- 期刊
Estimation of Biogenic VOC Emissions in East Asia with New Emission Factors and Leaf Energy Balance Considerations
摘要
A good inventory system of biogenic VOCs emissions in East Asia is required and must function correctly alongside available meteorological data to enable adequate estimation of biogenic emissions. There is a wide body of literature concerning estimations of biogenic emissions in East Asia or larger areas; however, many use environmental temperature rather than leaf temperature; further, they only focus on three kinds of biogenic VOCs: Isoprene, Monoterpenes and other BVOCs. This may cause estimation errors, the size of which are unclear. The purpose of this study is to establish an estimation model of biogenic VOC emissions for East Asia giving due consideration to the leaf energy system, ensuring it can be used effectively with appropriate meteorological data, while estimating hourly emissions of 33 specific species of biogenic VOCs from plants in East Asia. Estimation errors found using environmental temperature instead of leaf temperature were also investigated. Finally, uncertainty of estimation results was analyzed with regard to land use and emission factor datasets. Total annual BVOC emissions in East Asia (the domain of this study) estimated by the model established by this study can be up to 40.9 Tg yr^(-1) and are comprised of 24.6% isoprene, 45.1% of 14 species of monoterpenes, 28.9% of 17 species of other BVOCs and just 1.4% MBO. The replacement of leaf temperature with environment temperature results in overestimations of annual amounts for all BVOC species. Results indicated that total BVOC emissions were overestimated by 30.7%, with significant overestimations of isoprene, 46.7%, and a smaller but still significant overestimation of monoterpenes of around 24.2%. Not all areas exhibited overestimations as zonal and seasonal differences were influential. In summer, when leaf energy instead of ambient temperature was used, BVOC emissions in all areas of the simulation region were overestimated. In winter, overestimations appeared in areas at lower latitudes, and underestimations appeared in areas at higher latitudes. With regard to uncertainty, three different kinds of emission factors and two types of land use data were applied. Results showed that estimated emissions of BVOCs varied more than 200% when either emission factors or land use data were used. Besides, the daily maximum O_3 concentration changed significantly in some areas (-15 - 9 ppb). To reduce uncertainty in estimation results, a suitable database of land use and emission factors that gives consideration to vegetation features in different areas is required.