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Published byMorgan Henry Modified over 8 years ago
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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
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The participants: MAX-DOAS JAMSTEC → aerosol extinction profiles → VIS → 1km grid; parameterized IUP HDB → aerosol extinction profiles → VIS → 200m grid BIRA → aerosol extinction profiles → UV and VIS → 200m grid MPI → aerosol extinction profiles → UV → AOD + surface ext. + layer height + f=0.9 IUP Bremen → AOD → VIS → ?; parameterized
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CIMEL sunphotometer (TNO) → AOD at different wavelengths & ssalb, phase-function Nephelometer (PSI,TNO) → surface extinction & ssalb, phase-function Ramen LIDAR (RIVM) → aerosol extinction profiles Ceilometer (KNMI) → boundary layer height Backscatter lidar (RIVM) → boundary layer height The participants: …
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Results; BIRA
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AOD time series
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AOD MAXDOAS vs. CIMEL
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Measured O 4 DSCD are reduced by ~20% for BIRA, MPI, IUP HDB Not for JAMSTEC and IUP Bremen
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With correctionWithout correction AOD MAXDOAS vs. CIMEL
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Correcting the O 4 DSCD
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Case: 30° elevation, pointing north, clear-sky, AOD<0.15 Correcting the O 4 DSCD Based on the Beijing dataset → Measured and simulated O 4 DSCD should be equal But sim. O 4 DSCDs = meas. O 4 DSCDs * 0.8 0.1
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12 Measured DS SCD O4 is within 2% of the simulated using Hermans et al. cross section at room T (477 nm). Direct sun results VIS; Elena Spinei
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Correcting the O 4 DSCD ? Are we really sure that the simulations are correct. That the differences are not caused by errors in other forward model parameters Aerosol optical properties, … Error in measured O 4 DSCD Error in the spectra Error in DOAS fit ? O 4 cross-section No Yes or ? ?
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Influence of ssalb and g
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BIRA VIS Heidelberg VIS JAMSTEC VIS Contour plots
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BIRA UV MPI UV Contour plots
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BIRA VIS Heidelberg VIS JAMSTEC VIS Contour plots; identical scales
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BIRA UV MPI UV But; better results for f=1.1 Uplifted aerosol layer Contour plots; identical scales
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BIRA VIS Heidelberg VIS JAMSTEC VIS Contour plots
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BIRA UVMPI UV Contour plots
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BIRA VIS Heidelberg VIS JAMSTEC VIS Contour plots; identical scales
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BIRA UV MPI UV Contour plots; identical scales
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Aerosol inter-comparisons: plans for the future Retrieving synthetic profiles: BIRA will provide O 4 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. MAXDOAS → Focus on both AOD and profiles
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+ Sensitivity tests concerning ssalb, phase function,… 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
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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 Aerosol inter-comparisons: plans for the future
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Summary The agreement between the different aerosol retrievals has already improved compared to the previous workshop Questions What’s up with the O 4 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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