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First results of the aerosol profiling group

This article presents the results of an aerosol intercomparison study conducted by various institutions. It discusses the challenges faced in measuring aerosol properties and proposes future plans for improving accuracy and sensitivity.

michaelandrew
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First results of the aerosol profiling group

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  1. First results of the aerosol profiling group IUP Heidelberg BIRA-IASB MPIC Mainz IUP Bremen JAMSTEC WSU KNMI NIWA Univ. Leicester PSI TNO RIVM KNMI

  2. The participants: MAX-DOAS • BIRA →aerosol extinction profiles→ UV and VIS →200m grid • IUP HDB →aerosol extinction profiles→ VIS→200m grid • JAMSTEC →aerosol extinction profiles→ VIS →1km grid; parameterized • MPI →aerosol extinction profiles→ UV →AOD + surface ext. + layer height + f=0.9 • IUP Bremen →AOD→VIS →?; parameterized

  3. The participants: • CIMEL sunphotometer (TNO) →AOD at different wavelengths & ssalb, phase-function • Nephelometer (PSI,TNO) →surface extinction & ssalb, phase-function • Ceilometer (KNMI) →boundary layer height • Backscatter lidar (RIVM) →boundary layer height • Ramen LIDAR (RIVM) →aerosol extinction profiles • …

  4. Results; BIRA

  5. AOD time series

  6. AOD time series

  7. AOD MAXDOAS vs. CIMEL

  8. AOD MAXDOAS vs. CIMEL Measured O4 DSCD are reduced by ~20% for BIRA, MPI, IUP HDB Not for JAMSTEC and IUP Bremen

  9. AOD MAXDOAS vs. CIMEL With correction Without correction

  10. Correcting the O4 DSCD

  11. Correcting the O4 DSCD Based on the Beijing dataset Case: 30° elevation , pointing north, clear-sky , AOD<0.15 →Measured and simulated O4 DSCD should be equal But sim. O4 DSCDs = meas. O4 DSCDs * 0.80.1

  12. Direct sun results VIS; Elena Spinei Measured DS SCDO4 is within 2% of the simulated using Hermans et al. cross section at room T (477 nm). 12

  13. Correcting the O4 DSCD ? Are we really sure that the simulations are correct . That the differences are not caused by errors in other forward model parameters No Yes Aerosol optical properties, … Error in measured O4 DSCD or Error in the spectra Error in DOAS fit ? O4 cross-section ? ?

  14. Influence of ssalb and g

  15. Contour plots Heidelberg VIS BIRA VIS JAMSTEC VIS

  16. Contour plots MPI UV BIRA UV

  17. Contour plots; identical scales BIRA VIS Heidelberg VIS JAMSTEC VIS

  18. Contour plots; identical scales BIRA UV MPI UV But; better results for f=1.1 Uplifted aerosol layer

  19. Contour plots BIRA VIS Heidelberg VIS JAMSTEC VIS

  20. Contour plots BIRA UV MPI UV

  21. Contour plots; identical scales BIRA VIS Heidelberg VIS JAMSTEC VIS

  22. Contour plots; identical scales BIRA UV MPI UV

  23. Aerosol inter-comparisons: plans for the future MAXDOAS → Focus on both AOD and profiles Retrieving synthetic profiles: • BIRA will provide O4 DSCDs and relative intensities at 4 wavelengths for 4 aerosol cases: low AOD and high AOD; surface layer and up-lifted layer • Try to retrieve the profiles using your best settings; the settings agreed on for the real data.

  24. Aerosol inter-comparisons: plans for the future Real data • On your own data set • On the Heidelberg dataset (data until October the 5th) • Retrievals using your own best settings • Retrievals using settings as similar as possible • Apriori extinction: exponential profile, SH=1km, AOD=0.1; • Height grid for the simulations: 200m grid to 4km. • Covariance matrix: 100% of apriori; 100m or 500m (HDB suggestion). • Atmosphere (P,T): USstandard • O3+NO2: USstandard • Lambertian surface albedo: 5% • Aerosol: optical properties are based on mean Nephelometer: g=0.65 and single scattering albedo = 0.95; • wavelengths: 360, 477, 577, 630nm if possible + Sensitivity tests concerning ssalb, phase function,…

  25. Aerosol inter-comparisons: plans for the future MAXDOAS vs other instruments • Insitu data, nephelometer (Paul Zieger) • Aerosol extinction from Raman LIDAR (Arnoud Apituley) Paper on MAXDOAS intercomparison and the Nephelometer paper by June-July →deadline for data submission: end March

  26. Summary The agreement between the different aerosol retrievals has already improved compared to the previous workshop Questions What’s up with the O4 DSCD? What can we actually achieve? (what is our sensitivity, how sensitive are we towards forward model parameters and towards a-priori information, can we obtain “substitute aerosol profiles” for clouds,…) Conclusion for now We are making progress But we still have a lot of work to do; a lot of questions to answer

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