Multispectrum analysis of the oxygen A-band

Drouin, Brian J.; Benner, D. Chris; Brown, Linda R.; Cich, Matthew J.; Crawford, Timothy J.; Devi, V. Malathy; Guillaume, Alexandre; Hodges, Joseph T.; Mlawer, E. J.; Robichaud, David J.; Oyafuso, Fabiano; Payne, Vivienne H.; Sung, Keeyoon; Wishnow, Edward H.; Yu, Shanshan

doi:10.1016/j.jqsrt.2016.03.037

Cited by 91 publications

(79 citation statements)

References 65 publications

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“…We use the OCO‐2 instrument line shapes (ILS) for November 2015, which are defined for each of the eight sounding positions within a frame. Atmospheric molecular absorption is determined using the same absorption coefficient (ABSCO) tables as for the v7 OCO‐2 operational product except for O 2 which has a new version OCO‐2 ABSCO v5 [ Drouin et al ., ]; this is the selected ABSCO for the v8 OCO‐2 operational products. The atmospheric profiles for the radiative transfer calculations are input on 20 pressure levels, linearly interpolated from 1 hPa to the surface.…”

Section: Methods and Datamentioning

confidence: 99%

The OCO‐2 oxygen A‐band response to liquid marine cloud properties from CALIPSO and MODIS

et al. 2017

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Spectra of reflected sunlight in the oxygen A‐band contain information about cloud properties such as cloud top pressure, optical depth, and pressure thickness. Here we show, for the first time, that high‐spectral‐resolution A‐band Orbiting Carbon Observatory‐2 (OCO‐2) spectra respond largely as simulated to the optical properties of water clouds over ocean during November 2015 (N = 184,318) using input cloud properties from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Aqua and the Cloud‐Aerosol Lidar with Orthogonal Polarization on Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). In A‐band continuum channels the standard deviation of simulated minus observed radiance is ±37%. Selecting horizontally homogeneous clouds to mitigate three‐dimensional cloud effects and collocation error with the other satellites, the standard deviation of the residuals is reduced to ±18%. Using a look‐up table developed from simulations, OCO‐2's estimated cloud top pressure for low clouds (Ptop > 680 hPa) has a standard deviation of ±61 hPa relative to CALIPSO retrievals, and bias is dependent on assumed cloud pressure thickness, with our smallest value being −5 hPa. Versus MODIS optical depth, the standard deviation is ±9.0 and the bias is −2.0, although these shrink for clouds of τ < 30. These values include collocation error between the different satellites, meaning that they place an upper bound on the OCO‐2 retrieval uncertainty. The theoretical precision limit from OCO‐2's instrumental uncertainty is shown to be ±2.4 hPa in above‐cloud path and ±0.2% in optical depth for a two‐channel retrieval. Options for retrieving cloud optical depth, cloud top pressure, and pressure thickness are discussed in the context of a formal OCO‐2 cloud property retrieval.

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Section: Methods and Datamentioning

confidence: 99%

The OCO‐2 oxygen A‐band response to liquid marine cloud properties from CALIPSO and MODIS

et al. 2017

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“…The ACOS/OCO‐2 ABSCO tables are look‐up tables of cross sections of O 2 , CO 2 , and H 2 O in cm 2 /mol units, specified at a resolution of 0.01 cm −1 at 71 pressures and 17 temperatures. The tables utilize recent improvements in the molecular line parameters of the molecules sensed by OCO‐2, including the work of Drouin et al [] for the O 2 A‐band, Benner et al [] for the 2.06 μm strong CO 2 band, and Devi et al [] for the 1.6 μm weak CO 2 band.…”

Section: Methodsmentioning

confidence: 98%

Observational evidence of 3‐D cloud effects in OCO‐2 CO₂ retrievals

et al. 2017

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The standard deviations of the distributions of Orbiting Carbon Observatory (OCO‐2) measurements of CO2 (i.e., XCO2) increase in size in the presence of clouds. XCO2 and Moderate Resolution Imaging Spectroradiometer (MODIS) radiance and cloud fields, and OCO‐2 A‐band radiances, are analyzed in order to determine if this behavior is best described as a radiance‐level retrieval artifact or by 3‐D radiative transfer effects. Observations in clear‐sky and fair weather cumulus scenes are analyzed. Scatter diagrams of XCO2 versus MODIS (and OCO‐2) radiances are presented, and averages are calculated for each scene for several radiance bins. The averages vary little in clear skies but decrease markedly for cloudy scenes as radiances increase. These decreases are consistent with an interpretative framework provided by 3‐D SHDOM radiative transfer calculations. Two 3‐D metrics, ΔXCO2 and Have, are calculated and applied. ΔXCO2 is the difference in XCO2 for the smallest and largest radiance bins. Have is a measure of the heterogeneity of the cloud radiance field. Lines of XCO2 and MODIS radiance for four target mode scenes have different slopes for clear and cloudy scenes, contrary to the radiance‐level retrieval artifact interpretation. In contrast, the graph of ΔXCO2 and MODIS Have for the various scenes has a linear correlation coefficient of 0.92, consistent with the 3‐D interpretation. Since the OCO‐2 measurement requirement is 1 ppmv, the cloudy scene XCO2 standard deviations between 1.2 and 2.6 ppmv indicate that 3‐D cloud effects add an important component to the XCO2 error budget.

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“…We also include collision induced absorption (CIA) of N 2 -N 2 , N 2 -H 2 , H 2 -H 2 and H 2 -He pairs. CIA opacities for N 2 -N 2 and N 2 -H 2 pairs were added from the HITRAN database (Borysow & Frommhold 1987;Gruszka & Borysow 1997;Samuelson et al 1997;Gustafsson & Frommhold 2001;Drouin et al 2017). In Figures 1 and 2 we show line opacities for a selection of species at a temperature of 2709 K and a pressure of 1.4 bar.…”

Section: Radiative Transfer Code Petitradtransmentioning

confidence: 99%

Atmospheric compositions and observability of nitrogen-dominated ultra-short-period super-Earths

Zilinskas

Miguel

Mollière

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We explore the chemistry and observability of nitrogen dominated atmospheres for ultra-short-period super-Earths. We base the assumption, that super-Earths could have nitrogen filled atmospheres, on observations of 55 Cnc e that favour a scenario with a high-mean-molecular-weight atmosphere. We take Titan's elemental budget as our starting point and using chemical kinetics compute a large range of possible compositions for a hot super-Earth. We use analytical temperature profiles and explore a parameter space spanning orders of magnitude in C/O & N/O ratios, while always keeping nitrogen the dominant component. We generate synthetic transmission and emission spectra and assess their potential observability with the future James Webb Space Telescope and ARIEL. Our results suggest that HCN is a strong indicator of a high C/O ratio, which is similar to what is found for H-dominated atmospheres. We find that these worlds are likely to possess C/O > 1.0, and that HCN, CN, CO should be the primary molecules to be searched for in thermal emission. For lower temperatures (T < 1500 K), we additionally find NH 3 in high N/O ratio cases, and C 2 H 4 , CH 4 in low N/O ratio cases to be strong absorbers. Depletion of hydrogen in such atmospheres would make CN, CO and NO exceptionally prominent molecules to look for in the 0.6 -5.0 µm range. Our models show that the upcoming JWST and ARIEL missions will be able to distinguish atmospheric compositions of ultra-short period super-Earths with unprecedented confidence.

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Multispectrum analysis of the oxygen A-band

Cited by 91 publications

References 65 publications

The OCO‐2 oxygen A‐band response to liquid marine cloud properties from CALIPSO and MODIS

The OCO‐2 oxygen A‐band response to liquid marine cloud properties from CALIPSO and MODIS

Observational evidence of 3‐D cloud effects in OCO‐2 CO₂ retrievals

Atmospheric compositions and observability of nitrogen-dominated ultra-short-period super-Earths

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Multispectrum analysis of the oxygen A-band

Cited by 91 publications

References 65 publications

The OCO‐2 oxygen A‐band response to liquid marine cloud properties from CALIPSO and MODIS

The OCO‐2 oxygen A‐band response to liquid marine cloud properties from CALIPSO and MODIS

Observational evidence of 3‐D cloud effects in OCO‐2 CO2 retrievals

Atmospheric compositions and observability of nitrogen-dominated ultra-short-period super-Earths

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Observational evidence of 3‐D cloud effects in OCO‐2 CO₂ retrievals