Impacts of land use and land cover changes on biogenic emissions of volatile organic compounds in China from the late 1980s to the mid-2000s: implications for tropospheric ozone and secondary organic aerosol

Abstract

A B S T R A C T Based on the MEGAN (Model of Emissions of Gases and Aerosols from Nature) module embedded within the global chemical transport model (GEOS-Chem), we estimate the changes in emissions of biogenic volatile organic compounds (BVOCs) and their impacts on surface-layer O 3 and secondary organic aerosols (SOA) in China between the late 1980s and the mid-2000s by using the land cover dataset derived from remote sensing images and land use survey. The land cover change in China from the late 1980s to the mid-2000s can be characterised by an expansion of urban areas (the total urban area in the mid-2000s was four times that in the late 1980s) and a reduction in total vegetation coverage by 4%. Regionally, the fractions of land covered by forests exhibited increases in southeastern and northeastern China by 10Á30 and 5Á15%, respectively, those covered by cropland decreased in most regions except that the farmingÁpastoral zone in northern China increased by 5Á20%, and the factions of grassland in northern China showed a large reduction of 5Á30%. With changes in both land cover and meteorological fields, annual BVOC emission in China is estimated to increase by 11.4% in the mid-2000s relative to the late 1980s. With anthropogenic emissions of O 3 precursors, aerosol precursors and aerosols fixed at year 2005 levels, the changes in land cover and meteorological parameters from the late 1980s to the mid-2000s are simulated to change the seasonal mean surface-layer O 3 concentrations by (4 to '6 ppbv ((10 to '20%) and to change the seasonal mean surface-layer SOA concentrations by (0.4 to '0.6 mg m (3 ( (20 to '30%) over China. We find that the decadal changes in meteorological parameters had larger collective effects on BVOC emissions and surface-layer concentrations of O 3 and SOA than those in land cover and land use alone. We also perform a sensitivity simulation to compare the impacts of changes in anthropogenic emissions on concentrations of O 3 and SOA with those of the changes in meteorological parameters and land cover.

Impact of climate and land cover changes on tropospheric ozone air quality and public health in East Asia between 1980 and 2010

“…1b). The enhanced summertime LAI is likely a result of warming and CO 2 fertilization, which promotes plant growth as is shown by a number of vegetation modeling studies (Gonzales et al, 2008;Kaplan et al, 2012). The pattern of satellite-derived LAI changes used in this study generally agrees with the changes derived from PFT-specific LAIs sim- ulated by these vegetation models between 1980 and 2010.…”

“…Although such replacement is not characteristic of the history (2014), our simulated impacts of LCLU on surface ozone are generally larger over China. Fu and Liao (2014) primarily considered the roles of vegetation distribution in affecting biogenic VOC emissions only. Our results demonstrate that dry deposition and vegetation density are equally, and potentially more, important in shaping ozone air quality in East Asia depending on the region.…”

“…There are only a limited number of studies quantifying how such historical changes might have affected ozone air quality in East Asia. Fu and Liao (2014) found that seasonal mean surface ozone changes within −4 to +6 ppbv in China between the late 1980s and mid-2000s due to changes in biogenic VOC emissions driven by climate and land cover changes. This study considered only historical changes in fractional coverage of plant functional type (PFT), but not in leaf area index (LAI), dry deposition, and soil NO x emission, all of which could have large impacts on the local chemical environments and thus ozone air quality.…”

Simulated contrasting influences of two La Niña Modoki events on aerosol concentrations over eastern China

“…Moreover, the GEOS-Chem model has been widely used in the atmospheric sciences and beyond and proven to be a useful tool for understanding the variability of aerosol concentrations. The model performance within East Asia has been evaluated in many recent studies [e.g., Fu and Liao, 2014;Mu and Liao, 2014;Lou et al, 2014;Feng et al, 2016c] that have shown that the seasonal and interannual variations of aerosol concentrations and ozone over eastern China are well captured in GEOS-Chem [e.g., Wang et al, 2011;Yang et al, 2014;Feng et al, 2016a].…”

Substantial ozone enhancement over the North China Plain from increased biogenic emissions due to heat waves and land cover in summer 2017

“…At the same time, such meteorological conditions also promote emissions of BVOC and ozone formation (Zhang and Wang, 2016). Using a global model, Fu and Liao (2014) suggested a slight to moderate increase in biogenic isoprene west and north of Beijing due to land cover and land use alone and an even more obvious increase when meteorological changes are considered. In the summer of 2017, heat waves swept over the majority of the NCP, providing an excellent opportunity to investigate how the heat wave may have modulated BVOC emissions and subsequent severe ozone events in the NCP.…”