<title>Monocyclic aromatic hydrocarbons measured by differential optical absorption spectroscopy in urban areas (China)</title>

Abstract. Trace gases play a key role in the chemistry of urban atmospheres. Therefore, knowledge about their spatial distribution is needed to fully characterize air quality in urban areas. Using a new Multi-AXis Differential Optical Absorption Spectroscopy two-dimensional (MAXDOAS-2D) instrument, along with an inversion algorithm (bePRO), we report the first two-dimensional maps of nitrogen dioxide (NO2) and nitrous acid (HONO) concentrations in the city of Madrid, Spain. Measurements were made during 2 months (6 May–5 July 2019), and peak mixing ratios of 12 and 0.7 ppbv (parts per billion by volume) for NO2 and HONO, respectively, were observed in the early morning in the southern part of the downtown area. We found good general agreement between the MAXDOAS-2D mesoscale observations – which provide a typical spatial range of a few kilometers – and the in situ measurements provided by Madrid's air quality monitoring stations. In addition to vertical profiles, we studied the horizontal gradients of NO2 in the surface layer by applying the different horizontal light path lengths in the two spectral regions included in the NO2 spectral analysis: ultraviolet (UV, at 360 nm) and visible (VIS, 477 nm). We also investigate the sensitivity of the instrument to infer vertically distributed information on aerosol extinction coefficients and discuss possible future ways to improve the retrievals. The retrieval of two-dimensional distributions of trace gas concentrations reported here provides valuable spatial information for the study of air quality in the city of Madrid.

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Estimating real driving emissions from multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements at the A60 motorway near Mainz, Germany

Atmospheric Measurement Techniques ◽

10.5194/amt-14-769-2021 ◽

2021 ◽

Vol 14 (1) ◽

pp. 769-783

Author(s):

Bianca Lauster ◽

Steffen Dörner ◽

Steffen Beirle ◽

Sebastian Donner ◽

Sergey Gromov ◽

...

Keyword(s):

Nitrogen Oxides ◽

Optical Absorption ◽

Absorption Spectroscopy ◽

Urban Areas ◽

Road Traffic ◽

Differential Optical Absorption Spectroscopy ◽

Optical Absorption Spectroscopy ◽

Nox Emissions ◽

Emission Standards

Abstract. In urban areas, road traffic is a dominant source of nitrogen oxides (NOx=NO+NO2). Although the emissions from individual vehicles are regulated by the European emission standards, real driving emissions often exceed these limits. In this study, two multi-axis differential optical absorption spectroscopy (MAX-DOAS) instruments on opposite sides of the motorway were used to measure the NO2 absorption caused by road traffic at the A60 motorway close to Mainz, Germany. In combination with wind data, the total NOx emissions for the occurring traffic volume can be estimated. Hereto, the ozone-dependent photochemical equilibrium between NO and NO2 is considered. We show that for 10 May 2019 the measured emissions exceed the maximum expected emissions calculated from the European emission standards for standardised test cycles by a factor of 11±7. One major advantage of the method used here is that MAX-DOAS measurements are very sensitive to the integrated NO2 concentration close to the surface. Thus, all emitted NO2 molecules are detected independently from their altitude, and therefore the whole emission plume originating from the nearby motorway is captured, which is a key advantage compared to other approaches such as in situ measurements.

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Recent applications of Differential Optical Absorption Spectroscopy: Halogen chemistry in the lower troposphere

Journal de Physique IV (Proceedings) ◽

10.1051/jp4:2004121015 ◽

2004 ◽

Vol 121 ◽

pp. 223-238 ◽

Cited By ~ 4

Author(s):

A. Saiz-Lopez ◽

J. M.C. Plane

Keyword(s):

Optical Absorption ◽

Absorption Spectroscopy ◽

Lower Troposphere ◽

Differential Optical Absorption Spectroscopy ◽

Optical Absorption Spectroscopy ◽

Halogen Chemistry

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Total Ozone Columns from the Environmental Trace Gases Monitoring Instrument (EMI) Using the DOAS Method

Remote Sensing ◽

10.3390/rs13112098 ◽

2021 ◽

Vol 13 (11) ◽

pp. 2098

Author(s):

Yuanyuan Qian ◽

Yuhan Luo ◽

Fuqi Si ◽

Haijin Zhou ◽

Taiping Yang ◽

...

Keyword(s):

Optical Absorption ◽

Absorption Spectroscopy ◽

Total Ozone ◽

Scattered Light ◽

Trace Gases ◽

Rapid Change ◽

Differential Optical Absorption Spectroscopy ◽

Optical Absorption Spectroscopy ◽

Monitoring Instrument ◽

Monthly Average

Global measurements of total ozone are necessary to evaluate ozone hole recovery above Antarctica. The Environmental Trace Gases Monitoring Instrument (EMI) onboard GaoFen 5, launched in May 2018, was developed to measure and monitor the global total ozone column (TOC) and distributions of other trace gases. In this study, some of the first global TOC results of the EMI using the differential optical absorption spectroscopy (DOAS) method and validation with ground-based TOC measurements and data derived from Ozone Monitoring Instrument (OMI) and TROPOspheric Monitoring Instrument (TROPOMI) observations are presented. Results show that monthly average EMI TOC data had a similar spatial distribution and a high correlation coefficient (R ≥ 0.99) with both OMI and TROPOMI TOC. Comparisons with ground-based measurements from the World Ozone and Ultraviolet Radiation Data Centre also revealed strong correlations (R > 0.9). Continuous zenith sky measurements from zenith scattered light differential optical absorption spectroscopy instruments in Antarctica were also used for validation (R = 0.9). The EMI-derived observations were able to account for the rapid change in TOC associated with the sudden stratospheric warming event in October 2019; monthly average TOC in October 2019 was 45% higher compared to October 2018. These results indicate that EMI TOC derived using the DOAS method is reliable and has the potential to be used for global TOC monitoring.

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Satellite monitoring of different vegetation types by differential optical absorption spectroscopy (DOAS) in the red spectral range

Atmospheric Chemistry and Physics ◽

10.5194/acp-7-69-2007 ◽

2007 ◽

Vol 7 (1) ◽

pp. 69-79 ◽

Cited By ~ 20

Author(s):

T. Wagner ◽

S. Beirle ◽

T. Deutschmann ◽

M. Grzegorski ◽

U. Platt

Keyword(s):

Optical Absorption ◽

Absorption Spectroscopy ◽

Spectral Range ◽

Near Infrared ◽

Vegetation Type ◽

Differential Optical Absorption Spectroscopy ◽

Trace Gas ◽

Satellite Monitoring ◽

Optical Absorption Spectroscopy ◽

Vegetation Types

Abstract. A new method for the satellite remote sensing of different types of vegetation and ocean colour is presented. In contrast to existing algorithms relying on the strong change of the reflectivity in the red and near infrared spectral region, our method analyses weak narrow-band (few nm) reflectance structures (i.e. "fingerprint" structures) of vegetation in the red spectral range. It is based on differential optical absorption spectroscopy (DOAS), which is usually applied for the analysis of atmospheric trace gas absorptions. Since the spectra of atmospheric absorption and vegetation reflectance are simultaneously included in the analysis, the effects of atmospheric absorptions are automatically corrected (in contrast to other algorithms). The inclusion of the vegetation spectra also significantly improves the results of the trace gas retrieval. The global maps of the results illustrate the seasonal cycles of different vegetation types. In addition to the vegetation distribution on land, they also show patterns of biological activity in the oceans. Our results indicate that improved sets of vegetation spectra might lead to more accurate and more specific identification of vegetation type in the future.

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