Seminar

Abstract

The Sentinel-4 and -5 missions, including the Sentinel-5 precursor/TROPOMI mission, will continue data records on atmospheric composition that started with ESA's ENVISAT (SCIAMACHY) and NASA's EOS-Aura (OMI) missions. The Sentinels are of paramount importance for building long-term atmospheric composition data records for climate monitoring purposes. An important application of these data records is protocol monitoring, i.e. observations in support of the Montreal Protocol for the ozone layer, the Kyoto Protocol and possible future agreements concerning climate forcing, as well as observations supporting air quality legislation on national, European and global scale, within the framework of the UN Convention on Long-Range Transboundary Air Pollution (CLRTAP).

The single payload Sentinel 5 precursor mission will be launched end of 2014 and will carry the new TROPOMI instrument. TROPOMI is jointly developed by The Netherlands and ESA. KNMI fulfils the PI role for the TROPOMI instrument, as well as for OMI. The Sentinel-4 mission is a UVN instrument on the geostationary Meteosat Third Generation Sounder mission, to be launched in 2018. The Sentinel-5 mission is a UVNS instrument on the Metop Second Generation missions, to be launched after 2020. This mission will also contain amongst others a TIR sounder and potentially also an aerosol instrument.

The atmospheric Sentinel data are needed to improve our understanding of the physical and chemical processes concerning climate change, air quality, and ozone layer. Improvements in the Earth System modelling combining climate and atmospheric chemistry is for a large part dependent on availability and improvement of long-term atmospheric composition data records in terms of frequency of observation (daily or even diurnal observations), accuracy, spatial resolution, vertical resolution, and global coverage. The data of Sentinels-4 and -5, including the Sentinel-5 Precursor mission, will be used for emission source identification and quantification using inverse modelling techniques. This information will improve the boundary conditions for the climate and air quality models, as well as better constrain current emission monitoring. Currently climate and air quality models use bottom-up estimates (i.e. a calculation of the atmospheric emissions based on certain assumptions) and are thus not based on direct observations of emission sources.

Important are the interactions between air quality and climate forcing, since short-lived trace gases and aerosols play a double role. For example, the necessary measures to improve upon air quality may counteract climate mitigation policies. Strategies need to be sought that take into account the complex chemical feedback mechanisms between air pollutants and climate forcing. Similar complex climate-couplings exist with respect to stratospheric ozone and climate forcing, see for example the climate forcing prevented by the Montreal Protocol and the anticipated interactions between climate change and ozone recovery in the 21^st century.

The presentation will provide information on the Sentinel missions and elaborate on the potential of the Sentinel-4, -5 and -5P/TROPOMI missions for Protocol monitoring and chemistry-climate interaction, using examples based on OMI, SCIAMACHY, Metop and EOS-Aura data.