The Tibetan Plateau, also known in China as the Qinghai-Tibet Plateau, has a large influence on atmospheric circulation, hydrological cycle and climate in East Asia as well as the Northern Hemisphere. The plateau, sometimes called "the Roof of the World" or "the Third Pole", covers a huge area located in 73-105 E longitude and 26-40 N latitude, with mean surface elevation of 4000-5000 m above sea level. It has long been considered as one of the remote regions in the Eurasian continent that are relatively less influenced by pollution from human activities. While natural processes that control the temporal and spatial variations of atmospheric composition over the Tibetan Plateau are still inadequately understood, the influence of long-range transport of pollutants from surrounding areas, e.g. South and Southeast Asia, and farther regions on the background atmosphere of the Tibetan Plateau and associated climate impacts have become a scientific issue to be intensively addressed.

Long-term measurements of trace gases, aerosols and radiation have been performed at several remote sites in the Tibetan Plateau region, including e.g. the Waliguan Global Baseline Station and the Shangri-la Regional Background Station (both operated by China Meteorological Administration) and the Nam-Co Comprehensive Observation and Research Station (operated by Institute of Tibetan Plateau Research, Chinese Academy of Sciences). Intensive field campaigns were carried out based on these stations and some other sites of the region during different periods to investigate the levels and variation controlling factors of atmospheric ozone and aerosols over the plateau. Observations include in-situ measurements of ozone and related trace species, in-situ and sampling measurements of aerosol physical properties and chemical composition, sounding of ozone and water vapor, lidar measurements of aerosols, and ground-based remote sensing of selected trace gases, etc. Models are also used to compare with measurement results and interpret data. The purpose of this issue is to expand our understanding of physic-chemical and transport processes that largely influence atmospheric ozone and aerosols as well as radiation over the Tibetan Plateau.