Abstract:
The spatial representativeness (SR) of aerosol mass concentration observations collected at regional background stations in central and eastern China is assessed using the PM
2.5 product from 2010 to 2021, which is extracted from a series of high-resolution and high-quality datasets of ground-level air pollutants over China. The quality and reliability of the dataset are evaluated using observations at the background stations. Specifically, the SR of PM
2.5 at Jinsha (JSA), Lin'an (LAN), Shangdianzi (SDZ) and Longfengshan (LFS) regional background stations in central and eastern China are assessed. The Concentration Similarity Function (CSF) is applied to calculate the average, the intersection/common and the persistence indexes of the SR area at the four stations and the 12-year study period is divided into three continuous stages (2010—2013, 2014—2017, 2018—2021). Main conclusions are as follows. (1) With the mass concentration relative difference threshold 20%, LFS station has the largest average SR area of 22378 km
2, followed by JSA (14490 km
2), and LAN (9841 km
2) and SDZ (7998 km
2) using daily average PM
2.5 product. As for the intersection/common SR area, LFS station has the largest area (18378 km
2), followed by JSA (11915 km
2), while SDZ station (5687 km
2) and LAN (5476 km
2) have relatively small areas. The persistence index of the SR area at JSA and LFS is larger than that at LAN and SDZ. The SR area during 2018—2021 is larger than that during 2014—2017 at the four regional background stations. (2) For the average (intersection/common ) area to satisfy the SR area for the air quality regional background stations specified by the Ministry of Ecology and Environment, the People's Republic of China (i.e. with the radius of 100 km), mass concentration relative difference threshold at the four stations should be ≥40% adopting the daily PM
2.5 product. (3) The average, the intersection/common, and the persistence indexes of the SR area assessed adopting annual average PM
2.5 mass concentrations are all larger or better than those assessed adopting daily average PM
2.5 mass concentrations.