POLDER IN FLIGHT FIRST RESULTS

摘要

This paper presents the first in-flight results of the new Polarization and Directionality of the v Earth's Reflectance (POLDER) instrument. The POLDER sensor has been developed by the Centre National d'Etudes Spatiales, the French space agency ; it is part of the payload of the Advanced Earth Observation Satellite (ADEOS) developed by NASDA and launched in August 1996. POLDER on ADEOS is the first French-Japanese space co-operation.The POLDER sensor is designed to collect global and repetitive observations of the solar radiation reflected by the Earth-Atmosphere system for ciimate research ; this includes the aerosol cycling, the aerosol-cloud-radiation interactions, the Earth radiation budget, the ocean primary production and the continental biosphere dynamics.The sensor is a wide field-of-view (2400 Km swath), moderate resolution (6×7 Km~2 at nadir) multi-spectral imaging radiometer / polarimeter. The instrument concept is based on a telecentric optics, a rotating wheel carrying 15 spectral filters and polarizers, and on a bidimensionnal CCD detector array ; owing to this concept, POLDER has the unique ability to measure polarized reflectances, to observe target reflectances from up to 14 directions during a single satellite pass and from more directions by multi-pass combination.The multi-disciplinary scientific objectives of POLDER lead to severe radiometric and geometrical requirements, as well as a very accurate calibration of the sensor ; these requirements are achieved through a stable instrument design and an original ground processing ; the first images presented show the originality of polarized images after processing and also the contribution of multi-directionnal viewing.A spare model of the POLDER instrument has been manufactured ; it will be flown on the ADEOS II satellite, the launch of which is planned 3 years after ADEOS launch, in 1999.