Exploratory analysis of carbonaceous PM2.5 species in urban environments: Relationship with meteorological variables and satellite data

Abstract

The carbonaceous chemical composition and mass concentration of particles with an aerodynamic diameter less than 2.5 μm (PM2.5), were analyzed, as well as their relationship with satellite data and meteorological variables. PM2.5 ground samples were collected at nine sampling sites with different land use in the metropolitan area of Córdoba city, during autumn and winter in 2018, and concentrations of organic carbon (OC) and elemental carbon (EC) were measured. The aerosol optical depth (AOD) was retrieved from the MODIS sensor, Aqua and Terra satellites. The AOD was validated using ground-based sun photometer data. Furthermore, the PM2.5 mass concentration and composition were simulated using multiple linear regression models, with the measured AOD and meteorological parameters as input variables. The data showed that PM2.5 mass concentrations varied in space throughout the city, indeed at four sampling sites, they exceeded the World Health Organization (WHO) daily guidelines. The OC and EC mass concentrations were moderate and low, respectively, in comparison with other cities in the world. PM2.5 concentrations were negatively associated with average planetary boundary layer (PBLav), dew point (DP) and AOD from Aqua satellite (AODa). The columnar average AODav did not correlate significantly with the ground-based PM2.5 measurements, however AODa was retained in a model to explain PM2.5 having a negative effect on particles. An effective carbon ratio (ECR) was calculated to estimate the radiative forcing of PM2.5 in a local scale. The results suggested an overall local radiative heating effect due to PM2.5.