Reevaluating the Use of O2 a1Δg Band in Spaceborne Remote Sensing of Greenhouse Gases

Sun, Kang; Gordon, Iouli E.; Sioris, Christopher E.; Liu, Xueliang; Chance, K.; Wofsy, Steven C.

doi:10.1029/2018gl077823

Cited by 19 publications

(16 citation statements)

References 60 publications

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“…For instance, the 1.27-μm band is used for ground-based air mass determination by the Total Carbon Column Observing Network (TCCON; Washenfelder et al, 2006) with the advantage of having less saturated lines and reduced line-mixing effects compared to the A-band at 0.76 μm. Recent accurate modeling of the strong mesosphere/stratosphere airglow produced by O 3 photodissociation (Bertaux et al, 2018;Sun et al, 2018) makes the 1.27-μm band now suitable for spaceborne observations. In addition to the A-band, the 1.27-μm band has been selected by CNES (2018) for the satellite mission MicroCarb, devoted to the accurate determination of CO 2 in the troposphere that should be launched by 2020 or 2021.…”

Section: Introductionmentioning

confidence: 99%

Accurate Laboratory Measurement of the O₂ Collision‐Induced Absorption Band Near 1.27 μm

2019

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The atmospheric band of O2 near 1.27 μm plays an important role in determining the air mass from ground or spaceborne atmospheric spectra. This band consists of narrow absorption lines of the anormalΔ1g−XnormalΣnormalg−3()0−00.25emtransitions superimposed to a much broader collision‐induced absorption (CIA) structure. Very accurate CIA binary coefficients, BO2−O2, BO2−N2, and BO2−air, are determined by highly sensitive cavity ring down spectroscopy from low density spectra (0.36 to 0.85 amagat) of pure oxygen and an O2/N2 mixture (20.96%/79.04%) at room temperature over the 7,513–8,466‐cm−1 region. Two cavity ring down spectrometers involving 12 distributed feedback lasers and two external cavity diode lasers were used below and above 7,920 cm−1, respectively. The measurements performed at different densities show a percent level consistency. This accuracy results from (i) a high baseline stability of the spectra, (ii) an accurate determination of the baseline using argon spectra recorded for the same densities, and (iii) a reliable removal of the local contribution of the absorption lines made easier thanks to subatmospheric pressure recordings. The retrieved binary coefficients are compared to the experimental data included in HITRAN2016 database (Maté et al., 1999, https://doi.org/10.1029/1999JD900824), to the dataset used for Total Carbon Column Observing Network spectra as well as to recent ab initio calculations. Although more accurate, the binary coefficients reported here are found in agreement with the Maté et al. measurements using high pressure Fourier transform spectroscopy. The derived value of the integrated CIA band intensity SO2−air= 1.31(3) × 10−4 cm−2 amagat−2 exceeds the corresponding Fourier transform spectroscopy value by about 3%.

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Section: Introductionmentioning

confidence: 99%

Accurate Laboratory Measurement of the O₂ Collision‐Induced Absorption Band Near 1.27 μm

2019

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“…A near-real-time stray-light correction was incorporated in the TROPOMI operational data processor by approximating the stray light by a pixel-independent far-field kernel and an additional kernel representing the main reflection. This process reduces stray-light error, thus increasing gas-column retrieval accuracy (Tol et al, 2018).…”

Section: Staebell Et Al: Spectral Calibration Of the Methaneair Instrumentmentioning

confidence: 99%

Spectral calibration of the MethaneAIR instrument

et al. 2021

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Abstract. MethaneAIR is the airborne simulator of MethaneSAT, an area-mapping satellite currently under development with the goal of locating and quantifying large anthropogenic CH4 point sources as well as diffuse emissions at the spatial scale of an oil and gas basin. Built to closely replicate the forthcoming satellite, MethaneAIR consists of two imaging spectrometers. One detects CH4 and CO2 absorption around 1.65 and 1.61 µm, respectively, while the other constrains the optical path in the atmosphere by detecting O2 absorption near 1.27 µm. The high spectral resolution and stringent retrieval accuracy requirements of greenhouse gas remote sensing in this spectral range necessitate a reliable spectral calibration. To this end, on-ground laboratory measurements were used to derive the spectral calibration of MethaneAIR, serving as a pathfinder for the future calibration of MethaneSAT. Stray light was characterized and corrected for through fast-Fourier-transform-based Van Cittert deconvolution. Wavelength registration was examined and found to be best described by a linear relationship for both bands with a precision of ∼ 0.02 spectral pixel. The instrument spectral spread function (ISSF), measured with fine wavelength steps of 0.005 nm near a series of central wavelengths across each band, was oversampled to construct the instrument spectral response function (ISRF) at each central wavelength and spatial pixel. The ISRFs were smoothed with a Savitzky–Golay filter for use in a lookup table in the retrieval algorithm. The MethaneAIR spectral calibration was evaluated through application to radiance spectra from an instrument flight over the Colorado Front Range.

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“…In many ground-based, airborne, or satellite-based remote sensing projects (Blackwell et al, 2001;Cadeddu et al, 2007;Chen et al, 2012;Crisp, 2015;Kuze et al, 2009;Rosenkranz, 2001), the O 2 60 GHz and A-band at 0.76 μm are being used extensively to provide the information on atmospheric path length and surface pressure. It was also demonstrated recently that the 1.27-μm band can also be successfully employed in remote-sensing missions (Sun et al, 2018). Since the accuracy of the retrievals relies directly on the accuracy of the spectroscopic parameters from the input line-shape information, the broadening parameters of the lines are of crucial importance to these remote-sensing missions.…”

Section: Omentioning

confidence: 99%

Introduction of Water‐Vapor Broadening Parameters and Their Temperature‐Dependent Exponents Into the HITRAN Database: Part I—CO₂, N₂O, CO, CH₄, O₂, NH₃, and H₂S

et al. 2019

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The amount of water vapor in the terrestrial atmosphere is highly variable both spatially and temporally. In the tropics it sometimes constitutes 4–5% of the atmosphere. At the same time collisional broadening of spectral lines by water vapor is much larger than that by nitrogen and oxygen. Therefore, in order to accurately characterize and model spectra of the atmospheres with significant amounts of water vapor, the line‐shape parameters for spectral lines broadened by water vapor are required. In this work, the pressure‐broadening parameters (and their temperature‐dependent exponents) due to the pressure of water vapor for spectral lines of CO2, N2O, CO, CH4, O2, NH3, and H2S from both experimental and theoretical studies were collected and carefully reviewed. A set of semiempirical models based on these collected data was proposed and then used to estimate water broadening and its temperature dependence for all transitions of selected molecules in the HITRAN2016 database.

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Reevaluating the Use of O₂ a¹Δ_g Band in Spaceborne Remote Sensing of Greenhouse Gases

Cited by 19 publications

References 60 publications

Accurate Laboratory Measurement of the O₂ Collision‐Induced Absorption Band Near 1.27 μm

Accurate Laboratory Measurement of the O₂ Collision‐Induced Absorption Band Near 1.27 μm

Spectral calibration of the MethaneAIR instrument

Introduction of Water‐Vapor Broadening Parameters and Their Temperature‐Dependent Exponents Into the HITRAN Database: Part I—CO₂, N₂O, CO, CH₄, O₂, NH₃, and H₂S

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Reevaluating the Use of O2 a1Δg Band in Spaceborne Remote Sensing of Greenhouse Gases

Cited by 19 publications

References 60 publications

Accurate Laboratory Measurement of the O2 Collision‐Induced Absorption Band Near 1.27 μm

Accurate Laboratory Measurement of the O2 Collision‐Induced Absorption Band Near 1.27 μm

Spectral calibration of the MethaneAIR instrument

Introduction of Water‐Vapor Broadening Parameters and Their Temperature‐Dependent Exponents Into the HITRAN Database: Part I—CO2, N2O, CO, CH4, O2, NH3, and H2S

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Reevaluating the Use of O₂ a¹Δ_g Band in Spaceborne Remote Sensing of Greenhouse Gases

Accurate Laboratory Measurement of the O₂ Collision‐Induced Absorption Band Near 1.27 μm

Accurate Laboratory Measurement of the O₂ Collision‐Induced Absorption Band Near 1.27 μm

Introduction of Water‐Vapor Broadening Parameters and Their Temperature‐Dependent Exponents Into the HITRAN Database: Part I—CO₂, N₂O, CO, CH₄, O₂, NH₃, and H₂S