Geostationary Tropospheric Pollution Explorer

Tropospheric pollution monitoring on a regional scale

Executive Summary

of the Proposal submitted in response to ESA's 2nd Call for Proposals for the Earth Explorer Opportunity Missions

prepared by:

  • University of Bremen (D)
  • CNRS - Université Paris-Sud (F)
  • University of Leicester (UK)
  • KNMI (NL)
  • Forschungszentrum KarIsruhe/IMK FZK (D)
  • The GeoTROPE Science Team
  • Astrium (D, UK)
  • OHB-System (D)
  • TPD-TNO (NL)
  • SIRA Ltd. (UK)
  • Lead Investigator:

    Prof. John. P. Burrows,
    Institute of Remote Sensing and Environmental Physics,
    University of Bremen / FB1,
    P.O. Box 33 04 40,
    D - 28334 Bremen, Germany
    Phone:+49-421-218 4548,
    Fax: +49-421-218 4555
    The scientific objective of the GeoTROPE mission is to investigate and assess the importance of anthropogenic activity and natural phenomena on the changing tropospheric composition, linking diurnal with seasonal to annual timescales, and regional with continental to global spatial scales.

    In the troposphere the variability of chemical loss and source strength combined with the dynamics of transport and mixing induce significant and important short term, i.e. sub-hourly, variations and significant horizontal and vertical variability of constituents and geophysical parameters. Observational limitations of low-Earth orbit (LEO) platforms (daily revisit time, local cloud cover) dictate that the troposphere is significantly undersampled. In order to fulfil the scientific objective there is an overriding requirement for sub-hourly measurements, including night-day cycles, at appropriate horizontal and vertical resolution. Measurements from Geostationary Orbit (GEO) offer the only practical approach to the observation of diurnal variation from space with the pertinent horizontal resolution. Maximum vertical resolution from passive remote sounding measurements from GEO is best achieved in nadir viewing geometry by combining the measurements of selected absorptions of targeted constituents in the backscattered solar and the thermal infrared terrestrial radiance.

    The GeoTROPE mission objective addresses specifically two atmospheric research areas: (a) Pollution/Air Quality, (b) Biomass burning. The scientific areas for GeoTROPE are placed within broader overarching issues such as tropospheric O3 level, acidic deposition, natural vs. anthropogenic emissions, chemistry-climate feedbacks, carbon cycle, and treaty verification. The mission objectives will respond directly to theme 4 of ESA's Living Planet Programme, but also contribute to themes 2 and 3. GeoTROPE would form an appropriate element in the implementation of the joint EU/ESA initiative for a European approach to GMES and can be seen as a demonstration mission for new post-MSG operational meteorological services.

    From a quantitative assessment of the scientific requirements the targeted geophysical parameters for GeoTROPE are:

    In order to measure these parameters GeoTROPE comprises two nadir-looking instruments, a UV-VIS-NIR-SWIR spectrometer (GeoSCIA) to be provided by DLR, and a FTIR spectrometer (GeoFIS) to be provided by CNES, mounted on a geostationary platform and utilising geostationary orbit for a focussed tropospheric composition mission. The chosen geographic area will cover the European continent, Africa, middle East and surrounding oceans. The area will be covered every 30 min. - 60 min. with a horizontal sampling of 11.5 x 23 km2 to 23 x 23 km2 (at sub-satellite point), depending on the measurement mode of the instruments. The GeoTROPE measurements and instrumentation are novel and innovative, but based on proven instrumental concepts and on the heritage from successful missions previously flown on LEO platforms.

    The mission concept will be realised by using the instruments mounted on a dedicated spacecraft, based on a commercial telecommunications 3-axis stabilised platform with enhanced attitude and orbit control system to achieve the required pointing stability. Both instruments are operated 24 hours/day (except during S/C eclipse), requiring a dedicated data reception antenna for handling a continous data stream (approx. 50 Mbit/s). For the GeoTROPE mission a standard launch as secondary payload with Ariane V will be utilised. The mission duration is proposed to be 3 years, although the spacecraft and instrumentation will be designed for a mission duration of at least 5 years. As a result of the national contributions of DLR and CNES, the ESA costs for GeoTROPE is within the specified EEOM budget.

    Stefan Noël / Last Change.