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Status paper

Status paper. Internal review process until July 15 Send around to all authors, collect comments by August 10 Submit August 20. MAX-DOAS profile retrieval (I). Optimal Estimation using a priori information

erica-langley
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Status paper

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  1. Status paper • Internal review process until July 15 • Send around to all authors, collect comments by August 10 • Submit August 20

  2. MAX-DOAS profile retrieval (I) • Optimal Estimation using a priori information • Online calculation of block-AMFs and describe relation between measurements (SCDs of trace gas for different elevations) and absorber profile as a linear inversion problem: • Solve by Optimal estimation method (therefore adding a trace gas a priori profile) • BIRA, NIWA, WSU, Heidelberg, Leicester/Leeds and Bremen

  3. MAX-DOAS profile retrieval (II) • Inversion by parametrisation of trace gas profiles • A) mixing layer height MLH(important atmospheric parameter) • B) fraction f of total VCD in boundary layer (allows to adjust vertical profile, depending e.g. on vertical mixing into free troposphere) • Lookup tables for AMF, least squares fit • MPI Mainz, similar approach used by JAMSTEC, KNMI

  4. Data included – three-fold comparison Toidentifyeachmethodspossibilities Whatareprosandcons? Howconsistentaretheresults in the real world? How do theycomparetootherinstruments?

  5. Simulation study • IASB-BIRA has provided modeled NO2 slant columns for UV and visible, using • different NO2 scenarios (profiles) • Two aerosol loadings (AOD 0.14 and 0.54 for 477 nm) • Simulations for June 24, 2009 in Cabauw • 10 Elevation Angles (1,2,4,5,6,8,10,15,30,89) • SCD error based on real DOAS fit errors plus Gaussian noise • Calculations with RTM LIDORT

  6. Simulation study

  7. For all comparisons . .. • Wearefocusing on twoparameters: • Troposphericcolumn <-> importantforsatellitevalidation) • VMR closetothesurface <-> easy tocomparewith in situ data • MAX-DOAS as a link betweensatelliteand in situ (airpollution) network.

  8. VC and surface layer values usually captured well, difference to true value for most scenarios less than 25% Viewing directions towards sun (RAA < 20°) and for high SZA (>75°) for some algorithms difficult to retrieve LOS < 3° crucial for proper profile retrieval 1.5 < DoF < 3 Results in the visible have less scatter, in particular for high aerosol load (not surprising) Conclusions from simulation study

  9. „Best“ settingsfor OE: Finergridgivesmoredetails (shallowandveryshallowlayer) andforsomealgorithmsbetteragreement (Bremen, NIWA, WSU) toreferencedata From Bremen experiencetheretrievalprofitsfromusingbothwavelengthregions in parallel Conclusions from simulation study

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