Impacts of global biogenic isoprene emissions on surface ozone during 2000–2019

Biogenic isoprene is an important precursor of tropospheric ozone (O3). Here, a coupled chemistry–vegetation model was used to quantify the contributions of isoprene emissions to surface O3 pollution on the global scale during 2000–2019. The biogenic isoprene emissions showed high values in mid–low latitudes and seasonal peaks in the summer hemispheres. They promote global surface O3 concentrations by 1.75 ppbv annually with regional hotspots of 4.39 ppbv (8.8%) in China and 5.36 ppbv (11.1%) in the U.S. in boreal summer. In the past two decades, isoprene emissions increased by 1.32 TgC yr−1 (0.67% yr−1) in the Northern Hemisphere but decreased by 0.71 TgC yr−1 (0.44% yr−1) in the Southern Hemisphere. Such changes of isoprene made opposite contributions to the surface O3 trend, with 0.26 ppbv yr−1 in eastern China but −0.32 ppbv yr−1 in the southeastern U.S. due to the changes in the background regime of chemical reactions. The impact of anthropogenic changes on the O3 trend is consistent with that of biogenic isoprene, but two to four times stronger in magnitude. Our study revealed that the effective control of anthropogenic NOx emissions could mitigate regional O3 pollution even with the increased isoprene emissions under global warming. 植物源异戊二烯是对流层臭氧的重要前体物.本文通过一套耦合的大气化学-植被模式量化了2000-2019年全球异戊二烯排放对地表臭氧的影响.植物源异戊二烯在中低纬度地区排放较多, 并在夏半球达季节性峰值.它使全球年均臭氧浓度增高1.75 ppbv, 其中导致中国和美国夏季臭氧增长较多, 分别为4.39 ppbv (8.8%) 和5.36 ppbv (11.1%).过去20年, 北半球异戊二烯排放每年增加约1.32百万吨碳 (0.67% yr−1), 但南半球异戊二烯排放每年减少约0.71百万吨碳 (0.44% yr−1).由于化学反应背景场的不同, 异戊二烯变化对中国东部 (0.26 ppbv yr−1) 和美国东南部 (-0.32 ppbv yr−1) 地表臭氧趋势的贡献相反.人为源排放的变化对中国和美国地表臭氧趋势的贡献与异戊二烯的影响一致, 量级约为后者2∼4倍.研究表明, 尽管全球变暖背景下植物源异戊二烯排放增多, 减排人为源氮氧化物仍有助于缓解区域臭氧污染