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Hester Volten , Ellen Brinksma, Stijn Berkhout, Daan Swart, René van der Hoff,

NO 2 lidar profiles measured during the DANDELIONS validation campaign 2006. Hester Volten , Ellen Brinksma, Stijn Berkhout, Daan Swart, René van der Hoff, Hans Bergwerff, Pieternel Levelt, Gaia Pinardi, Michel Van Roozendael. CESAR . Clean air. Cabauw. industry. industry.

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Hester Volten , Ellen Brinksma, Stijn Berkhout, Daan Swart, René van der Hoff,

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  1. NO2 lidar profiles measured during the DANDELIONS validation campaign 2006 Hester Volten, Ellen Brinksma, Stijn Berkhout, Daan Swart, René van der Hoff, Hans Bergwerff, Pieternel Levelt, Gaia Pinardi, Michel Van Roozendael

  2. CESAR Clean air Cabauw industry industry DANDELIONS Sept. 2006 – Objectives Dutch Aerosol and Nitrogen Dioxide Experiments for vaLIdation of OMI and SCIAMACHY • O3 : total column and profile (sondes) • tropospheric contribution • NO2: lower tropospheric profile (lidar) • total columns (focus: pollution) • MAXDOAS intercomparison • Aerosol: radiosondes, CIMEL, SPUV, • aethalometer • CESAR site (Cabauw, 51.971°N, 4.927°E) • many continuous measurements • full meteorological info at location • 2007 research questions (for NO2): • Shape of NO2 profiles (and influence • on OMINO2) for industrial area • 2) Homogeneity of the NO2 field industry “How representative is an OMI measurement for surface concentrations?”

  3. Participating Institutes and Instruments OMI, SCIAMACHY RIVM NO2 lidar, NO2 in-situ monitors, boundary layer lidar BIRA-IASB MAXDOAS, Mini MAXDOASIUP Heidelberg MAXDOAS (three directions)IUP Bremen MAXDOAS NASA-GSFC Direct Sun Instrument (Pandora)KNMI Mini MAXDOAS, ozone sondes, radio sondes TNO Sun photometers, volatility system, aethalometer, nephelometer, etc.Nine validation days on Sept 8-13, 20-22Data publicly available on AVDC http://avdc.gsfc.nasa.gov

  4. The third dimension:NO2 lidar – ground level to about 2.5 kmNO2 in-situ monitor - on the ground and at 200 m Mini MAXDOAS - on the mast (200m)

  5. telescope Rapid switching between two wavelengths Mobile NO2 Lidar

  6. How to Measure a Profile 300 m

  7. NO2 Lidar Measurements during the DANDELIONS campaign • NO2 profiles during overpasses – seven different elevations 0.75, 1.5, 3, 6, 12, 24, 90 deg, 1 azimuth (39 degrees) • Spatial variations – two azimuths (39 and -36 deg), 1 elevation (12 degrees) • Time variations – 1 azimuth (39 degrees) , 1 elevation (12 degrees), long time series EXAMPLE: 12 SEPTEMBER in-situ monitor comparison Mini MAXDOAS heterogeneity

  8. Profile shape influences OMI retrieval 1500 Overview of all NO2 lidar measurements September 2006 Profile assumed in OMI retrieval 1000 Altitude (m) 500 10 30 40 0 20 50 60 concentration NO2 (mg/m3)

  9. OMI L4 tropospheric columns 12 September-polluted day

  10. NO2 lidar profile compares well with in-situ data

  11. 0,1,2,3,4,5,6,8,10, 12,14,16,20,25,30 Zenith -10,-8,-6,-4,-3,-2,-1 Example Mini MAXDOAS measurementHigh sensitivity to the vertical NO2 distribution in the lowest 200 m Julian day

  12. Boundary layer growth NO2 layer below 200 m NO2 layer above 200 m

  13. NO2 lidar profile comparesbadlywith in-situ data OMI overpass 12:47 UT

  14. Heterogeneity on 12 SeptemberNO2 lidar - different azimuth angles elevation 12 deg

  15. Heterogeneity on 12 SeptemberNO2 lidar - time series elevation 12 deg

  16. No problem Problem ! Lidar values smaller or the same as in-situ values

  17. Lidar versus in-situNH3 interference in-situ monitors? No solution: Error through NH3 interference cannot be larger than 6%

  18. Conclusions • We had a hugely successful DANDELIONS campaign in 2006. Data is available on AVDC. • NO2 lidar profile shapes differ quite a lot from OMI assumption • Concentrations on clear and polluted days show large variations, from ~3 to ~50 mg/m3 • Heterogeneity in space and time is sometimes very large • In-situ data and lidar data do not always agree

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