Validation of Ozone Monitoring Instrument NO2 measurements using ground based NO2 measurements at Zvenigorod, Russia

We present the results of comparison between Ozone Monitoring Instrument (OMI) data of NO2 measurements (Collection 3) onboard the NASA EOS-Aura satellite and correlative ground-based twilight measurements at Zvenigorod station in Russia in 2004-2008. Compared quantities are unpolluted column and tropospheric column amounts of NO2 which are standard products of OMI measurements. The NO2 columns observed by our ground-based instrument have been interpolated to the time of OMI measurements using a one-dimensional photochemical model. According to our comparison, the OMI unpolluted NO2 columns underestimate ground-based measurements by (0.084 +/- 0.025) x 10(15) molecules/cm(2), or (3.2 +/- 0.9)%. The correlation coefficient between the OMI and ground-based unpolluted NO2 columns is 0.92. The tropospheric NO2 columns derived from OMI measurements are on average by (1.8 +/- 0.5) x 10(15) cm(-2), or approximately 40%, less than those derived from ground-based measurements. The correlation coefficient between these data is about 0.3. Reasons for this discrepancy are discussed.