Atmosphere
This proposal addresses different aspects related to the air quality (AQ) over China: aerosols, trace gases and their interaction through different processes, including effects of radiation and meteorological, geographical and topographical influences. Detailed in situ measurements are combined with ground-based and satellite remote sensing which together provide complimentary information on the contributions from different sources and processes affecting AQ, with scales varying from the whole of China to local studies and from the surface to the top of the boundary layer and above. Different species contributing to air quality will be studied, i.e. aerosols, in AQ studies often represented as PM2.5 (mass of dry particles with in situ diameter smaller than 2.5 µm), trace gases such as NO2, NH3, Volatile Organic Compounds (VOCs) and O3. The primary source of information in these studies is the use of a variety of satellite-based instruments providing data on atmospheric composition using different techniques. Concentrations of atmospheric components are either retrieved by the EMPAC consortium or downloaded from public data services such as COPERNICUS. They are validated using reference data sets and evaluated by comparison with other satellite data over areas where no reference data are available. For the interpretation of satellite data and their use to AQ studies, a wide variety of data from other types of observations is used, providing complementary information on the species measured from satellites, as well as meteorological information and large-scale phenomena. In particular this proposal focuses on the relationship between satellite-based column-integrated properties and near-surface concentrations important for AQ which would allow for the use of satellites to provide AQ information on large spatial scales. To understand the satellite/surface relationships, detailed process studies will be undertaken, using ground/based in situ measurements, instrumented towers and drones, as well as remote sensing using lidar and Max-DOAS. A unique source of information on the vertical variation of NO2, O3, PM2.5 and BC is obtained from the use of an instrumented drone. The proposal is structured along three related topics: Aerosols, Trace Gases and biosphere/atmosphere interactions.
