https://doi.org/10.1016/j.icarus.2017.10.043

McConnochie, TH, Smith, MD, Wolff, MJ, Bender, S, Lemmon, M, Wiens, RC, Maurice, S, Gasnault, O, Lasue, J, Meslin, PY, Harri, AM, Genzer, M, Kemppinen, O, Martínez, GM, DeFlores, L, Blaney, D, Johnson, JR & Bell, JF 2018, 'Retrieval of water vapor column abundance and aerosol properties from ChemCam passive sky spectroscopy', Icarus, vol. 307, pp. 294-326. https://doi.org/10.1016/j.icarus.2017.10.043

@article{178c29ee9379437bb4a085effaa3320e,

title = "Retrieval of water vapor column abundance and aerosol properties from ChemCam passive sky spectroscopy",

abstract = "We derive water vapor column abundances and aerosol properties from Mars Science Laboratory (MSL) ChemCam passive mode observations of scattered sky light. This paper covers the methodology and initial results for water vapor and also provides preliminary results for aerosols. The data set presented here includes the results of 113 observations spanning from Mars Year 31 Ls = 291° (March 30, 2013) to Mars Year 33 Ls= 127° (March 24, 2016). Each ChemCam passive sky observation acquires spectra at two different elevation angles. We fit these spectra with a discrete-ordinates multiple scattering radiative transfer model, using the correlated-k approximation for gas absorption bands. The retrieval proceeds by first fitting the continuum of the ratio of the two elevation angles to solve for aerosol properties, and then fitting the continuum-removed ratio to solve for gas abundances. The final step of the retrieval makes use of the observed CO2 absorptions and the known CO2 abundance to correct the retrieved water vapor abundance for the effects of the vertical distribution of scattering aerosols and to derive an aerosol scale height parameter. Our water vapor results give water vapor column abundance with a precision of ±0.6 precipitable microns and systematic errors no larger than ±0.3 precipitable microns, assuming uniform vertical mixing. The ChemCam-retrieved water abundances show, with only a few exceptions, the same seasonal behavior and the same timing of seasonal minima and maxima as the TES, CRISM, and REMS-H data sets that we compare them to. However ChemCam-retrieved water abundances are generally lower than zonal and regional scale from-orbit water vapor data, while at the same time being significantly larger than pre-dawn REMS-H abundances. Pending further analysis of REMS-H volume mixing ratio uncertainties, the differences between ChemCam and REMS-H pre-dawn mixing ratios appear to be much too large to be explained by large scale circulations and thus they tend to support the hypothesis of substantial diurnal interactions of water vapor with the surface. Our preliminary aerosol results, meanwhile, show the expected seasonal pattern in dust particle size but also indicate a surprising interannual increase in water–ice cloud opacities.",

keywords = "Atmosphere, Mars, Radiative transfer, Spectroscopy",

author = "McConnochie, {Timothy H.} and Smith, {Michael D.} and Wolff, {Michael J.} and Steve Bender and Mark Lemmon and Wiens, {Roger C.} and Sylvestre Maurice and Olivier Gasnault and Jeremie Lasue and Meslin, {Pierre Yves} and Harri, {Ari Matti} and Maria Genzer and Osku Kemppinen and Mart{\'i}nez, {Germ{\'a}n M.} and Lauren DeFlores and Diana Blaney and Johnson, {Jeffrey R.} and Bell, {James F.}",

note = "Publisher Copyright: {\textcopyright} 2017 Elsevier Inc.",

year = "2018",

month = jun,

doi = "10.1016/j.icarus.2017.10.043",

language = "English (US)",

volume = "307",

pages = "294--326",

journal = "Icarus",

issn = "0019-1035",

publisher = "Academic Press Inc.",

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TY - JOUR

T1 - Retrieval of water vapor column abundance and aerosol properties from ChemCam passive sky spectroscopy

AU - McConnochie, Timothy H.

AU - Smith, Michael D.

AU - Wolff, Michael J.

AU - Bender, Steve

AU - Lemmon, Mark

AU - Wiens, Roger C.

AU - Maurice, Sylvestre

AU - Gasnault, Olivier

AU - Lasue, Jeremie

AU - Meslin, Pierre Yves

AU - Harri, Ari Matti

AU - Genzer, Maria

AU - Kemppinen, Osku

AU - Martínez, Germán M.

AU - DeFlores, Lauren

AU - Blaney, Diana

AU - Johnson, Jeffrey R.

AU - Bell, James F.

PY - 2018/6

Y1 - 2018/6

N2 - We derive water vapor column abundances and aerosol properties from Mars Science Laboratory (MSL) ChemCam passive mode observations of scattered sky light. This paper covers the methodology and initial results for water vapor and also provides preliminary results for aerosols. The data set presented here includes the results of 113 observations spanning from Mars Year 31 Ls = 291° (March 30, 2013) to Mars Year 33 Ls= 127° (March 24, 2016). Each ChemCam passive sky observation acquires spectra at two different elevation angles. We fit these spectra with a discrete-ordinates multiple scattering radiative transfer model, using the correlated-k approximation for gas absorption bands. The retrieval proceeds by first fitting the continuum of the ratio of the two elevation angles to solve for aerosol properties, and then fitting the continuum-removed ratio to solve for gas abundances. The final step of the retrieval makes use of the observed CO2 absorptions and the known CO2 abundance to correct the retrieved water vapor abundance for the effects of the vertical distribution of scattering aerosols and to derive an aerosol scale height parameter. Our water vapor results give water vapor column abundance with a precision of ±0.6 precipitable microns and systematic errors no larger than ±0.3 precipitable microns, assuming uniform vertical mixing. The ChemCam-retrieved water abundances show, with only a few exceptions, the same seasonal behavior and the same timing of seasonal minima and maxima as the TES, CRISM, and REMS-H data sets that we compare them to. However ChemCam-retrieved water abundances are generally lower than zonal and regional scale from-orbit water vapor data, while at the same time being significantly larger than pre-dawn REMS-H abundances. Pending further analysis of REMS-H volume mixing ratio uncertainties, the differences between ChemCam and REMS-H pre-dawn mixing ratios appear to be much too large to be explained by large scale circulations and thus they tend to support the hypothesis of substantial diurnal interactions of water vapor with the surface. Our preliminary aerosol results, meanwhile, show the expected seasonal pattern in dust particle size but also indicate a surprising interannual increase in water–ice cloud opacities.

AB - We derive water vapor column abundances and aerosol properties from Mars Science Laboratory (MSL) ChemCam passive mode observations of scattered sky light. This paper covers the methodology and initial results for water vapor and also provides preliminary results for aerosols. The data set presented here includes the results of 113 observations spanning from Mars Year 31 Ls = 291° (March 30, 2013) to Mars Year 33 Ls= 127° (March 24, 2016). Each ChemCam passive sky observation acquires spectra at two different elevation angles. We fit these spectra with a discrete-ordinates multiple scattering radiative transfer model, using the correlated-k approximation for gas absorption bands. The retrieval proceeds by first fitting the continuum of the ratio of the two elevation angles to solve for aerosol properties, and then fitting the continuum-removed ratio to solve for gas abundances. The final step of the retrieval makes use of the observed CO2 absorptions and the known CO2 abundance to correct the retrieved water vapor abundance for the effects of the vertical distribution of scattering aerosols and to derive an aerosol scale height parameter. Our water vapor results give water vapor column abundance with a precision of ±0.6 precipitable microns and systematic errors no larger than ±0.3 precipitable microns, assuming uniform vertical mixing. The ChemCam-retrieved water abundances show, with only a few exceptions, the same seasonal behavior and the same timing of seasonal minima and maxima as the TES, CRISM, and REMS-H data sets that we compare them to. However ChemCam-retrieved water abundances are generally lower than zonal and regional scale from-orbit water vapor data, while at the same time being significantly larger than pre-dawn REMS-H abundances. Pending further analysis of REMS-H volume mixing ratio uncertainties, the differences between ChemCam and REMS-H pre-dawn mixing ratios appear to be much too large to be explained by large scale circulations and thus they tend to support the hypothesis of substantial diurnal interactions of water vapor with the surface. Our preliminary aerosol results, meanwhile, show the expected seasonal pattern in dust particle size but also indicate a surprising interannual increase in water–ice cloud opacities.

KW - Atmosphere

KW - Mars

KW - Radiative transfer

KW - Spectroscopy

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DO - 10.1016/j.icarus.2017.10.043

M3 - Article

AN - SCOPUS:85033589730

SN - 0019-1035

VL - 307

SP - 294

EP - 326

JO - Icarus

JF - Icarus

ER -

Retrieval of water vapor column abundance and aerosol properties from ChemCam passive sky spectroscopy

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