Long-term MAX-DOAS network observations of NO2 in Russia and Asia (MADRAS) during the period 2007ndash;2012: instrumentation, elucidation of climatology, and comparisons with OMI satellite observations and global model simulations

摘要

We conducted long-term network observations using standardized Multi-AxisDifferential optical absorption spectroscopy (MAX-DOAS) instruments in Russiaand ASia (MADRAS) from 2007 onwards and made the first synthetic dataanalysis. At seven locations (Cape Hedo, Fukue and Yokosuka in Japan, Hefeiin China, Gwangju in Korea, and Tomsk and Zvenigorod in Russia) withdifferent levels of pollution, we obtained 80 927 retrievals of troposphericNO vertical column density (TropoNO2VCD) and aerosol optical depth(AOD). In the technique, the optimal estimation of the TropoNO2VCD and itsprofile was performed using aerosol information derived from Oabsorbances simultaneously observed at 460–490 nm. This large data set wasused to analyze NO climatology systematically, including temporalvariations from the seasonal to the diurnal scale. The results were comparedwith Ozone Monitoring Instrument (OMI) satellite observations and globalmodel simulations. Two NO retrievals of OMI satellite data (NASA ver.2.1 and Dutch OMI NO (DOMINO) ver. 2.0) generally showed closecorrelations with those derived from MAX-DOAS observations, but had lowbiases of up to ~50%. The bias was distinct when NO wasabundantly present near the surface and when the AOD was high, suggesting apossibility of incomplete accounting of NO near the surface underrelatively high aerosol conditions for the satellite observations. Except forconstant biases, the satellite observations showed nearly perfect seasonalagreement with MAX-DOAS observations, suggesting that the analysis ofseasonal features of the satellite data were robust. Weekend reduction in theTropoNO2VCD found at Yokosuka and Gwangju was absent at Hefei, implying thatthe major sources had different weekly variation patterns. While theTropoNO2VCD generally decreased during the midday hours, itincreased exceptionally at urban/suburban locations (Yokosuka, Gwangju, andHefei) during winter. A global chemical transport model, MIROC-ESM-CHEM(Model for Interdisciplinary Research on Climate–Earth SystemModel–Chemistry), was validated for the first time with respect tobackground NO column densities during summer at Cape Hedo and Fukue inthe clean marine atmosphere.