Profiling of SO2, NO2, and O3 in the lower troposphere by multiwavelength differential absorption lidar

We performed SO2, NO2, and O-3 measurements in the lower troposphere using a multiwavelength differential absorption lidar (MDIAL) system. Measurement results are compared with results of airborne and ground-based in-situ measurements performed simultaneously with lidar measurement. Vertical concentration variation Of SO2 with 0-7 ppb for 1000-1700 in altitude was measured by dual-DIAL, and those of NO2 and O-3 with 0-50 ppb for 700-2000 in altitude were measured by 2-wavelength DIAL quasi-simultaneously. Measurement results suggest that NO2 was trapped below the inversion layer, which induced the reduction of O-3 concentration by the reaction with NOx. Comparison of results obtained by DIAL and by in-situ methods showed that the MDIAL system had sufficient accuracy for verification of long-range transport models of sulfur compounds and for observation of chemical reactions of oxidants and nitrogen oxides. We also performed simultaneous profiling of NO2 and O-3 in the lower troposphere using a stable, high power transmitter for NO2 measurement. Concentration variations of NO2 and O-3 for 900-1350 m altitude were measured for a continuous time interval of 24 hours without maintenance.