Quantifying the impact of terrain–wind–governed close-effect on atmospheric polluted concentrations

Abstract

Rapid global urbanization and industrial expansion have resulted in severe atmospheric pollution sceneries in the past decades. Apart from the direct influence of anthropogenic emissions, the coupling of terrain and meteorological parameters may be another critical natural factor that indirectly impacts the dynamic polluted levels by means of terrain, wind, and planetary boundary layer governed accumulation and dilution in the horizontal and vertical dimensions. The nature-governed influence from the coupling of terrain and wind on air polluted levels can be called Terrain–Wind Close Effect (TWCE). As a value to represent the height of a geographic location above or below a fixed reference point, elevation cannot directly reflect the influence of terrain closed effect on air pollution levels at the regional/national scale. Therefore, this study aims to propose a Terrain–Wind Close Index (TWCI), which is a quantified comprehensive parameter of Earth terrain and atmospheric conditions controlling synergistically the localized or inhomogeneous concentration of fine particulate matters, to represent the nature-governed ability of terrain coupled with wind and boundary layer to block the dilution of contaminants. Results show a positive correlation (about 0.65) between TWCI and air polluted levels monitored by ground sites from January 1 to December 31, 2020 in China, which quantitatively exhibits that most of the high polluted levels existed in high-TWCI regions. The performance of the comprehensive TWCI in terms of its descriptive power on spatial pattern of surface polluted levels is superior to the single elevation (about 0.30) that widely used in previous studies. Moreover, the TWCI makes the static terrain dynamical by considering the synergistic effects of terrain and variational meteorological parameters on surface polluted levels. The newly proposed TWCI model has a potential to be applied to the research involve regional pollution estimation, environmental capacity assessment, urban planning and development, and so on.