Scanning and mobile multi-axis DOAS measurements of SO2 and NO2 emissions from an electric power plant in Montevideo, Uruguay

During the period of the campaign the mean SO2 emission flux was determined to be 0.36 (±0.12) kg s−1 and 0.26 (±0.09) kg s−1 retrieved from mobile and scanning DOAS respectively, while the calculated SO2 flux from the sulphur content of the fuel was 0.34 (±0.03) kg s−1. The average NO2 flux calculated from mobile DOAS was determined to be 11 (±3) × 10−3 kg s−1. Using the scanning DOAS approach a mean NO2 flux of 5.4 (±1.7) × 10−3 kg s−1 was obtained, which is significantly lower than by the mobile measurements. The differences between the results of mobile MAX-DOAS measurements and scanning DOAS measurements are most probably caused by the variability and the limited knowledge of the wind speed and direction.