Isoprene Emissions Response to Drought and the Impacts on Ozone and SOA in China. Issue 10 (17th May 2021)

• Record Type: Journal Article
• Authors: Wang, Peng; Liu, Yiming; Dai, Jianing; Fu, Xiao; Wang, Xuemei; Guenther, Alex; Wang, Tao
• Is Part Of: Journal of geophysical research. Volume 126:Issue 10(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-05-17
• Subjects: CMAQ -- drought response -- isoprene -- MEGAN -- ozone -- SOA; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1029/2020JD033263
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: Among the various environmental factors that affect isoprene emissions, drought has only been given limited attention. Four different drought response (DR) schemes were implemented in the Model of Emissions of Gases and Aerosols from Nature (MEGAN, version 2.1), and the Community Multiscale Air Quality (CMAQ) model was applied to investigate the drought impacts on air quality during both drought and normal years in China. Generally, all DR schemes decrease isoprene emissions except for mild drought conditions. The significant decrease and even termination of isoprene emissions are predicted in South China under severe drought conditions. During the drought period, the DR scheme considering both mild and severe drought (SMD) improves the model performance especially in severe drought‐hit regions when compared with the Ozone Monitoring Instrument (OMI) averaged formaldehyde vertical column density (HCHO VCD). The results show that most of the DR schemes decrease simulated ozone (O3 ) and secondary organic aerosols (SOA) levels. For both O3 and SOA, noticeable changes are predicted in the Sichuan Basin (5 ppb and 4 µg m −3 for O3 and SOA, respectively). This investigation is the first modeling study to investigate the impacts of isoprene drought response on air quality in China. Plain Language Summary: In the last 50 years, drought has become more severe, prolonged, and frequent in China, which is expected to affect air quality by changing Biogenic volatile organic compound (BVOC) emissions. The BVOCs are regarded as the significant precursor of secondary pollutants such as O3 and secondary organic aerosols (SOA), and thus play an important role in the air quality. This is the first modeling study to evaluate drought impacts on atmospheric chemistry and air quality in China using different isoprene drought response schemes. The drought scheme considering both mild and severe drought has improved the model performance at severe drought‐hit regions when compared with the satellite formaldehyde vertical column density. Most of the drought schemes predict lower isoprene emissions and thus leading to lower O3 and SOA levels. During the drought year, O3 and SOA decreases of up to −8% and −30% are simulated for southern China under severe drought conditions. Key Points: First implementation of the Model of Emissions of Gases and Aerosols from Nature (MEGAN) model drought response for investigating China air quality The drought scheme considering both mild and severe drought improves the model performance in severe drought‐hit regions Prominent changes of O3 (−8%) and secondary organic aerosols (SOA) (−30%) are predicted in the drought year in southern China