The Vital Role of Biogenic Emissions from Urban Landscape in the formation of Ozone and SOA in Beijing

Abstract:

The biogenic emissions such as isoprene and monoterpene, plays crucial roles on the modulation of atmospheric chemistry in particular of the formation of ozone and secondary organic aerosols (SOA). However, the biogenic emissions released by urban landscape were largely ignored by the previous studies, yielding the abnormally low biogenic volatile organic compounds (BVOC) concentration in the urban area. In this study, the biogenic emissions from urban landscape were added in Beijing and the regional three dimensional air quality model WRF-CMAQ was used to investigate the effects of BVOC on the atmospheric oxidation as well as the subsequent influence on ozone and SOA formation in summer. Through the comparison with observations, we first illustrated that the diurnal cycle of isoprene is substantially improved by adding the BVOC released from the urban landscape. Secondly, the enhanced BVOC strikingly elevated the maximum daily 8-hr (MDA8) ozone in the urban of Beijing especially during the period when favorable meteorological conditions occur. Lastly, through compiling a large set of isoprene observations from the previous studies and comparison with the model results, we demonstrate that the missing urban BVOC emissions seems to be robust across many areas of China based on the common tool of Model of Emissions of Gases and Aerosols from Nature (MEGAN), which deserve a joint efforts of the community to construct the urban biogenic emissions, which can then be used to add on top of the current emissions generated from MEGAN.