The Geostationary Fourier Imaging Spectrometer (GeoFIS) as part of the Geostationary Tropospheric Pollution Explorer (GeoTroPE) mission: objectives and capabilities J.-M. Flaud a, * , J. Orphal a , G. Bergametti b , C. Deniel c , Th. von Clarmann d , F. Friedl-Vallon d , T. Steck d , H. Fischer d , H. Bovensmann e , J.P. Burrows e , M. Carlotti f , M. Ridolfi f , L. Palchetti g a Laboratoire de Photophysique Mol eculaire (LPPM), CNRS UPR3361, B^ at. 350, Centre d’Orsay, 91405 Orsay Cedex, France b Laboratoire Inter-Universitaire des Syst emes Atmosph eriques (LISA), Universit es Paris 7-Paris 12, CNRS UMR7583, 61 av. du G en eral de Gaulle, 94010 Cr eteil Cedex, France c Centre National d’Etudes Spatiales (CNES), Direction des Programmes, 2 Place Maurice Quentin, 75039 Paris Cedex 01, France d Forschungszentrum Karlsruhe, Institut f€ ur Meteorologie und Klimaforschung (IMK), Postfach 3640, 76021 Karlsruhe, Germany e Institut f€ ur Umweltphysik (IUP), Institut f€ ur Fernerkundung, Universit€ at Bremen, Postfach 330440, 28334 Bremen, Germany f Dipartimento di Chimica Fisica e Inorganica, Universit a di Bologna, Viale del Risorgimento, 4, 40136 Bologna, Italy g Istituto di Fisica Applicata ‘‘Nello Carrara’’(IFAC), Consiglio Nazionale delle Ricerche, 50127 Firenze, Italy Received 1 December 2002; received in revised form 26 March 2003; accepted 18 July 2003 Abstract The Geostationary Fourier Imaging Spectrometer (GeoFIS) is proposed as part of the European Geostationary Tropospheric Pollution Explorer (GeoTroPE) mission. For this mission, two instruments are considered: one covering the thermal infrared region (GeoFIS) and one covering the ultraviolet–visible and near-infrared regions (GeoSCIA). The geostationary orbit (GEO) provides indeed a unique opportunity of monitoring tropospheric pollution and photochemistry on the regional and continental scales. In this paper, the scientific goals and requirements of GeoFIS are described. Ó 2004 COSPAR. Published by Elsevier Ltd. All rights reserved. Keywords: GeoTROPE mission; GeoFIS; Thermal infrared; Geostationary orbit; Tropospheric pollution 1. Introduction – Scientific objectives One of the major challenges facing atmospheric sci- ences is to assess, understand and quantify the impact of natural and anthropogenic pollution on air quality on Earth at a local, regional and continental scale. In the troposphere the characteristic time of chemical pro- cesses, of source strengths and of the dynamics induce important short term, i.e., sub-hourly, variations, and significant horizontal and vertical variability of constit- uents and geophysical parameters (e.g., Scheel et al., 1997; Menut et al., 2000; Bey et al., 2001; Elbern and Schmidt, 2001). To study tropospheric composition and processes it is therefore required to link diurnal with seasonal and annual timescales, as well as local with regional and continental spatial scales, by performing sub-hourly measurements at appropriate horizontal and vertical resolution (WMO-GAW, 2000). Tropospheric observations from low-Earth orbit (LEO) platforms have already demonstrated the potential of detecting constituents relevant for air quality but they are limited by the daily revisit time and local cloud cover statistics (Burrows et al., 1999; Bovensmann et al., 1999; Beer et al., 2001; Bowman et al., 2002). The net result is that from LEO the troposphere is significantly under- sampled. In fact, the Geostationary Orbit (GEO) offers * Corresponding author. Tel.: +33-1-69-15-7606; fax: +33-1-69-15- 7731. E-mail address: jean-marie.flaud@ppm.u-psud.fr (J.-M. Flaud). 0273-1177/$30 Ó 2004 COSPAR. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.asr.2003.07.072 www.elsevier.com/locate/asr Advances in Space Research 34 (2004) 688–693