scholarly journals Retrieval interval mapping: a tool to visualize the impact of the spectral retrieval range on differential optical absorption spectroscopy evaluations

2013 ◽  
Vol 6 (2) ◽  
pp. 275-299 ◽  
Author(s):  
L. Vogel ◽  
H. Sihler ◽  
J. Lampel ◽  
T. Wagner ◽  
U. Platt
Keyword(s):  
Optical Absorption ◽  
Wavelength Range ◽  
Absorption Spectroscopy ◽  
Trace Gases ◽  
Differential Optical Absorption Spectroscopy ◽  
General Nature ◽  
Optical Absorption Spectroscopy ◽  
Wide Range ◽  
The Impact ◽  
Optimal Retrieval

Abstract. Remote sensing via differential optical absorption spectroscopy (DOAS) has become a standard technique to identify and quantify trace gases in the atmosphere. Due to the wide range of measurement conditions, atmospheric compositions and instruments used, a specific challenge of a DOAS retrieval is to optimize the retrieval parameters for each specific case and particular trace gas of interest. Of these parameters, the retrieval wavelength range is one of the most important ones. Although for many trace gases the overall dependence of common DOAS retrieval on the evaluation wavelength interval is known, a systematic approach for finding the optimal retrieval wavelength range and quantitative assessment is missing. Here we present a novel tool to visualize the effect of different evaluation wavelength ranges. It is based on mapping retrieved column densities in the retrieval wavelength space and thus visualizing the consequences of different choices of spectral retrieval ranges caused by slightly erroneous absorption cross sections, cross correlations and instrumental features. Based on the information gathered, an optimal retrieval wavelength range may be determined systematically. The technique is demonstrated using examples of a theoretical study of BrO retrievals for stratospheric BrO and BrO measurements in volcanic plumes. However, due to the general nature of the tool, it is applicable to any type of DOAS retrieval (active or passive).

scholarly journals Retrieval interval mapping, a tool to optimize the spectral retrieval range in differential optical absorption spectroscopy

2012 ◽  
Vol 5 (3) ◽  
pp. 4195-4247 ◽  
Author(s):  
L. Vogel ◽  
H. Sihler ◽  
J. Lampel ◽  
T. Wagner ◽  
U. Platt
Keyword(s):  
Optical Absorption ◽  
Wavelength Range ◽  
Absorption Spectroscopy ◽  
Cross Sections ◽  
Trace Gases ◽  
Differential Optical Absorption Spectroscopy ◽  
Trace Gas ◽  
General Nature ◽  
Optical Absorption Spectroscopy ◽  
Cross Correlations

Abstract. Remote sensing via differential optical absorption spectroscopy (DOAS) has become a standard technique to identify and quantify trace gases in the atmosphere. The technique is applied in a variety of configurations, commonly classified into active and passive instruments using artificial and natural light sources, respectively. Platforms range from ground based to satellite instruments and trace-gases are studied in all kinds of different environments. Due to the wide range of measurement conditions, atmospheric compositions and instruments used, a specific challenge of a DOAS retrieval is to optimize the parameters for each specific case and particular trace gas of interest. This becomes especially important when measuring close to the detection limit. A well chosen evaluation wavelength range is crucial to the DOAS technique. It should encompass strong absorption bands of the trace gas of interest in order to maximize the sensitivity of the retrieval, while at the same time minimizing absorption structures of other trace gases and thus potential interferences. Also, instrumental limitations and wavelength depending sources of errors (e.g. insufficient corrections for the Ring effect and cross correlations between trace gas cross sections) need to be taken into account. Most often, not all of these requirements can be fulfilled simultaneously and a compromise needs to be found depending on the conditions at hand. Although for many trace gases the overall dependence of common DOAS retrieval on the evaluation wavelength interval is known, a systematic approach to find the optimal retrieval wavelength range and qualitative assessment is missing. Here we present a novel tool to determine the optimal evaluation wavelength range. It is based on mapping retrieved values in the retrieval wavelength space and thus visualize the consequence of different choices of retrieval spectral ranges, e.g. caused by slightly erroneous absorption cross sections, cross correlations and instrumental features. The technique is demonstrated using the examples of a theoretical study of BrO retrievals for stratospheric BrO measurements and for BrO measurements in volcanic plumes. However, due to the general nature of the tool, it is applicable to any type (active or passive) of DOAS retrieval.

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

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.

Effect of Spectral Resolution on Measurement of Trace Gases in Atmosphere by Differential Optical Absorption Spectroscopy

2008 ◽  
Vol 28 (9) ◽  
pp. 1643-1648
Author(s):  
彭夫敏 彭夫敏 ◽  
谢品华 谢品华 ◽  
张英华 张英华 ◽  
李海洋 李海洋 ◽  
司福祺 司福祺 ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Absorption Spectroscopy ◽  
Spectral Resolution ◽  
Trace Gases ◽  
Differential Optical Absorption Spectroscopy ◽  
Optical Absorption Spectroscopy

scholarly journals Ground-based measurements of atmospheric trace gases using differential optical absorption spectroscopy and comparisons with satellite observations

2021 ◽  
Author(s):  
Θεανώ Δρόσογλου
Keyword(s):  
Optical Absorption ◽  
Absorption Spectroscopy ◽  
Trace Gases ◽  
Satellite Observations ◽  
Differential Optical Absorption Spectroscopy ◽  
Optical Absorption Spectroscopy ◽  
Atmospheric Trace Gases

Κύριο αντικείμενο αυτής της διατριβής είναι ο υπολογισμός της κατακόρυφης στήλης ατμοσφαιρικών αερίων με εστίαση στο διοξείδιο του αζώτου (ΝΟ2) χρησιμοποιώντας την τεχνική της φασματοσκοπίας διαφορικής οπτικής απορρόφησης (DOAS) και συγκρίσεις με δορυφορικά δεδομένα. Η διατριβή αποτελείται από δύο κύρια μέρη. Το πρώτο μέρος περιλαμβάνει την τεχνική περιγραφή και τον χαρακτηρισμό των τριών συστημάτων Multi-Axis DOAS που αναπτύχθηκαν στο Εργαστήριο Φυσικής της Ατμόσφαιρας (ΕΦΑ) στη Θεσσαλονίκη, καθώς και μια αξιολόγηση της λειτουργίας και της ποιότητας των μετρήσεων του συστήματος στο πλαίσιο της εκστρατείας CINDI-2 που πραγματοποιήθηκε στο Cabauw της Ολλανδίας τον Σεπτέμβριο του 2016. Στο δεύτερο μέρος, παρουσιάζονται μετρήσεις της τροποσφαιρικής και στρατοσφαιρικής στήλης NO2, καθώς και συγκρίσεις τους δορυφορικές παρατηρήσεις. Πιο συγκεκριμένα, εξετάζεται η επίδραση της χωρικής μεταβλητότητας του ΝΟ2 κοντά στην επιφάνεια στις συγκρίσεις επίγειων και δορυφορικών μετρήσεων. Στο πλαίσιο αυτό, τα τρία όργανα MAX-DOAS του ΕΦΑ εγκαταστάθηκαν σε διαφορετικές τοποθεσίες στην ευρύτερη περιοχή της Θεσσαλονίκης που χαρακτηρίζονται από διαφορετικά επίπεδα ρύπανσης και υπολογίστηκαν συντελεστές διόρθωσης με τη βοήθεια ενός μοντέλου ποιότητας αέρα, οι οποίοι εφαρμόστηκαν σε δορυφορικά δεδομένα προκειμένου να προσαρμοστούν στη χωρική ανάλυση των επίγειων μετρήσεων. Επιπλέον, παρουσιάζονται τα αποτελέσματα των μετρήσεων της τροποσφαιρικής στήλης του ΝΟ2 στη ρυπασμένη περιοχή της Guangzhou της Κίνας και συγκρίνονται με αντίστοιχες δορυφορικές μετρήσεις. Διερευνήθηκε επίσης η επίδραση των κριτηρίων αντιστοίχισης των επίγειων και των δορυφορικών τροσφαιρικών στηλών του NO2. Τέλος, υπολογίστηκαν οι συγκεντρώσεις του στρατοσφαιρικού NO2 για πρώτη φορά στη Θεσσαλονίκη από την ανάλυση DOAS των φασματικών μετρήσεων ακτινοβολίας που πραγματοποιήθηκαν στο ζενίθ κατά το λυκόφως για μια περίοδο 7 ετών (Απρίλιος 2011 - Απρίλιος 2018).

scholarly journals Tropospheric NO<sub>2</sub>, SO<sub>2</sub>, and HCHO over the East China Sea, using ship-based MAX-DOAS observations and comparison with OMI and OMPS satellites data

2018 ◽  
Author(s):  
Wei Tan ◽  
Cheng Liu ◽  
Shanshan Wang ◽  
Chengzhi Xing ◽  
Wenjing Su ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Correlation Coefficient ◽  
Absorption Spectroscopy ◽  
Trace Gases ◽  
Eastern China ◽  
Elevation Angle ◽  
Estimation Method ◽  
Differential Optical Absorption Spectroscopy ◽  
Optical Absorption Spectroscopy ◽  
China Sea

Abstract. In this study, ship-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements were performed in the Eastern China Sea (ECS) area in June 2017. The tropospheric Slant Column Densities (SCDs) of nitrogen dioxide (NO2), sulfur dioxide (SO2), and formaldehyde (HCHO) were retrieved from the measured spectra by the Differential Optical Absorption Spectroscopy (DOAS) technique. Using the simple geometric approach, the SCDs of different trace gases observed at 15° elevation angle were adopted to convert into tropospheric Vertical Columns Densities (VCDs). During this campaign, the averaged VCDs of NO2, SO2, and HCHO in the marine environment over ECS area are 6.50 &amp;times 1015 molec cm−2, 4.28 &amp;times 1015 molec cm−2 and 7.39 &amp;times 1015 molec cm−2, respectively. In addition, the ship-based MAX-DOAS trace gases VCDs were compared with satellite observations of Ozone Monitoring Instrument (OMI) and Ozone Mapping and Profiler Suite (OMPS). The daily OMI NO2 VCDs agree well with ship-based MAX-DOAS measurements showing the correlation coefficient R of 0.83. Besides, the good agreements of SO2 and HCHO VCDs between the OMPS satellite and ship-based MAX-DOAS observations were also found with correlation coefficient R of 0.76 and 0.69. The vertical profiles of these trace gases are achieved from the measured Differential Slant Column Densities (DSCDs) at different elevation angles using optimal estimation method. The retrieved profiles displayed the typical vertical distribution characteristics, which exhibits the low concentrations of

scholarly journals Measurements of O3</sub>, NO<sub>2</sub> and BrO at the Kaashidhoo Climate Observatory (KCO) during the INDOEX (INDian Ocean EXperiment) Campaign using ground based DOAS (Differential Optical Absorption Spectroscopy) and satellite based GOME (Global Ozone Monitoring Experiment) data

2006 ◽  
Vol 6 (5) ◽  
pp. 9273-9296
Author(s):  
A. Ladstätter-Weißenmayer ◽  
H. Altmeyer ◽  
M. Bruns ◽  
A. Richter ◽  
A. Rozanov ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Optical Absorption ◽  
Absorption Spectroscopy ◽  
Single Case ◽  
Differential Optical Absorption Spectroscopy ◽  
Optical Absorption Spectroscopy ◽  
Experiment Data ◽  
The Indian Ocean ◽  
The Impact

Abstract. The INDian Ocean EXperiment (INDOEX) was an international, multi-platform field campaign to measure long-range transport of air masses from South and South-East-(SE) Asia towards the Indian Ocean. During the dry monsoon season between January and March 1999, local measurements were carried out from ground based platforms and were compared with satellite based data. The objective of this study was to characterise stratospheric and tropospheric trace gas amounts in the equatorial region, and to investigate the impact of air pollution at this remote site. For the characterisation of the chemical composition of the outflow from the S-SE-Asian region, we performed ground based dual-axis-DOAS (Differential Optical Absorption Spectroscopy) measurements at the KCO (Kaashidhoo Climate Observatory) in the Maldives (5.0° N, 73.5° E). The ground based dual-axis-DOAS measurements were conducted using two different observation modes (off-axis and zenith-sky). This technique allows the separation of the tropospheric and stratospheric columns for different trace gases like O3 and NO2. These dual-axis DOAS data were compared with O3-sonde measurements performed at KCO and satellite based GOME (Global Ozone Measuring Experiment) data during the intensive measuring phase of the INDOEX campaign in February and March 1999. From GOME observations, tropospheric and stratospheric columns for O3 and NO2 were retrieved. In addition, the analysis of the O3-sonde measurements allowed the determination of the tropospheric O3 amount. The comparison shows that the results of all three measurement systems agree within their error limits. During the INDOEX campaign, background conditions were observed most of the time, but in a single case an increase of tropospheric NO2 during a short pollution event was observed and the impact on the vertical columns was calculated. In the GOME measurements, evidence was found for large tropospheric contributions to the BrO budget, probably located in the free troposphere and present throughout the year. The latter has been investigated by the comparison of satellite pixels influenced by high and low cloud conditions based on GOME data which allows the determination of the detection limit of tropospheric BrO columns.

scholarly journals A rapid method to derive horizontal distributions of trace gases and aerosols near the surface using multi-axis differential optical absorption spectroscopy

2013 ◽  
Vol 6 (5) ◽  
pp. 8129-8186
Author(s):  
Y. Wang ◽  
A. Li ◽  
P. H. Xie ◽  
T. Wagner ◽  
H. Chen ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Rapid Method ◽  
Absorption Spectroscopy ◽  
Trace Gases ◽  
Elevation Angle ◽  
Differential Optical Absorption Spectroscopy ◽  
Optical Absorption Spectroscopy ◽  
Aerosol Extinction ◽  
Correction Factors ◽  
Light Path

Abstract. We apply a novel experimental procedure for the rapid measurement of the average volume mixing ratios (VMRs) and horizontal distributions of trace gases such as NO2, SO2, and HCHO in the boundary layer, which was recently suggested by Sinreich et al. (2013). The method is based on two-dimensional scanning multi-axis differential optical absorption spectroscopy (MAX-DOAS). It makes use of two facts (Sinreich et al. 2013): First, the light path for observations at 1° elevation angle traverses mainly air masses located close to the ground (typically < 200 m). Second, the light path length can be calculated using the simultaneous measured absorption of the oxygen dimer O4. Thus, the average value of the trace gas VMR in the atmospheric layer between the surface and the altitude, for which this observation was sensitive, can be calculated. Compared to the originally proposed method, we introduce several important modifications and improvements: We apply the method only to measurements at 1° elevation angles, for which the uncertainties are especially small. Using only 1 elevation angle also allows an increased temporal resolution. We apply correction factors (and their uncertainties) as function of the simultaneously modelled O4 absorption. In this way the correction factors can be directly determined according to the measured O4 dAMF. Finally, the method is extended to trace gases analysed at other wavelengths and also to the retrieval of the aerosol extinction. Depending on the atmospheric visibility, the typical uncertainty of the results ranges from about 15 to 30%. We apply the rapid method to observations of a newly developed ground-based multifunctional passive differential optical absorption spectroscopy (GM-DOAS) instrument in the north-west outskirt near Hefei City in China. We report NO2, SO2, and HCHO VMRs and aerosol extinction for four azimuth angles and compare these results with those from simultaneous long-path DOAS observations. Good agreement is found (squares of the correlation coefficients for NO2, SO2, and HCHO were 0.92, 0.84, and 0.59, respectively), verifying the reliability of this novel method. Similar agreement is found for the comparison of the aerosol extinction with results from visibility meters. Future studies may conduct measurements using a larger number of azimuth angles to increase the spatial resolution.

scholarly journals A rapid method to derive horizontal distributions of trace gases and aerosols near the surface using multi-axis differential optical absorption spectroscopy

2014 ◽  
Vol 7 (6) ◽  
pp. 1663-1680 ◽  
Author(s):  
Y. Wang ◽  
A. Li ◽  
P. H. Xie ◽  
T. Wagner ◽  
H. Chen ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Rapid Method ◽  
Absorption Spectroscopy ◽  
Trace Gases ◽  
Elevation Angle ◽  
Differential Optical Absorption Spectroscopy ◽  
Optical Absorption Spectroscopy ◽  
Aerosol Extinction ◽  
Light Path ◽  
North West

Abstract. We apply a novel experimental procedure for the rapid measurement of the average volume mixing ratios (VMRs) and horizontal distributions of trace gases such as NO2, SO2, and HCHO in the boundary layer, which was recently suggested by Sinreich et al. (2013). The method is based on two-dimensional scanning multi-axis differential optical absorption spectroscopy (MAX-DOAS). It makes use of two facts (Sinreich et al., 2013): first, the light path for observations at 1° elevation angle traverses mainly air masses located close to the ground (typically < 200 m); second, the light path length can be calculated using the simultaneous measured absorption of the oxygen dimer O4. Thus, the average value of the trace gas VMR in the atmospheric layer between the surface and the particular altitude, for which this observation was sensitive, can be calculated. Compared to the originally proposed method, we introduce several important modifications and improvements: We apply the method only to measurements at 1° elevation angle (besides zenith view), for which the uncertainties of the retrieved values of the VMRs and surface extinctions are especially small. Using only 1° elevation angle for off-axis observation also allows an increased temporal resolution. We determine (and apply) correction factors (and their uncertainties) directly as function of the measured O4 absorption. Finally, the method is extended to trace gases analysed at other wavelengths and also to the retrieval of aerosol extinction. Depending on atmospheric visibility, the typical uncertainty of the results ranges from about 20% to 30%. We apply the rapid method to observations of a newly-developed ground-based multifunctional passive differential optical absorption spectroscopy (GM-DOAS) instrument in the north-west outskirts near Hefei in China. We report NO2, SO2, and HCHO VMRs and aerosol extinction for four azimuth angles and compare these results with those from simultaneous long-path DOAS observations. Good agreement is found (squares of the correlation coefficients for NO2, SO2, and HCHO were 0.92, 0.85, and 0.60, respectively), verifying the reliability of this novel method. Similar agreement is found for the comparison of the aerosol extinction with results from visibility meters. Future studies may conduct measurements using a larger number of azimuth angles to increase the spatial resolution.

scholarly journals Tropospheric NO<sub>2</sub>, SO<sub>2</sub>, and HCHO over the East China Sea, using ship-based MAX-DOAS observations and comparison with OMI and OMPS satellite data

2018 ◽  
Vol 18 (20) ◽  
pp. 15387-15402 ◽  
Author(s):  
Wei Tan ◽  
Cheng Liu ◽  
Shanshan Wang ◽  
Chengzhi Xing ◽  
Wenjing Su ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Optical Absorption ◽  
East China Sea ◽  
Absorption Spectroscopy ◽  
Marine Boundary Layer ◽  
Trace Gases ◽  
Differential Optical Absorption Spectroscopy ◽  
East China ◽  
Optical Absorption Spectroscopy ◽  
The East China Sea

Abstract. In this study, ship-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements were performed in the East China Sea (ECS) area in June 2017. The tropospheric slant column densities (SCDs) of nitrogen dioxide (NO2), sulfur dioxide (SO2), and formaldehyde (HCHO) were retrieved from the measured spectra using the differential optical absorption spectroscopy (DOAS) technique. Using the simple geometric approach, the SCDs of different trace gases observed at a 15∘ elevation angle were adopted to convert into tropospheric vertical column densities (VCDs). During this campaign, the averaged VCDs of NO2, SO2, and HCHO in the marine environment over the ECS area are 6.50×1015, 4.28×1015, and 7.39×1015 molec cm−2, respectively. In addition, the ship-based MAX-DOAS trace gas VCDs were compared with satellite observations of the Ozone Monitoring Instrument (OMI) and Ozone Mapping and Profiler Suite (OMPS). The daily OMI NO2 VCDs agreed well with ship-based MAX-DOAS measurements showing the correlation coefficient R of 0.83. In addition, the good agreements of SO2 and HCHO VCDs between the OMPS satellite and ship-based MAX-DOAS observations were also found, with correlation coefficients R of 0.76 and 0.69. The vertical profiles of these trace gases are achieved from the measured differential slant column densities (DSCDs) at different elevation angles using the optimal estimation method. The retrieved profiles displayed the typical vertical distribution characteristics, which exhibit low concentrations of <3, <3, and <2 ppbv for NO2, SO2, and HCHO in a clean area of the marine boundary layer far from coast of the Yangtze River Delta (YRD) continental region. Interestingly, elevated SO2 concentrations can be observed intermittently along the ship routes, which is mainly attributed to the vicinal ship emissions in the view of the MAX-DOAS measurements. Combined with the on-board ozone lidar measurements, the ozone (O3) formation was discussed with the vertical profile of the HCHO∕NO2 ratio, which is sensitive to increases in NO2 concentration. This study provided further understanding of the main air pollutants in the marine boundary layer of the ECS area and also benefited the formulation of policies regulating the shipping emissions in such costal areas like the YRD region.

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