Daniel-Eduard CONSTANTIN^1*, Alexis MERLAUD², Mirela VOICULESCU¹, Michel VAN ROOZENDAEL², Maxim ARSENI¹, Adrian ROSU¹ & Lucian GEORGESCU^1
1"Dunarea de Jos", University of Galati, Faculty of Sciences and Environment, European Center of Excellence for the Environment, Str. Domneasca, Nr.111, Galati 800008, Romania; E-mail: daniel.constantin@ugal.ro
²Belgian Institute for Space Aeronomy, Ringlaan-3-Avenue Circulaire B-1180, Brussels 1180, Belgium

NO₂ AND SO₂ OBSERVATIONS IN SOUTHEAST EUROPE USING MOBILE DOAS OBSERVATIONS

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In this work we present the first and longest zenith-sky mobile DOAS (Differential Optical Absorption Spectroscopy) measurements performed in Southeast Europe. The mobile DOAS observations were performed on board of a motor vehicle using an UV-Vis spectrometer during several days on 2015 and 2016 in Romania, Bulgaria, Greece and Republic of Moldova. The target trace gases are: nitrogen dioxide (NO₂) and sulfur dioxide (SO₂). The mobile DOAS measurements performed on ground represents aproximative 1500 km travelled on roads. The highest tropospheric NO₂ (1x10¹⁷ molec./cm²) and SO₂ (~2.5x10¹⁸ molec/cm²) content was determined in the Jiu Valley Romania, where large fossil-fuel power station exist. The study also presents comparisons of tropospheric NO₂ Vertical Column Density (VCD) deduced from mobile DOAS measurements with Ozone Monitoring Instrument observations. We found a good agreement between ground and space observations for two important urban agglomerations. For Bucuresti city the averaged mobile DOAS observations function of OMI pixel coordinates show 4.11 (±0.61) x10¹⁵ molec/cm² while OMI detected 5.94 (±2.87) x10¹⁵ molec/cm². For the other important city, Thessaloniki, averaged mobile DOAS observations indicate 5.44 ± (0.84) x10¹⁵ molec/cm² while OMI space observations presents 5.66 (±1.56) x10¹⁵ molec/cm². We found also that due to the smoothing effect inside the pixel, OMI sensor underestimated the important NO₂ emissions located in the Jiu Valley, Romania.