Impact of Anthropogenic Emission Injection Height Uncertainty on Global Sulfur Dioxide and Aerosol Distribution

Abstract

Anthropogenic sulfur compounds play an important role in acid deposition, aerosol particle formation, and subsequent radiative forcing and human fine particulate exposure. There are substantial uncertainties in processes influencing sulfate and precursor distributions, however, that have not yet been resolved through comparisons with observations. We find here an underappreciated factor that has a large impact on model results: uncertain emission height. Global aerosol‐climate model simulations indicate that the assumed effective anthropogenic emission height is very important to SO2 near‐surface concentrations and vertical profile. The global range of near‐surface SO2 concentration over land (ocean) due to uncertainty in industrial (international shipping) emission injection height is 81% (76%), relative to the average concentration. This sensitivity is much larger than the uncertainty of SO2 emission rates. Black carbon and primary organic matter concentration and profiles are also sensitive to emission heights (53% over land and 28% over oceans). The impact of emission height uncertainty is larger in winter for land‐based emissions, but larger in summer over the Northern Hemisphere ocean for shipping emissions. The variation in aerosol optical depth related to shipping emission injection heights is 11% over oceans, revealing the potential importance of injection height on aerosol forcing and climatic effects. The large impact on SO2 concentrations can confound attempts to use surface, aircraft, and satellite observations to constrain the importance of other processes that govern sulfur compound distributions in the atmosphere. The influence of emission height on vertical SO2 column also will impact the accuracy of satellite retrievals.

Exploring 2016–2017 surface ozone pollution over China: source contributions and meteorological influences

“…S3 that observed MDA8 ozone concentrations in many cities can shift by more than 60 ppbv in 2 d. Such variations, however, are challenging for Eulerian chemical models to capture due to numerical diffusion, even at 10 km grid resolution, and representative issues when comparing gridded simulated results to observations at urban sites (Young et al, 2018). Artificial mixing of ozone precursors in model grids may cause higher ozone production efficiency and therefore positive ozone biases (Wild and Prather, 2006;Yu et al, 2016;Young et al, 2018). In addition, models have limited skills in presenting local emissions and meteorological conditions, particularly over complex terrain (e.g., in WCH and SCB cities) Ni et al, 2018).…”

Modeling diurnal variation of surface PM<sub>2.5</sub> concentrations over East China with WRF-Chem: impacts from boundary-layer mixing and anthropogenic emission

“…F. Wang et al, 2014;Chen et al, 2015;Geng et al, 2015;Li et al, 2015;Xie et al, 2015;Zhang and Cao, 2015;Chen et al, 2016). Moreover, modeling analysis can help understand the chemical and physical processes affecting aerosol formation and evolution (e.g., Ying et al, 2009;Zhang et al, 2010;Liao et al, 2014;Cheng et al, 2016;Yang et al, 2016;Zhao et al, 2017). Yang et al (2016) reproduced an increasing trend of winter PM 2.5 concentrations averaged over East China for 1985China for -2005 with the GEOS-Chem model and found that the variations in anthropogenic emissions dominated the increase in winter surface PM 2.5 concentrations over East China, and the variations in meteorological fields also played an important role in influencing the decadal increase in winter PM 2.5 concentrations over East China.…”

“…For meteorology, we will focus on the PBL mixing process that has been found to largely control the diurnal variation of surface pollutant concentrations (M. . For emissions, based on the findings of Wang et al (2010) and Yang et al (2019), the diurnal variation and injection height of emission will be investigated. The rest of the paper is organized as follows.…”

Trends and source apportionment of aerosols in Europe during 1980–2018

“…The decrease in aerosols over Europe was mainly attributed to continuous reductions in local European anthropogenic emissions of aerosols and precursor gases since the 1980s (Smith et al, 2011), which are a result of legislation for improving air quality. In addition to local emissions, aerosol levels can also be affected by aerosol transport at continental scales (Zhang et al, 2017;Yang et al, 2018a). Aerosol emissions in major economic regions of the world have been changing rapidly during the past few decades owing to economic development and environmental measures.…”