A mission for TRopospheric composition and Air Quality (TRAQ)

Abstract

TRAQ (Tropospheric composition and Air Quality) was recently selected for a pre-phase A study in ESA's 2005 EOEP call. TRAQ is a mission focused on understanding the tropospheric system for air quality, sources and sinks, and climate change. The science themes of TRAQ are: How fast is air quality changing on a global and regional scale ? What is the strength and distribution of the sources and sinks of trace gases and aerosols influencing air quality ? What is the role of tropospheric composition in global change ? TRAQ aims at following tropospheric pollution during the day, while at the same time providing information on long-rang transport of pollutants, and a global survey of climate constituents and sources and sinks of tropospheric pollutants. To be able to obtain the time-resolution and daily global coverage needed to answer the three general science questions, TRAQ will fly in an inclined LEO orbit, obtaining measurements up to 4 to 5 times a day over mid-latitudes and global coverage except for the poles. To provide a full suite of tropospheric measurements, containing most key-tropospheric trace gases for pollution and climate change, a set of 4 instruments were selected: an UV/VIS/NIR/SWIR instrument TROPOMI, which is a follow-on instrument to OMI; a FTIR instrument SIFTI; a cloud detector CLIM and an instrument called OCAPI resembling POLDER, with an extension of the spectral range up to 2.2 μm, for pollution aerosol detection. The TROPOMI instrument will measure many tropospheric trace gases, including nitrogen dioxide, HCHO and ozone. The SIFTI instrument will focus on the determination of vertical profiles of ozone and CO in the troposphere (day and night). CO and CH4 tropospheric column measurements including the boundary layer will be achieved by either the SIFTI or the TROPOMI instrument. By combining SIFTI with TROPOMI measurements tropospheric ozone detection can be improved over existing detection techniques. The CLIM imager will provide sub-pixel information on clouds and will be used by SIFTI to detect cloud-free pixels or to correct partially cloudy radiances. OCAPI will provide aerosol optical thickness, aerosol types and size distribution. In the presentation an overview of the mission will be presented focused on the science questions. A simulation of the orbit will be shown.