The Impact of Southeast Asian Biomass Burning on CO Mixing Ratios in East Asia

To investigate the net influence of Southeast (SE) Asian biomass burning on CO mixing ratios over a specific region (20 - 30 N and110 - 130 E), Tropospheric Emission Spectrometer (TES) CO data, ground surface CO measurements at Yonagunijima (24.47 N, 123.02 E, 30 m asl, Japan) and Kenting (21.96 N, 120.53 E, 250 m asl, Taiwan), coupling with backward trajectories and fire spots analyses were applied in this study. The result indicated that neither of the ground observations showed elevated CO during intensive fire periods since the air masses in the northeastern monsoon season were predominately from Northern China and Korea/Japan. For a case study, high TES CO mixing ratios were observed at the altitude > 680 hPa during 4 - 10 March. Along Track Scanning Radiometer (ATSR) showed numerous fire spots in SE Asia, while the air parcels mainly originated from the SE Asian continent. It was also determined by MODIS image that the high CO concentrations over the middle troposphere were contributed by the biomass burning events. Finally, the air parcels from the SE quadrant were divided into two categories, those that passed over the fire regions (PF) and those that did not (NP). The result showed that the significant difference between NP and PF averaged ~ 50 ppb between 825 - 460 hPa (p < .05), whereas no obvious discrepancy was found in the upper troposphere during the biomass burning season. Although uncertainties existed in satellite data and trajectories, the investigation showed that the biomass burning impacted the CO mixing ratios in the lower/middle troposphere during their long-range transport.