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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 reprodu...
Contexts in source publication
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... spectra were analyzed in two wavelength re- gions, 335-390 and 435-490 nm, to evaluate the ∼ 360 and 477 nm O 2 O 2 absorption lines. Table 3 lists all fitting pa- rameters and laboratory-measured higher resolution trace- gas molecular absorption cross sections used in DOAS anal- yses after convolution with the MFDOAS instrument trans- fer function. All cross sections were fitted as non-differential cross sections to remove dependence on the polynomial or- der used to estimate cross-section broadband absorption. ...
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... typical 8 h flight time. A summary of analysis settings and cross sections used can be found in Table 3. One spectrum collected at 13.2 km altitude was used as a reference Fraun- hofer spectrum to analyze all data (see Table 2). ...
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... transfer calculations were performed with McArtim ( Deutschmann et al., 2011), a fully spherical Monte Carlo RTM, for 360 and 477 nm. Radiation fields were con- strained by in situ pressure, temperature, water vapor, ozone, MTP temperature profiles and stratospheric profiles of NO 2 and O 3 taken from the Real-time Air Quality Modeling Sys- tem (RAQMS) ( Piers et al., 2007 T M F : 7 J u l y 2 0 0 7 l i n e a r f i t T M F G S F C : 2 3 M a y 2 0 0 7 l i n e a r f Table 3; (b) difference between DS-measured SCD and calculated SCD * as a function of SCD * for data from (a). ...
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... REF was calculated from the DS measurements at each site in the UV and visible fitting windows using the Langley plot method. Examples of the Langley plots for the refer- ence data collected over the TMF (high-altitude unpolluted site) and GSFC (∼sea level polluted site) analyzed in 435- 490 nm, with the settings described in Table 3, are presented in Fig. 2. The linear regression analysis presented in Fig. 2 is similar at all sites and shows high correlation between the DS SCD and AMF, with R 2 of 1.000 for the visible wave- length region and better than 0.980 for the UV. The final er- ror in the SCD REF derived from the UV and visible wave- length windows was determined as 1 standard deviation of SCD REF calculated from SCDs with different DOAS fitting parameters (e.g., polynomial order, offset order, fitting win- dow boundaries). ...
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... a similar analysis as a function of SZA in the UV from the same 282-498 nm spectra was not possi- ble due to low SNR of UV irradiance at high SZA. How- ever, for UV measurements at SZA 19 • over GSFC and 42 • over WSU, the agreement between the measured and esti- mated SCD is within 3 % using settings outlined in Table 3. The OD spectral residual RMS is 2.8 × 10 −4 over GSFC and 2.7×10 −4 over WSU. ...
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Citations
... Tropospheric aerosol was assumed to be marine for both MT-DOAS and AMAX-DOAS simulations: non-absorbing Henyey-Greenstein aerosol phase function with asymmetry parameter g = 0.72 above the boundary layer and g = 0.77 in the boundary layer. The retrieval of aerosol extinction was based on reproducing O 4 signals measured by DOAS at 360 nm (Spinei et al., 2015;Volkamer et al., 2015) and utilized a layering approach. The surface was set at sea level with an albedo of 0.05 at 360 nm and 0.08 at 477 nm. ...
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... pressure, weak aerosols) on the measured photon path distribution (Ortega et al., 2016;Spinei et al., 2015;Tirpitz et al., 2021;Wagner et al., 2019; see Text S1 in Supporting Information S1). ...
Plain Language Summary
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... The O 4 SCDs' behavior with respect to SZA can be modeled using a RTM, e.g., SCIA-TRAN [52]. However, in several cases, as reported by [53], the simulated O 4 SCDs can differ (as a bias and not in the behavior) from the measured ones. For this reason, to filter the data, we decided to use only the measured O 4 SCDs. ...
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... Differential Optical Absorption Spectroscopy (DOAS) is one of the main common remote sensing techniques used to monitor atmospheric trace gases [94], from ground-based passing, airborne measurements [95], to embarked satellites such as Sciamachy [96]. The method is presented in section in ambient air [106], nitrogen dioxide [107][108][109] or HONO [109]. ...
... As the Ti:sa crystal used is 1.9 mm and the cavity length is 30 cm the positive dispersion to compensate is 120 fs . A total net negative dispersion 95 to induce to the cavity has been determined to be -150 fs . In this case the use of chirped mirror was enough to obtain -50 fs net total dispersion. ...
The atmospheric gas phase evolution is of main concern for air quality and climate evolution, as indicated in the recent IPPC Report [1]. In this context, the radical OH has been recognized as one of the key molecule in the atmosphere, participating for instance to 90 % of the atmospheric methane loss. The radical OH interactions in the atmosphere remain not fully understood, as it is very challenging to measure. To improve the understanding of the role of OH in the atmosphere, there is a need for instruments that should be sensitive, accurate, and have a fast acquisition time in the timeframe of the OH lifetime (ms). We propose to extend the already existing dual comb spectroscopy (DCS) methodology instrument from the IR [2,3] to the near UV region to take advantage of the strong absorption cross-section of OH at 308 nm. Numerical and theoretical work [4] effectively assess the feasibility of the DCS method in the UV range. This study concludes that the TiSa Kerr lens mode-locked laser source appears to be the most adapted laser source to realize DCS in the UV. The advantages of the remote sensing DCS method are multiple: it is a fast acquisition rate with similar sensitivity than the existing spectroscopic methods, it is an in-situ method, free of sampling retrieval and free of atmospheric fluctuations. A homemade DCS laser source has been fully realized in the laboratory with an original geometry. It consists in a single ring cavity laser generating two pulses trains of 100 fs. This geometry is advantageous for DCS as it allows a common noise sharing (amplitude and phase). The total mode-locked emitted output power reaches 700 mW with 5.5 W pump power, which would provide enough power to probe atmospheric molecules with UV-DCS via third harmonic generation. The first tests of the DCS experiment using our homemade laser source have been realized on Fabry-Perot (FP) and O2 molecules. We retrieved accurately the free spectral range of the FP and obtained, with high accuracy, the ro-vibrational transitions position of O2 at 760 nm. We demonstrated that the here developed single cavity laser source provides high enough relative phase stability (at least 330 ms) between the two laser emissions. These first results represent an important milestone towards atmospheric trace gases remote sensing using UV-DCS. [1] IPCC, 2021: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S. L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M. I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J. B. R. Matthews, T. K. Maycock, T. Waterfield, O. Yelekçi, R. Yu and B. Zhou (eds.)]. Cambridge University Press. In Press [2] Rieker, G. B., Giorgetta, F. R., Coddington, I., Swann, W. C., Sinclair, L. C., Cromer, C. L., ... & Newbury, N. R. (2013, November). Dual-comb spectroscopy of greenhouse gases over a 2-km outdoor path. In Optical Instrumentation for Energy and Environmental Applications (pp. ET2A-2). Optical Society of America. [3] Coburn, S., Alden, C. B., Wright, R., Cossel, K., Baumann, E., Truong, G. W., ... & Rieker, G. B. (2018). Regional trace-gas source attribution using a field-deployed dual frequency comb spectrometer. Optica, 5(4), 320-327. [4] Galtier, S., Pivard, C., & Rairoux, P. (2020). Towards DCS in the UV Spectral Range for Remote Sensing of Atmospheric Trace Gases. Remote Sensing, 12(20), 3444.
... Several 560 studies have confirmed the idea of the O 4 scaling factor and have shown that applying a SF (commonly using a value between 0.75 and 0.9) is indeed necessary (Wagner et al., 2009;Clémer et al., 2010;Irie et al., 2011;Vlemmix et al., 2015b;Wang et al., 2016;Frieß et al., 2016;Wagner et al., 2019Wagner et al., , 2021. However, other studies have not supported this requirement (Spinei et al., 2015;Ortega et al., 2016;Seyler et al., 2017;Wang et al., 2017a, b). Although the need for an O 4 scaling factor for retrieving aerosol information from MAX-DOAS measurements has been extensively discussed (Wagner 565 et al., 2019), its physical mechanism is not understood and still remains an unresolved issue. ...
In this study we focus on the retrieval of aerosol and trace gas vertical profiles from Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations for the first time over Thessaloniki, Greece. We use two independent inversion algorithms for the profile retrievals: The Mexican MAX-DOAS Fit (MMF) and the Mainz Profile Algorithm (MAPA). The former is based on the Optimal Estimation Method (OEM), while the latter follows a parameterization approach. We evaluate the performance of MMF and MAPA and we validate their retrieved products with ancillary data measured by other co-located reference instruments. We find an excellent agreement between the tropospheric column densities of NO2 retrieved by MMF and MAPA (Slope = 1.009, Pearson's correlation coefficient R = 0.982) and a good correlation for the case of HCHO (R = 0.927). For aerosols, we find better agreement for the aerosol optical depths (AODs) in the visible (i.e., at 477 nm), compared to the UV (360 nm) and we show that the agreement strongly depends on the O4 scaling factor that is used in the analysis. The trace gas differential slant column densities (dSCDs), simulated by the forward models, are also in good agreement, except for HCHO, where larger scatter is observed due to the increased spectral noise of the measurements in the UV. The agreement for NO2 and HCHO surface concentrations is similar to the comparison of the integrated columns with slightly decreased correlation coefficients. The AODs retrieved by the MAX-DOAS are validated by comparing them with AOD values measured by a CIMEL sun-photometer and a Brewer spectrophotometer. Four different flagging schemes were applied to the data in order to evaluate their performance. Qualitatively, a generally good agreement is observed for both wavelengths, but we find a systematic bias from the CIMEL and Brewer measurements, due to the limited sensitivity of the MAX-DOAS in retrieving information at higher altitudes, especially in the UV. An in-depth validation of the aerosol vertical profiles retrieved by the MAX-DOAS is not possible since only in very few cases the true aerosol profile is known during the period of study. However, we examine four cases, where the MAX-DOAS provided a generally good estimation of the shape of the profiles retrieved by a co-located multi-wavelength lidar system. The NO2 surface concentrations are validated against in situ observations and the comparison of both MMF and MAPA revealed good agreement with correlation coefficients of R = 0.78 and R = 0.73, respectively. Finally, the effect of the O4 scaling factor is investigated by intercomparing the integrated columns retrieved by the two algorithms and also by comparing the AODs derived by MAPA for different values of the scaling factor with AODs measured by the CIMEL and the Brewer.
... Other studies, however, did not find the need to apply such a scaling factor (e.g. Spinei et al., 2015;Ortega et al., 2016). A more detailed discussion and overview of existing studies of both groups are provided in Wagner et al. (2019). ...
... The details of the analysis are given in Table 1. Figure A1 (left) presents an example of the spectral analysis as used in this study. In addition to the other cross sections, also an H 2 O cross section (Polyansky et al., 2018) is included. The reason for including an H 2 O cross section as well as the effect of including a second O 4 cross section are discussed in Appendix A1. ...
... If the H 2 O cross section is not included in the analysis, a systematic structure appears in the residual. Thus, in this study, a water vapour cross section (Polyansky et al., 2018) is included in the spectral analysis. Here, it should be noted that compared to other locations, the water vapour absorption during the ship cruise was rather high because most of the measurements were carried out under conditions of high atmospheric temperature and humidity. ...
In this study, we compare measured and simulated O4 absorptions for conditions of extremely low aerosol optical depth (between 0.034 to 0.056 at 360 nm) on one day during a ship cruise in the tropical Atlantic. For such conditions, the uncertainties related to imperfect knowledge of aerosol properties do not significantly affect the comparison results. We find that the simulations underestimate the measurements by 15 % to 20 %. Even for simulations without any aerosols, the measured O4 absorptions are still systematically higher than the simulation results. The observed discrepancies cannot be explained by uncertainties of the measurements and simulations and thus indicate a fundamental inconsistency between simulations and measurements.
... Several previous studies have shown that there is a systematic discrepancy between observation and model simulation of O 4 DSCDs Wagner et al., 2011;Clémer et al., 2010;Chan et al., 2015;Wang et al., 2016;Chan et al., 2018;Zhang et al., 2018). However, other studies found that the modeled and measured O 4 DSCDs match with each other without applying any correction (Spinei et al., 2015;Ortega et al., 2016;Wagner et al., 2019). The discrepancies can be related to the systematic error of the O 4 absorption cross section, model error, optical properties of aerosols and aerosols above the retrieval height (Ortega et al., 2016;Wagner et al., 2019). ...
We present two-dimensional scanning Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations of nitrogen dioxide (NO2) and formaldehyde (HCHO) in Munich. Vertical columns and vertical distribution profiles of aerosol extinction coefficient, NO2 and HCHO are retrieved from the 2D MAX-DOAS observations. The measured surface aerosol extinction coefficients and NO2 mixing ratios derived from the retrieved profiles are compared to in situ monitoring data, and the surface NO2 mixing ratios show a good agreement with in situ monitoring data with a Pearson correlation coefficient (R) of 0.91. The aerosol optical depths (AODs) show good agreement as well (R=0.80) when compared to sun photometer measurements. Tropospheric vertical column densities (VCDs) of NO2 and HCHO derived from the MAX-DOAS measurements are also used to validate Ozone Monitoring Instrument (OMI) and TROPOspheric Monitoring Instrument (TROPOMI) satellite observations. Monthly averaged data show a good correlation; however, satellite observations are on average 30 % lower than the MAX-DOAS measurements. Furthermore, the MAX-DOAS observations are used to investigate the spatiotemporal characteristic of NO2 and HCHO in Munich. Analysis of the relations between aerosol, NO2 and HCHO shows higher aerosol-to-HCHO ratios in winter, which reflects a longer atmospheric lifetime of secondary aerosol and HCHO during winter. The analysis also suggests that secondary aerosol formation is the major source of these aerosols in Munich.
... In this spectral band, O 2 -O 2 dimer (O 4 ) has a single strong line at 477 nm. Content of O 4 is very stable within the atmosphere, and so O 4 is commonly used as a tracer to retrieve optical thickness of aerosols [15,16]. Based on the above considerations, we designed and fabricated a 2-D broadband monolithic SHS interferometer which comprises a cube beam splitter, two diffraction gratings, two prisms and four spacers. ...
A broadband monolithic spatial heterodyne spectrometer (SHS) system is built for measuring nitrogen dioxide in the atmosphere based on our newly developed fabrication technique. This system is calibrated and tested with Hg, Kr and Xe lamps, as well as monochromator output illuminated by a high-voltage Xe lamp (as a white light source). The obtained overall efficiency profile presents an effective spectral range of 425-495 nm (when the efficiency values are greater than 40%). The maximum fringe visibility is ~0.85. The measured instrumental line shape function gives an actual spectral resolution of ~0.073 nm. The effect of phase distortion of this 2-D SHS system can be neglected. Direct solar-irradiance spectra in the NO2 absorption band were measured with the SHS system. The measured spectra are consistent with the results simulated by Modtran6 within the SHS spectral range. The vertical column contents of NO2, VC(NO2), derived from the SHS data by the direct sun - differential optical absorption spectroscopy (DS-DOAS) method coincide closely with the simultaneously acquired (OMI) satellite data.
