Scattering and Absorption Cross-sections of Atmospheric Gases in the Ultraviolet-Visible Wavelength Range (307–725 nm)

Abstract

Abstract. Accurate Rayleigh scattering and absorption cross-sections of atmospheric gases are essential for understanding the propagation of electromagnetic radiation in planetary atmospheres. Accurate extinction cross-sections are also essential for calibrating high finesse optical cavities and differential optical absorption spectroscopy and for accurate remote sensing. In this study, we measured the scattering and absorption cross-sections of carbon dioxide, nitrous oxide, sulfur hexafluoride, oxygen, and methane in the continuous wavelength range of 307–725 nm using Broadband Cavity Enhanced Spectroscopy (BBCES). The experimentally derived Rayleigh scattering cross-sections for CO2, N2O, SF6, O2, and CH4 agree with refractive index-based calculations, with a difference of 1.5 % and 1.1 %, 1.5 %, 2.9 %, and 1.4 % on average, respectively. The O2-O2 collision-induced absorption and absorption by methane are obtained with high precision at the 0.8 nm resolution of our BBCES instrument in the 307–725 nm wavelength range. New dispersion relations for N2O, SF6, and CH4 were derived using data in the UV-vis wavelength range. This study provides improved refractive index dispersion relations, n-based Rayleigh scattering cross-sections, and absorption cross-sections for these gases.

Development of a broadband cavity-enhanced absorption spectrometer for simultaneous measurements of ambient NO3, NO2, and H2O

“…These could originate from the astigmatic bias in CCD pixels and from the environmental changes (i.e., pressure and temperature) in instrumental operation conditions. In order to minimize the impacts of these accumulated errors on concentration retrievals, measured spectra were used in previous studies (Min et al, 2016;Liang et al, 2019;Barbero et al, 2020) based on the fact that the CEAS technique is widely used to characterize the wavelength-dependent light extinction properties of chemical species (Thalman and Volkamer, 2010;Axson et al, 2011;Chen and Venables, 2011; Young Kahan et al, 2012;Sheps, 2013;Thalman and Volkamer, 2013;Prakash et al, 2018;Jordan et al, 2019;He et al, 2021;Wang et al, 2022).…”

“…Based on the capability of species-specific absorption cross-section measurements by CEAS (Axson et al, 2011;Chen and Venables, 2011;Young et al, 2011Young et al, , 2014Kahan et al, 2012;Sheps, 2013;Thalman and Volkamer, 2013;Prakash et al, 2018;He et al, 2021;Wang et al, 2022), we suggest a new approach using measured H 2 O spectrum for the simultaneous quantification of NO 3 , NO 2 , and H 2 O, which is simple and efficient enough for atmospheric application. Through this paper, we present not only our newly built broadband cavity-enhanced absorption spectrometer (BBCEAS) with detailed descriptions of design and performances but also linearity test results with H 2 O in atmospherically relevant ranges.…”

New methods for the calibration of optical resonators: Integrated Calibration by means of Optical Modulation (ICOM) and Narrow Band Cavity ring-down (NB-CRD)

“…It is a characteristic property of broad-band cavity enhanced absorption spectroscopy (BB-CEAS) cavity enhanced or differential optical absorption spectroscopy (CE-DOAS) that the length of the light path L(λ) is usually strongly wavelength dependent (e.g. He et al, 2020) -for most other differential optical absorption spectroscopy (DOAS, (Platt and Stutz, 2008)) variants the light path is independent or only weakly varying with wavelength. Once L(λ) and the material properties σ i are known, conclusions about the concentrations c i can be drawn from measurements of I(λ) and I 0 (λ) as e.g.…”