First data from the POLDER French instrument onboard the ADEOS Japanese satellite

On August 17, 1996, the Japanese NASDA H-II rocket has successfully launched the Japanese Earth observation satellite ADEOS. The orbit configuration operations of the satellite have been achieved nominally and ended on September 8. The ADEOS satellite has a three-year life duration.

 In the framework of a NASDA-CNES cooperation agreement, the French instrument POLDER onboard ADEOS represents the first significant cooperation between France and Japan for the observation of the Earth environment from space.

 Imagined by LERTS Toulouse, CNES and LOA Lille, and developed by CNES in collaboration with French CNRS (LOA, LERTS/CESBIO Toulouse, LPCM Villefranche, LMD Palaiseau, etc.) and CEA (LMCE Saclay) laboratories involved in environmental research, POLDER (Polarization and Directionality of the Earth's Reflectances) collects wide field-of-view (2400 km x 1800 km) and moderate resolution (6 km x 7 km) images in 8 spectral bands of the visible and near-infrared spectrum. It is the first space instrument able to measure the polarized light thanks to an " optical grid " (or polarizer) located in its viewing system.

 The POLDER instrument concept presents a double originality. It allows the observation of a given site:
- with several spectral bands and polarization conditions thanks to a rotating wheel carrying spectral filters and polarizers,
- over various viewing geometries (13 to 14 configurations along the same orbit) thanks to its wide field-of-view and its almost daily revisit capabilities.

 The measurements collected by POLDER will allow: (1) to map at global scale the type and concentration of tropospheric aerosols, (2) to complement and improve the Earth radiation budget (ERB) estimates derived from classical instruments, (3) to determine the cloud properties (phase and top altitude) and their impact on ERB, (4) to assess, under clear sky conditions, the integrated water vapour content of the atmosphere, especially over land surfaces, for the global study of water cycle, (5) to determine the phytoplankton concentration of the oceans and to estimate the marine primary production for the study of the global carbon cycle, and (6) to map the land cover and to determine the surface parameters driving the land primary production and the heat and mass transfers at the land-atmosphere interface.
 

A second model of the POLDER instrument will be launched onboard ADEOS-2, which will follow ADEOS-1 in 1999. Due to the high data rate of POLDER (882 kb/s each half-orbit), the ground segment represents an essential element of the POLDER system. Developed by CNES since 1993, it is now operational to process, archive and disseminate the large amount of collected data. The processing algorithms have been specified by LOA, LMCE, CESBIO and LPCM, and developed in collaboration between CNES and CEA..

 

This view is the first image of Europe and Mediterranean acquired by the POLDER instrument on ADEOS, on September 16, 1996.  More than 15,000 images of this type are acquired each day by POLDER, allowing a daily coverage of the Earth.