Spatial-temporal characteristics of the air quality in the Guangdong - Hong it Kong - Macau Greater Bay Area of China during 2015-2017

Spatial-temporal characteristics of the air quality including size-segregated particulate matter (PM) portions and ozone (O-3) in the Guangdong-Hong Kong -Macao Greater Bay Area (GBA) of China are analyzed using daily observational data during 2015-2017. A big picture of multiple years' in situ observational air quality in GSA is provided. A collection of three neighboring cities Foshan (FS), Guangzhou (GZ), and Dongguan (DG), referred to as FGD, on average has the worst air quality in GBA, mostly due to the heavy primary emissions and high chance of secondary pollutant productions and accumulations. The air quality in FGD generally has a significant seasonal cycle which is influenced by the East Asian Monsoon and modulated by ENSO. Different cities have different prominent air quality issues and there are special multi-scale characteristics in PM2.5 at FS, O-3 at DG, and PM(2.5-10 )at DG. The inter-city differences of multi-scale air quality variations in FGD could be attributed to both sources and meteorology. For example, DG has extremely high O-3 (especially in 2015) and PM2.5/PM10 but relatively low PM, and PM2.5-10 at DG has strong 2-3 days' oscillation but weak seasonal oscillation. The special air quality characteristics at DG might be attributed to combined effects of the different ventilation and dilution consequences of the sea-land breeze to different air quality components which have different three-dimensional source distributions. Through a combined multi-scale lag correlation analysis of air quality, some prior air quality components (with different leading time on different scales) are identified as potential indicators for statistic air quality prediction.