Vertical distribution of ozone in the planetary boundary layer at the Ming Tombs, Beijing

Surface ozone (O3) and vertical O3 distribution in the planetary boundary layer (PBL) at the Ming Tombs (40°17′15″N, 116°12′51″E), Beijing during September 7―12, 2001 were measured by ground based measurements and an in-situ tethersonde system. The results indicated that O3 concentration measured at surface level agreed well with that measured by tethersonde system in daytime when active thermal mixing was dominated. Ozone showed the lowest concentration before the sunrise and then gradually increased in the morning and reached the maximum in the afternoon 14:00―17:00 (lst). After sunset, O3 gradually decreased and resulted in low value below 200―300 m due to surface loss processes and chemical destruction in stable boundary layer characterized by temperature inversions. High O3 was observed whenever there was pollutants transport from the metropolitan areas of Beijing. Our analysis suggested the complex terrain of the Ming Tombs region caused pollutants transported from Beijing to accumulate in the PBL, and resulted in severe O3 pollution, with a maximum over 160×10-9, when the synoptic conditions was favorable for photochemical O3 production.