Impacts of Changes in Land Use and Land Cover Between 2001 and 2018 on Summertime O₃ Formation in North China Plain and Surrounding Areas–A Case Study

Abstract

Changes in land use and land cover (LULC) influence meteorological fields and biogenic emissions, further affecting the atmospheric chemistry and air quality. Combining the satellite measurements and WRF‐Chem model simulations, we evaluate the impacts of the LULC change between 2001 and 2018 on the summertime ozone (O3) formation in North China Plain and surrounding areas (NCPs). Satellite measurements have revealed that from Taihang to Yanshan Mountain, the fraction of broadleaf and needle forest coverage has increased by 5%–20% and the urban area has increased by up to 25% in the NCP. Additionally, the vegetation density has increased significantly in the NCPs except for urban areas. The LULC change generally enhances biogenic volatile compounds emissions in the NCPs, particularly over Taihang and Yanshan mountain, but the O3 variation is divergent. The maximum daily 8‐ihr average (MDA8) O3 concentrations are reduced by 1%–7% over Taihang and Yanshan Mountain because the raised vegetation density increases O3 dry deposition velocity to accelerate the O3 loss. The raised vegetation density enhances the evapotranspiration to decrease the near‐surface temperature by 0.1°C–1.5°C, which also generates a divergence in the low‐level atmosphere in the NCPs, causing secondary northerly or easterly winds in the NCP. The O3 enhancement along the coastal areas of the NCP is attributed to the perturbation of wind fields and photolysis induced by the LULC change. The divergent variation of the MDA8 O3 concentrations in the NCP is generally caused by the variations of biogenic emissions and photolysis.

Impact of Particulate Matter-Centric Clean Air Action Plans on Ozone Concentrations in India

“…In general, the increase in forest cover is associated with enhanced biogenic VOCs, which may lead to increased ozone levels; however, this change in LULC also results in an increased dry deposition velocity of ozone, consequently accelerating ozone loss. This inference is supported by a study over China, stating the divergent variation noted in the maximum daily 8 h average ozone concentrations due to change in LULC. Thus, it is vital to give due consideration to changes in LULC patterns and understanding its impact on atmospheric chemistry along with a reduction in emissions to curb air pollution.…”

“…The chemistry of ozone is nonlinear and as stated earlier dependent on various factors . The LULC is one such factor that affects ambient ozone levels due to its influence on biogenic emissions, meteorological parameters, and deposition velocity of ozone . In addition to the reduction of anthropogenic emissions from varied sectors, India’s NCAP also includes the maintenance of 33% forest cover and the creation of green buffers .…”

“…58 The LULC is one such factor that affects ambient ozone levels due to its influence on biogenic emissions, meteorological parameters, and deposition velocity of ozone. 59 In addition to the reduction of anthropogenic emissions from varied sectors, India's NCAP also includes the maintenance of 33% forest cover and the creation of green buffers. 10 Thus, to understand the impact of LULC on ozone concentrations, additional simulation is performed for the year 2024 with LULC of 2019 for summer and winter.…”