The DANDELIONS (Dutch Aerosol and Nitrogen Dioxide Experiments for vaLIdation of OMI and SCIAMACHY) project encompasses validation of OMI, SCIAMACHY of nitrogen dioxide (NO2) over the Netherlands.
Description of the campaigns
Two measurement campaigns took place in Cabauw (52° N, 5° E, The Netherlands), one from May to July 2005, and the second in September 2006, gathering in a synergistic way several type of ground-based measurement techniques (http://www.knmi.nl/omi/research/validation/dandelions).
View of the Cabauw site
Overview and first results are presented in Brinksma et al., 2008, while the entire dataset is accessible on the AVDC (Aura Validation Data Center) website.
BIRA-IASB participated with a MAXDOAS instrument in 2005 and with 2 MAXDOAS (one at ground and one at 200m height) and a newly developed DirectSun instrument in 2006, with main focuses on intercomparison of MAXDOAS technique (2 other MAXDOAS measuring simultaneously, operated by the university of Bremen and the university of Heidelberg), satellite validation and study of vertical and horizontal inhomogeneities in the tropospheric NO2 field, with particular interest in the Boundary Layer (BL).
Scientific highligthsAn example of temporal variation of the NO2 in showed in figure 1, while the impact of the horizontal inhomogeneities can be seen in figure 2 where the different MAXDOAS are compared one to the other, including the Heidelberg instrument that is simultaneously measuring in 3 azimutal directions.
Figure 1: Examples of tropospheric NO2 daily time-series, including the 3 MAXDOAS ground-based data and the closest OMI and SCIAMACHY cloud free overpass.
Figure 2: Scatter plots of the tropospheric NO2 retrieved from the ground-based MAXDOAS. BIRA and Bremen instruments were looking almost in the same direction (SW) while the Heidelberg instrument was simultaneously looking into 3 directions. For further details, see Brinksma et al. (2008). //Brinksma et al. (2008)//?>
These inhomogeneities have a large impact in the context satellite validation, where the local columns retrieval from the ground-based instruments are compared to NO2 columns values averaged within an horizontal extended pixel of several tens of km2 at best (OMI pixel: 13x24km2, SCIAMACHY pixel: 60x30km2). Detailed information can be found in Brinksma et al. (2008) and in Celarier et al. (2008) for the OMI validation, and in Pinardi et al. (in preparation) including SCIAMACHY.
List of publications
Brinksma, E., G. Pinardi, R. Braak, H. Volten, A. Richter, A. Schönhardt, M. Van Roozendael, C. Fayt, C. Hermans, R. Dirksen, T. Vlemmix, A.J.C Berkhout, D.P.J. Swart, H. Oetjen, F. Wittrock, T. Wagner, O. W. Ibrahim, G. de Leeuw, M. Moerman, L. Curier, E. A. Celarier, W. H. Knap, J. P. Veefkind, H.J. Eskes, M. Allaart, R. Rothe, A. J. M Piters, and P. Levelt (2008), The 2005 and 2006 DANDELIONS NO2 and Aerosol Intercomparison Campaigns, J. Geophys. Res., 113, D16S46, http://dx.doi.org/10.1029/2007JD008808
Celarier, E. A., E. J. Brinksma, J. F. Gleason, J. P. Veefkind, A. Cede, J. R. Herman, D. Ionov, F. Goutail, J.-P. Pommereau, J.-C. Lambert, M. van Roozendael, G. Pinardi, F. Wittrock, A. Schönhardt, A. Richter, O. W. Ibrahim, T. Wagner, B. Bojkov, G. Mount, E. Spinei, C. M. Chen, T. J. Pongetti, S. P. Sander, E. J. Bucsela, M. O. Wenig, D. P. J. Swart, H. Volten, M. Kroon, and P. F. Levelt (2008), Validation of Ozone Monitoring Instrument nitrogen dioxide columns, J. Geophys. Res., 113, D15S15, http://dx.doi.org/10.1029/2007JD008908
Hains, J., F. Boersma, M. Kroon, R. Dirksen, R. C. Cohen, A. Perring, E. Bucsela, H. Volten, D. Swart, A. Richter, F. Wittrock, A. Schoenhardt, T. Wagner, O. Ibrahim, M. Van Roozendael, G. Pinardi, J. F. Gleason, J. Veefkind, and P. Levelt (2010), Testing and improving OMI DOMINO tropospheric NO2 using observations from the DANDELIONS and INTEX-B validation campaigns, J. Geophys. Res., 115, D05301, doi:10.1029/2009JD012399.