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MAX-DOAS observations in YRD and comparisons with satellite data

This study presents the progress and results of MAX-DOAS observations in the Yangzi River Delta, including validation of satellite products and comparisons with model data. The validation activities include measurements of NOx, VOC, SO2, glyoxal, aerosols, and AOD data using MAX-DOAS and mobile DOAS.

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MAX-DOAS observations in YRD and comparisons with satellite data

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  1. MAX-DOAS observations in YRD and comparisons with satellite data PinhuaXie1, Jin Xu1, Ang Li1, Yang Wang1,2, Xin Tian1 1) Hefei Institutes of Physical Science, CAS 2) Satellite group, MPIC March 1th, 2017

  2. Outline • Introduction instruments and Progress. • Progress in Wuxi, Shanghai and Hefei stations • The data of MAX-DOAS • Validation of the satellite products • Comparisons with model data • Conclusion

  3. T6.4 - Validation using MAX-DOAS measurements [Months: 12-36] HIPS, IASB - BIRA • Validation of NOx, VOC, SO2, glyoxal, aerosols from satellite and models using observations from MAX-DOAS and mobile DOAS on several locations in the region of the Yangzi River Delta • Validation of NO2 and HCHO using MAX-DOAS measurements obtained at Beijing and Xianghe. T6.5 - Validation of aerosols [Months: 6-36] FMI, IAP,HIPS • Validation using the aerosol measurements at a ground station NW of Beijing (FMI) • Validation using the Aeronet-like network of ground stations over China. (IAP) • Validation of AOD data using sunphotometer measurements in Hefei.(HIPS)

  4. Introduction of MAX-DOAS stations Shanghai Wuxi Hefei 2D MAX-DOAS mini MAX-DOAS • spectrometer: Princeton Instrument Acton SP500i Imaging Czerny–Turner spectrometer with spectral resolution of 0.35 nm over a spectral range from 290 – 385 nm (NO2, SO2, HCHO and O4). • Elevation angle: 1°, 2°, 3°, 4°, 5°, 6°, 8°, 10°, 15°, 30°, 90° Azimuth angle: North, east, south and west • spectrometer: a crossed Czerny-Turner spectrometer (HR2000+, Ocean Optics Inc.) spectral resolution of 0.5 nm over a spectral range from 290 – 425 nm (NO2, SO2, HCHO and O4). • Elevation angle: 5°, 10°, 20°, 30° and 90° • Azimuth angle: Exact north

  5. The Progresses of HIPS The detailed information on the three stations

  6. dSCD retrieval: Parameters of DOAS fit for NO2 and O4

  7. dSCD retrieval: DOAS fit for NO2, O4, SO2 and HCHO The typical DOAS fits of NO2, O4, SO2 and HCHO.

  8. Information on the involved satellite products in the validation activities

  9. 1. Evaluation of MAX-DOAS and filter scheme Comparisons of AODs, near-surface AEs, NO2 and SO2 VMRs between MAX-DOAS and independent techniques for different seasons for clear sky conditions with low aerosols.

  10. 1. Evaluation of MAX-DOAS and filter scheme Comparisons of AODs, near-surface AEs, NO2 and SO2 VMRs between MAX-DOAS and independent techniques for different seasons for different sky conditions.

  11. 1. Evaluation of MAX-DOAS and filter scheme Mean profiles of aerosol extinctions (a), NO2 VMRs (c), SO2 VMRs (e) and HCHO VMRs (g) from all MAX-DOAS observations under individual sky conditions

  12. 2. Validation of the satellite products——Wuxi station • NO2 VCD: The R2, slopes and intercepts of the linear regressions, the MRD as well as the number of available days for the three satellite products with MAX-DOAS for six eCF bins from 2011 to 2014. OMI: R2 decrease with increasing eCF GOME-2A: a steep decrease of R2 for eCF > 30% GOME-2B: a generally lower R2 in eCF >30%

  13. 2. Validation of the satellite products——Wuxi station • Comparisons of daily averaged NO2 VCD between MAX-DOAS and three satellite for eCF<10% in Wuxi from 2011 to 2014 Higher correlation coefficients R2 for OMI than for GOME-2A/B

  14. 2. Validation of the satellite products——Wuxi station • SO2 VCD: The R2, slopes and intercepts of the linear regressions, the MRD as well as the number of available days for the three satellite products with MAX-DOAS for six eCF bins from 2011 to 2014. OMI BIRA : a significant decrease of R2 occurs for eCF > 10% together with a decrease of the slopes and the MRD. OMI NASA: R2, slope and MRD significantly decrease for eCF > 20% GOME-2A: most accurate for eCF < 30%. GOME-2B BIRA: eCFs of <10% are ecommend to use.

  15. 2. Validation of the satellite products——Wuxi station • Comparisons of daily averaged SO2 VCD between MAX-DOAS and three satellite for eCF<10% in Wuxi from 2011 to 2014

  16. 2. Validation of the satellite products——Wuxi station • HCHO VCD: The R2, slopes and intercepts of the linear regressions, the MRD as well as the number of available days for the three satellite products with MAX-DOAS for four eCF bins from 2011 to 2014. OMI: a decrease of R2 occurs for eCF > 30% GOME-2A/B: low R2 are already found for eCF > 10% HCHO products for eCF < 30% should be used for the three satellite instruments.

  17. 2. Validation of the satellite products——Wuxi station • Comparisons of daily averaged HCHOVCD between MAX-DOAS and three satellite for eCF<10% in Wuxi from 2011 to 2014 from 2011 to 2014

  18. 2. Validation of the satellite products——Wuxi station • NO2 VCD：bi-monthly averaged tropospheric VCDs for eCF<30% for the coincident observations of the satellite instruments and MAX-DOAS from 2011 to 2014 1、OMI good agreement with the MAX-DOAS VCDs 2、 GOME-2A and GOME-2B VCDs are systematically larger than the MAX-DOAS VCDs by about 5×1015 molecules cm-2 on average

  19. 2. Validation of the satellite products——Wuxi station • SO2 VCD：bi-monthly averaged tropospheric VCDs for eCF<30% for the coincident observations of the satellite instruments and MAX-DOAS from 2011 to 2014 1、The best agreement with MAX-DOAS results is found for the OMI BIRA product 2、SO2 large differences (about 20×1015 molecules cm-2) between the absolute values of the satellite and MAX-DOAS results

  20. 2. Validation of the satellite products——Wuxi station • HCHO VCD：bi-monthly averaged tropospheric VCDs for eCF<30% for the coincident observations of the satellite instruments and MAX-DOAS from 2011 to 2014 1、Relatively good agreement between the satellite and MAX-DOAS observations of HCHO 2、GOME-2A/B products are consistent with each other but have a strongly underestimate than OMI product especially in summer

  21. 2. Validation of the satellite products——Wuxi station Profiles from MAX-DOAS in Wuxi • Below 1.5km, most of information from measurements • The profile shapes: Aerosol: box+ exponential NO2: exponential SO2: exponential but higher layer HCHO: highest value at the surface + box up to 1km • Different seasons: Shapes similar, different absolute value

  22. 2. Validation of the satellite products——Hefei station • NO2 VCD: The R2, slopes and intercepts of the linear regressions, the MRD as well as the number of available days for the three satellite products with MAX-DOAS for six eCF bins form 2014 to 2016. OMI: R2 decrease with increasing eCF for eCF<30% GOME-2A/B:generally lower R2 is found for eCF<40% GOME-2A/B:the MRD indicates an increasing systematic overestimation

  23. 2. Validation of the satellite products——Hefei station Comparisons of daily averaged NO2 VCD between MAX-DOAS and three satellite for eCF<10% in Hefei form 2014 to 2016. higher correlation coefficients R2 for OMI than for GOME-2A/B

  24. 2. Validation of the satellite products——Hefei station • NO2 VCD：bi-monthly averaged tropospheric VCDs for eCF<30% for the coincident observations of the satellite instruments and MAX-DOAS from 2014 to 2016

  25. 2. Validation of the satellite products——Shanghai station • NO2 VCD: The R2, slopes and intercepts of the linear regressions, the MRD as well as the number of available days for the three satellite products with MAX-DOAS for six eCF bins form May 2012 to December 2015. OMI: R2 decrease with increasing eCF for eCF<40% GOME-2A:generally lower R2 is found for eCF<40% GOME-2A/B:the MRD indicates systematic overestimation

  26. 2. Validation of the satellite products——Shanghai station • Comparisons of daily averaged NO2 VCD between MAX-DOAS and three satellite for eCF<10% in Shanghai form May 2012 to December 2015. Better correlation coefficient for OMI and GOME-2A.

  27. 2. Validation of the satellite products——Shanghai station • NO2 VCD：bi-monthly averaged tropospheric VCDs for eCF<30% for the coincident observations of the satellite instruments and MAX-DOAS fromMay 2012 to December 2015.

  28. 3. Compare chemistry transfer model(CMT)data with MAX-DOAS For the daily comparisons, the CTM and MAX-DOAS results are averaged in the time periodof 8:00 to 16:00 local time. Skip the days when the MAX-DOAS results did not cover every 2-hour grid during a day.

  29. 3. Compare CTM data with MAX-DOAS——Wuxi Station 1)Lotos-Euros Daily mean near-surface NO2, SO2 and HCHO VMR from MAX-DOAS and LOTOS-EUROS model from 2011 to 2013 • Well consistency for edgar inventary • Best agreement found for HCHO VCD • Different measured air layer: LOTOS-EUROS (0-25meters), MAX-DOAS (0-200meters). Cause some errors.

  30. 3. Compare CTM data with MAX-DOAS——Wuxi Station 1)Lotos-Euros Scattered plots of the daily mean values from Lotos-Euros against those from MAX-DOAS for NO2 VCD, near-surface NO2 VMR, near-surface SO2 VMR and HCHO VCD, respectively, in the period from April 2 to June 30 2014. • NO2: • R2<0.13 • SO2: • R2<0.05 • HCHO: • R2 is 0.38 and 0.53 for the edgar and meric simulations

  31. 3. Compare CTM data with MAX-DOAS——Wuxi Station 1)Lotos-Euros The averaged diurnal variations of NO2 VCD, near-surface NO2 VMR, near-surface SO2 VMR and HCHO VCD are compared between from Lotos-Euros and from MAX-DOAS for respectively, in the period from April 2 to June 30 2014. • The simulations can well represent the diurnal variations for NO2 and HCHO, but not for SO2.

  32. 3. Compare CTM data with MAX-DOAS——Wuxi Station 2）CHIMERE Monthly mean near-surface NO2 VMR from MAX-DOAS and CHIMERE model from 2011 to 2013 • Well consistency • Different measured air layer: CHIMERE (0-600meters), MAX-DOAS (0-200meters). Cause some errors.

  33. 3. Compare CTM data with MAX-DOAS——Wuxi Station 2）CHIMERE Diurnal variations of near-surface NO2 VMR from CHIMERE model and from MAX-DOAS in different seasons. The the NO2 near-surface VMRs from CHIMERE model are obviously higher in the morning in all the seasons.

  34. 3. Compare CTM data with MAX-DOAS——Wuxi Station 3)IMAGES Monthly mean HCHO near-surface VMR and VCD from MAX-DOAS and IMAGES model from 2011 to 2013 daily mean HCHO VCD and near-surface (0-200 m) HCHO VMR monthly mean HCHO VCD and near-surface (0-200 m) HCHO VMR • Well consistency for monthly mean VCD and near-surface VMR • The standard simulations systematically underestimate the HCHO values obviously

  35. Conclusion and schedule • The tropospheric VCDs of NO2, SO2 and HCHO are measured by MAX-DOAS in Wuxi, Shanghai and Hefei stations from 2011 to 2016. • The tropospheric VCDs from MAX-DOAS are compared with OMI and GOME-2A/B in different cloud conditions, low CFs show good accordance. • The Profiles of NO2, SO2 and HCHO are retrieved, the VMR of the trace gases near surface can be retrieved and compared with the model simulations • The Profiles from MAX-DOAS can be used to modify the prior input for satellite to improve the precision.

  36. Thank you！

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