Development of an Updated Isoprene Emission Inventory for China

Isoprene is the dominant non-methane Volatile Organic Compounds (VOCs) emitted from terrestrial ecosystems and plays an important role in ozone chemistry. Understanding isoprene emissions is critical for controlling air pollution. The Model of Emissions of Gases and Aerosols from Nature (MEGAN) is widely used to calculate biogenic isoprene emissions worldwide. While MEGAN predictions are good for many regions, a previous analysis of isoprene observations around China showed large discrepancies between observed and simulated isoprene concentrations. The uncertainties of isoprene emissions in China are also reflected in the large differences between MEGAN version 2.1 and 3.2. In this work, bottom-up high-resolution vegetation distributions and up-to-date emission factors are combined with satellite data in the Speciated isoprene emissions with the MEGAN Algorithm for China (SieMAC) to improve isoprene emission estimates in China. The results from this new emission inventory improve upon MEGAN version 2.1 and 3.2 when compared with isoprene observations. The improved emission inventory is applied in a regional model to quantify the biogenic contribution to ozone pollution in China.