1Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium
2Rutherford Appleton Laboratory (RAL), Chilton, Didcot, UK
3Royal Netherlands Meteorological Institute (KNMI), De Bilt, the Netherlands
4Royal Meteorological Institute (KMI-IRM), Brussels, Belgium
5Laboratoire Atmosphère, Milieux, Observations Spatiales (LATMOS), Université Pierre et Marie Curie, Université Versailles St-Quentin-en-Yvelines, Centre National de la Recherche Scientifique, Paris, France
6Finnish Meteorological Institute (FMI-ARC), Sodankylä, Finland
7Federal Office of Meteorology and Climatology (MeteoSwiss), Payerne, Switzerland
8European Space Agency (ESA/ESRIN), Frascati, Italy
Received: 16 Sep 2014 – Discussion started: 21 Nov 2014
Abstract. A methodology for the round-robin evaluation and the geophysical validation of ozone profile data retrieved from nadir UV backscatter satellite measurements is detailed and discussed, consisting of data set content studies, information content studies, co-location studies, and comparisons with reference measurements. Within the European Space Agency's Climate Change Initiative on ozone (Ozone_cci project), the proposed round-robin procedure is applied to two nadir ozone profile data sets retrieved at the Royal Netherlands Meteorological Institute (KNMI) and the Rutherford Appleton Laboratory (RAL, United Kingdom), using their respective OPERA v1.26 and RAL v2.1 optimal estimation algorithms, from MetOp-A GOME-2 (i.e. the second generation Global Ozone Monitoring Experiment on the first Meteorological Operational Satellite) measurements taken in 2008. The ground-based comparisons use ozonesonde and lidar profiles as reference data, acquired by the Network for the Detection of Atmospheric Composition Change (NDACC), Southern Hemisphere Additional Ozonesonde programme (SHADOZ), and other stations of the World Meteorological Organisation's Global Atmosphere Watch (WMO GAW). This direct illustration highlights practical issues that inevitably emerge from discrepancies in e.g. profile representation and vertical smoothing, for which different recipes are investigated and discussed. Several approaches for information content quantification, vertical resolution estimation, and reference profile resampling are compared and applied as well. The paper concludes with compliance estimates of the two GOME-2 ozone profile data sets with user requirements from the Global Climate Observing System (GCOS) and from climate modellers.
Revised: 17 Apr 2015 – Accepted: 24 Apr 2015 – Published: 20 May 2015
Keppens, A., Lambert, J.-C., Granville, J., Miles, G., Siddans, R., van Peet, J. C. A., van der A, R. J., Hubert, D., Verhoelst, T., Delcloo, A., Godin-Beekmann, S., Kivi, R., Stübi, R., and Zehner, C.: Round-robin evaluation of nadir ozone profile retrievals: methodology and application to MetOp-A GOME-2, Atmos. Meas. Tech., 8, 2093-2120, doi:10.5194/amt-8-2093-2015, 2015.