scholarly journals Ground-based direct-sun DOAS and airborne MAX-DOAS measurements of the collision-induced oxygen complex, O<sub>2</sub>O<sub>2</sub>, absorption with significant pressure and temperature differences

2015 ◽  
Vol 8 (2) ◽  
pp. 793-809 ◽  
Author(s):  
E. Spinei ◽  
A. Cede ◽  
J. Herman ◽  
G. H. Mount ◽  
E. Eloranta ◽  
...  
Keyword(s):  
Cross Sections ◽  
Spectral Band ◽  
Specific Humidity ◽  
Optical Absorption Spectroscopy ◽  
Correction Factors ◽  
Absorption Cross ◽  
Atmospheric Conditions ◽  
Absorption Bands ◽  
Wide Range ◽  
Simultaneous Fitting

Abstract. The collision-induced O2 complex, O2O2, is a very important trace gas for understanding remote sensing measurements of aerosols, cloud properties and atmospheric trace gases. Many ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements of the O2O2 optical depth require correction factors of 0.75 ± 0.1 to reproduce radiative transfer modeling (RTM) results for a nearly pure Rayleigh atmosphere. One of the potential causes of this discrepancy is uncertainty in laboratory-measured O2O2 absorption cross section temperature and pressure dependencies due to difficulties in replicating atmospheric conditions in the laboratory environment. This paper presents ground-based direct-sun (DS) and airborne multi-axis (AMAX) DOAS measurements of O2O2 absorption optical depths under actual atmospheric conditions in two wavelength regions (335–390 and 435–490 nm). DS irradiance measurements were made by the Washington State University research-grade Multi-Function Differential Spectroscopy Instrument instrument from 2007 to 2014 at seven sites with significant pressure (778 to 1013 hPa) and O2O2 profile-weighted temperature (247 to 275 K) differences. Aircraft MAX-DOAS measurements were conducted by the University of Colorado (CU) AMAX-DOAS instrument on 29 January 2012 over the Southern Hemispheric subtropical Pacific Ocean. Scattered solar radiance spectra were collected at altitudes between 9 and 13.2 km, with O2O2 profile-weighted temperatures of 231 to 244 K and nearly pure Rayleigh scattering conditions. Due to the well-defined DS air-mass factors during ground-based measurements and extensively characterized atmospheric conditions during the aircraft AMAX-DOAS measurements, O2O2 "pseudo" absorption cross sections, σ, are derived from the observed optical depths and estimated O2O2 column densities. Vertical O2O2 columns are calculated from the atmospheric sounding temperature, pressure and specific humidity profiles. Based on the ground-based atmospheric DS observations, there is no pressure dependence of the O2O2 σ within the measurement errors (3%). Two data sets are combined to derive the peak σ temperature dependence of the 360 and 477 nm dimer absorption bands from 231 to 275 K. DS and AMAX-derived peak σ ( O2O2) as a function of T can be described by a quadratic function at 360 nm and linear function at 477 nm with about 9% ± 2.5% per 44 K rate. Recent laboratory-measured O2O2 cross sections by Thalman and Volkamer (2013) agree with these "DOAS apparent" peak σ( O2O2) at 233, 253 and 273 K within 3%. Changes in the O2O2 spectral band shape at colder temperatures are observed for the first time in field data. Temperature effects on spectral band shapes can introduce errors in the retrieved O2O2 column abundances if a single room temperature σ( O2O2) is used in the DOAS analysis. Simultaneous fitting of σ( O2O2) at temperatures that bracket the ambient temperature range can reduce such errors. Our results show that laboratory-measured σ( O2O2) (Hermans, 2011, at 296 K and Thalman and Volkamer, 2013) are applicable for observations over a wide range of atmospheric conditions. Column densities derived using Hermans (2011) σ at 296 K require very small correction factors (0.94 ± 0.02 at 231 K and 0.99 ± 0.02 at 275 K) to reproduce theoretically calculated slant column densities for DS and AMAX-DOAS measurements. Simultaneous fitting of σ( O2O2) at 203 and 293 K further improved the results at UV and visible wavelengths for AMAX-DOAS.

scholarly journals Direct sun and airborne MAX-DOAS measurements of the collision induced oxygen complex, O<sub>2</sub>O<sub>2</sub> absorption with significant pressure and temperature differences

2014 ◽  
Vol 7 (9) ◽  
pp. 10015-10057 ◽  
Author(s):  
E. Spinei ◽  
A. Cede ◽  
J. Herman ◽  
G. H. Mount ◽  
E. Eloranta ◽  
...  
Keyword(s):  
Cross Sections ◽  
Pressure Dependence ◽  
Spectral Band ◽  
Specific Humidity ◽  
Correction Factors ◽  
Absorption Cross ◽  
Atmospheric Conditions ◽  
Absorption Bands ◽  
Wide Range ◽  
Simultaneous Fitting

Abstract. The collision induced O2 complex, O2O2, is a very important trace gas in remote sensing measurements of aerosol and cloud properties. Some ground based MAX-DOAS measurements of O2O2 slant column density require correction factors of 0.75 ± 0.1 to reproduce radiative transfer modeling (RTM) results for a near pure Rayleigh atmosphere. One of the potential causes of this discrepancy is believed to be uncertainty in laboratory measured O2O2 absorption cross section temperature and pressure dependence, due to difficulties in replicating atmospheric conditions in the laboratory environment. This paper presents direct-sun (DS) and airborne multi-axis (AMAX) DOAS measurements of O2O2 absorption optical depths under actual Earth atmospheric conditions in two wavelength regions (335–390 nm and 435–490 nm). DS irradiance measurements were made by the research grade MFDOAS instrument from 2007–2014 at seven sites with significant pressure (778–1013 hPa) and O2O2 profile weighted temperature (247–275 K) differences. Aircraft MAX-DOAS measurements were conducted by the University of Colorado AMAX-DOAS instrument on 29 January 2012 over the Southern Hemisphere subtropical Pacific Ocean. Scattered solar radiance spectra were collected at altitudes between 9 and 13.2 km, with O2O2 profile weighted temperatures of 231–244 K, and near pure Rayleigh scattering conditions. Due to the well defined DS air mass factors and extensively characterized atmospheric conditions during the AMAX-DOAS measurements, O2O2"pseudo" absorption cross sections, σ, are derived from the observed optical depths and estimated O2O2column densities. Vertical O2O2 columns are calculated from the atmospheric sounding temperature, pressure and specific humidity profiles. Based on the atmospheric DS observations, there is no pressure dependence of the O2O2 σ, within the measurement errors (3%). The two data sets are combined to derive peak σ temperature dependence of 360 and 477 nm absorption bands from 231–275 K. DS and AMAX derived peak σ(O2O2) as a function of T can be described by a quadratic function at 360 nm and linear at 477 nm with about 9 ± 2.5% per 44 K rate. Recent laboratory measured O2O2 cross sections by Thalman and Volkamer (2013) agree with these "DOAS apparent" peak σ(O2O2) at 233 K, 253 K and 273 K within 3%. Changes in the O2O2 spectral band-shape at colder temperatures are for the first time also observed in field data. Temperature effects on spectral band shapes can introduce errors in the retrieved O2O2 column abundances if a single room temperature σ(O2O2) is used in the DOAS analysis. Simultaneous fitting of σ(O2O2) at temperatures that bracket the ambient temperature range can reduce such errors. Our results suggest that laboratory measured σ(O2O2) (Hermans et al. (2011) at 296 K and Thalman and Volkamer (2013)) are applicable for observations over a wide range of atmospheric conditions. Column densities derived using Hermans et al. (2011) σ at 296 K require very small correction factors (0.94 ± 0.02 at 231 K and 0.99 ± 0.02 at 275 K) to reproduce theoretically calculated SCDs for DS and AMAX-DOAS measurements. Simultaneous fitting of σ(O2O2) at 203 and 293 K further improved results at UV and visible wavelengths for AMAX-DOAS.

scholarly journals On the relative absorption strengths of water vapour in the blue wavelength range

2015 ◽  
Vol 8 (6) ◽  
pp. 5895-5936 ◽  
Author(s):  
J. Lampel ◽  
D. Pöhler ◽  
J. Tschritter ◽  
U. Frieß ◽  
U. Platt
Keyword(s):  
Water Vapour ◽  
Cross Sections ◽  
Spectral Region ◽  
Field Measurements ◽  
Optical Absorption Spectroscopy ◽  
Absorption Cross ◽  
Absorption Bands ◽  
Blue Wavelength ◽  
Water Vapour Absorption ◽  
Density Ratios

Abstract. In recent updates of the HITRAN water vapour H2O spectroscopic compilation covering the blue spectral region (here: 394–480 nm) significant changes for the absorption bands at 416 and 426 nm were reported. In order to investigate the consistency of the different cross-sections calculated from these compilations, H2O vapour column density ratios for different spectral intervals were retrieved from Long-path and Multi-Axis – Differential Optical Absorption Spectroscopy (DOAS) measurements. We observed a significant improvement of the DOAS evaluation when using the updated HITRAN water vapour absorption cross-sections for the calculation of the reference spectra. In particular the magnitudes of the residual spectra as well as the fit errors were reduced. However we also found that the best match between measurement and model is reached when the absorption cross-section of groups of lines are scaled by factors ranging from 0.5 and 1.9, suggesting that the HITRAN water vapour absorption compilation still needs significant corrections. For this spectral region we present correction factors for HITRAN 2009, HITRAN 2012, HITEMP and BT2 derived from field measurements. Additionally, upper limits for water vapour absorption in the UV-A range from 330–390 nm are given.

scholarly journals On the relative absorption strengths of water vapour in the blue wavelength range

2015 ◽  
Vol 8 (10) ◽  
pp. 4329-4346 ◽  
Author(s):  
J. Lampel ◽  
D. Pöhler ◽  
J. Tschritter ◽  
U. Frieß ◽  
U. Platt
Keyword(s):  
Water Vapour ◽  
Cross Sections ◽  
Spectral Region ◽  
Field Measurements ◽  
Optical Absorption Spectroscopy ◽  
Absorption Cross ◽  
Absorption Bands ◽  
Blue Wavelength ◽  
Water Vapour Absorption ◽  
Density Ratios

Abstract. In recent updates of the HITRAN water vapour H2O spectroscopic compilation covering the blue spectral region (here: 394–480 nm) significant changes for the absorption bands at 416 and 426 nm were reported. In order to investigate the consistency of the different cross-sections calculated from these compilations, H2O vapour column density ratios for different spectral intervals were retrieved from long-path and multi-axis differential optical absorption spectroscopy (DOAS) measurements. We observed a significant improvement of the DOAS evaluation when using the updated HITRAN water vapour absorption cross-sections for the calculation of the reference spectra. In particular the magnitudes of the residual spectra as well as the fit errors were reduced. However, we also found that the best match between measurement and model is reached when the absorption cross-section of groups of lines are scaled by factors ranging from 0.5 to 1.9, suggesting that the HITRAN water vapour absorption compilation still needs significant corrections. For this spectral region we present correction factors for HITRAN 2009, HITRAN 2012, HITEMP and BT2 derived from field measurements. Additionally, upper limits for water vapour absorption in the UV-A range from 330 to 390 nm are given.

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

2020 ◽  
Author(s):  
Quanfu He ◽  
Zheng Fang ◽  
Ofir Shoshamin ◽  
Steven S. Brown ◽  
Yinon Rudich
Keyword(s):  
Refractive Index ◽  
Wavelength Range ◽  
Cross Sections ◽  
Rayleigh Scattering ◽  
Dispersion Relations ◽  
Optical Absorption Spectroscopy ◽  
Absorption Cross ◽  
Atmospheric Gases ◽  
Scattering Cross ◽  
Scattering Cross Sections

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.

scholarly journals MAX-DOAS formaldehyde slant column measurements during CINDI: intercomparison and analysis improvement

2013 ◽  
Vol 6 (1) ◽  
pp. 167-185 ◽  
Author(s):  
G. Pinardi ◽  
M. Van Roozendael ◽  
N. Abuhassan ◽  
C. Adams ◽  
A. Cede ◽  
...  
Keyword(s):  
Cross Sections ◽  
Cross Correlation ◽  
Optical Absorption Spectroscopy ◽  
Integration Time ◽  
Measuring Instruments ◽  
Absorption Cross ◽  
Correlation Effects ◽  
Data Set ◽  
Random Uncertainties ◽  
Ring Effect

Abstract. We present intercomparison results for formaldehyde (HCHO) slant column measurements performed during the Cabauw Intercomparison campaign of Nitrogen Dioxide measuring Instruments (CINDI) that took place in Cabauw, the Netherlands, in summer 2009. During two months, nine atmospheric research groups simultaneously operated MAX-DOAS (MultiAXis Differential Optical Absorption Spectroscopy) instruments of various designs to record UV-visible spectra of scattered sunlight at different elevation angles that were analysed using common retrieval settings. The resulting HCHO data set was found to be highly consistent, the mean difference between instruments generally not exceeding 15% or 7.5 × 1015 molec cm−2, for all viewing elevation angles. Furthermore, a sensitivity analysis was performed to investigate the uncertainties in the HCHO slant column retrieval when varying key input parameters such as the molecular absorption cross sections, correction terms for the Ring effect or the width and position of the fitting interval. This study led to the identification of potentially important sources of errors associated with cross-correlation effects involving the Ring effect, O4, HCHO and BrO cross sections and the DOAS closure polynomial. As a result, a set of updated recommendations was formulated for HCHO slant column retrieval in the 336.5–359 nm wavelength range. To conclude, an error budget is proposed which distinguishes between systematic and random uncertainties. The total systematic error is estimated to be of the order of 20% and is dominated by uncertainties in absorption cross sections and related spectral cross-correlation effects. For a typical integration time of one minute, random uncertainties range between 5 and 30%, depending on the noise level of individual instruments.

scholarly journals New and improved infrared absorption cross sections for chlorodifluoromethane (HCFC-22)

2016 ◽  
Vol 9 (6) ◽  
pp. 2593-2601 ◽  
Author(s):  
Jeremy J. Harrison
Keyword(s):  
High Resolution ◽  
Cross Sections ◽  
Infrared Absorption ◽  
Stratospheric Ozone ◽  
Optical Path Difference ◽  
Path Difference ◽  
Montreal Protocol ◽  
Absorption Cross ◽  
Atmospheric Conditions ◽  
The One

Abstract. The most widely used hydrochlorofluorocarbon (HCFC) commercially since the 1930s has been chloro-difluoromethane, or HCFC-22, which has the undesirable effect of depleting stratospheric ozone. As this molecule is currently being phased out under the Montreal Protocol, monitoring its concentration profiles using infrared sounders crucially requires accurate laboratory spectroscopic data. This work describes new high-resolution infrared absorption cross sections of chlorodifluoromethane over the spectral range 730–1380 cm−1, determined from spectra recorded using a high-resolution Fourier transform spectrometer (Bruker IFS 125HR) and a 26 cm pathlength cell. Spectra of chlorodifluoromethane/dry synthetic air mixtures were recorded at resolutions between 0.01 and 0.03 cm−1 (calculated as 0.9/MOPD; MOPD denotes the maximum optical path difference) over a range of temperatures and pressures (7.5–762 Torr and 191–295 K) appropriate for atmospheric conditions. This new cross-section dataset improves upon the one currently available in the HITRAN (HIgh-resolution TRANsmission) and GEISA (Gestion et Etude des Informations Spectroscopiques Atmosphériques) databases; in particular it provides coverage over a wider range of pressures and temperatures, has more accurate wavenumber scales, more consistent integrated band intensities, improved signal-to-noise, is free of channel fringing, and additionally covers the ν2 and ν7 bands.

scholarly journals Fast photolysis of carbonyl nitrates from isoprene

2014 ◽  
Vol 14 (5) ◽  
pp. 2497-2508 ◽  
Author(s):  
J.-F. Müller ◽  
J. Peeters ◽  
T. Stavrakou
Keyword(s):  
Quantum Yield ◽  
Cross Sections ◽  
Organic Nitrate ◽  
Absorption Cross ◽  
Atmospheric Conditions ◽  
Oxidation Experiment ◽  
Group I ◽  
Photolysis Rates ◽  
Isoprene Oxidation ◽  
Temporal Profiles

Abstract. Photolysis is shown to be a major sink for isoprene-derived carbonyl nitrates, which constitute an important component of the total organic nitrate pool over vegetated areas. Empirical evidence from published laboratory studies on the absorption cross sections and photolysis rates of α-nitrooxy ketones suggests that the presence of the nitrate group (i) greatly enhances the absorption cross sections and (ii) facilitates dissociation to a point that the photolysis quantum yield is close to unity, with O–NO2 dissociation as a likely major channel. On this basis, we provide new recommendations for estimating the cross sections and photolysis rates of carbonyl nitrates. The newly estimated photo rates are validated using a chemical box model against measured temporal profiles of carbonyl nitrates in an isoprene oxidation experiment by Paulot et al. (2009). The comparisons for ethanal nitrate and for the sum of methacrolein- and methyl vinyl ketone nitrates strongly supports our assumptions of large cross-section enhancements and a near-unit quantum yield for these compounds. These findings have significant atmospheric implications: the photorates of key carbonyl nitrates from isoprene are estimated to be typically between ~ 3 and 20 times higher than their sink due to reaction with OH in relevant atmospheric conditions. Moreover, since the reaction is expected to release NO2, photolysis is especially effective in depleting the total organic nitrate pool.

scholarly journals Temperature dependent ozone absorption cross section spectra measured with the GOME-2 FM3 spectrometer and first application in satellite retrievals

2012 ◽  
Vol 5 (5) ◽  
pp. 7983-8015 ◽  
Author(s):  
W. Chehade ◽  
B. Gür ◽  
P. Spietz ◽  
V. Gorshelev ◽  
A. Serdyuchenko ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Absorption Cross Section ◽  
Gas Flow ◽  
Absolute Cross Section ◽  
Absorption Cross ◽  
Atmospheric Conditions ◽  
Section Data ◽  
Laboratory Setup ◽  
Ozone Column

Abstract. The Global Ozone Monitoring Experiment (GOME-2) Flight Model (FM) absorption cross section spectra of ozone were measured under representative atmospheric conditions in the laboratory setup at temperatures between 203 K and 293 K in the wavelength range of 230–790 nm at a medium spectral resolution of 0.24 to 0.54 nm. Since the exact ozone amounts were unknown in the gas flow system used, the measured ozone cross sections were required to be scaled to absolute cross section units using published literature data. The Hartley, Huggins and Chappuis bands were recorded simultaneously and their temperature dependence is in good agreement with previous studies (strong temperature effect in the Huggins band and weak in the Hartley and Chappuis bands). The overall agreement of the GOME-2 FM cross sections with the literature data is well within 3%. The total ozone column retrieved from the GOME-2/MetOp-A satellite using the new cross section data is within 1% compared to the ozone amounts retrieved routinely from GOME-2.

scholarly journals Revised temperature dependent ozone absorption cross section spectra (Bogumil et al.) measured with the sciamachy satellite spectrometer

2013 ◽  
Vol 6 (2) ◽  
pp. 2449-2481 ◽  
Author(s):  
W. Chehade ◽  
V. Gorshelev ◽  
A. Serdyuchenko ◽  
J. P. Burrows ◽  
M. Weber
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Absorption Cross Section ◽  
Total Ozone ◽  
Published Data ◽  
Absorption Cross ◽  
Atmospheric Conditions ◽  
Cross Section Data ◽  
Ozone Absorption ◽  
Section Data

Abstract. Ozone absorption cross section spectra and other trace gases had been measured using the Scanning Imaging Absorption spectroMeter for Atmospheric ChartograpHY (SCIAMACHY) satellite instrument at relevant atmospheric conditions. The measured cross sections were relative cross sections and were converted to absolute values using published data. Using the SCIAMACHY's FM cross sections as published by Bogumil et al. (2003) in the SCIAMACHY retrievals of total ozone leads to an overestimation in the total ozone by 5% compared to collocated GOME data. This work presents the procedures followed to correct the ozone cross section data as published in Bogumil et al. (2003) starting from original raw data (optical density spectra) from the original measurements. The revised data agrees well within 3% with other published ozone cross-sections and preserves the correct temperature dependence in the Hartley, Huggins, Chappuis and Wolf bands. SCIAMACHY's total ozone columns retrieved using the revised cross section data are shown to be within 1% compared to the ozone amounts retrieved routinely from SCIAMACHY.

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