Seasonality, trends, and SOA formation potential of anthropogenic volatile organic compounds: Implications for pollution

Abstract

Assessing the global distribution and characteristics of anthropogenic volatile organic compounds (AVOCs) is vital considering ongoing policy objectives. Due to the diversity in AVOCs emission sources and complex atmospheric transformation processes, understanding their seasonal cycles and role in forming secondary organic aerosol (SOA) is particularly important. We conducted a long-term analysis of ECHAM6-HAMMOZ (European Centre Hamburg version 6; HAM, Hamburg Aerosol Model; MOZ, Model for Ozone and related chemical tracers) model data, illustrating the spatial distribution of AVOCs simulated from 2001 to 2019. Sensitivity experiments involving doubling global anthropogenic volatile organic compounds emissions (DVOCS), compared to the control (CTL), reveal a significant increase (∼68 %) in AVOCs concentrations and pronounced seasonal variation during this period. Our findings show a rising trend in average AVOCs concentrations in Central Africa (∼0.003 ppb yr⁻¹), India (0.012 ppb yr⁻¹), and China (0.001 ppb yr⁻¹), alongside declines in the U.S. (−0.008 ppb yr⁻¹) and Europe (−0.01 ppb yr⁻¹) from 2001 to 2019. These regions exhibit high AVOCs concentrations from December to February and the lowest levels in June to August. Furthermore, doubling emissions results in an approximate ∼84 % increase in the secondary organic aerosol formation potential (SOAP) of AVOCs, with peak SOAP levels occurring during winter. Our study suggests that rising AVOCs emissions will enhance SOA formation, thereby increasing secondary particle pollution.