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This Algorithm Theoretical Basis Document (ATBD) describes an algorithm used to retrieve information on the nature and properties of vegetated terrestrial surfaces from an analysis of time series of surface product values. Time series of surface products derived from the interpretation of satellite data operating in the solar domain suffer sporadically from a lack of information due to, for instance, the presence of clouds. A time composite procedure is therefore needed in order to enhance the geographical coverage by simply accumulating for any desired location on the Earth, the information which is available during the composite period. Monitoring the state and evolution of the vegetation cover is traditionally done with the Normalised Difference Vegetation Index (NVDI), but this index is quite sensitive to perturbing factors such as changes in soil colour and atmospheric effects. The time composite algorithm proposed here follows a simple strategy that can be used for various surface products such as the daily surface Albedo and, more specifically, the instantaneous FAPAR and "rectified" products extracted from data taken by the SeaWiFS, MERIS, VEGETATION and GLI sensors. This document identifies the sources of input data, outlines the physical principles and mathematical background justifying this approach, describes the proposed algorithm, and lists the assumptions and limitations of this technique.

Additional information

Authors: PINTY B ET AL, European Commission, Joint Research Centre, Institute for Environment and Sustainability, Ispra (IT)
Bibliographic Reference: EUR 20150 EN (2001), pp.8. Euro: Free of charge
Availability: Available from European Commission, JRC Knowledge Management Unit, Ispra (IT) Tel: +39 033278 9843 or +39 033278 9864 Fax: +39 033278 9623 E-mail:
Record Number: 200214448 / Last updated on: 2002-02-20
Original language: en
Available languages: en