The Core Service biogeophysical Parameter (CSP) uses the CYCLOPES visible and NIR hemispheric albedo derived from VEGETATION data to elaborate customized product according to the Observatory Natural Carbon (ONC) requirements. ONC needs 0.5° x 0.5° tiled averages (mean and standard deviation values) maps of surface albedo for 8 vegetation classes ("conifer evergreen forest", "deciduous forest", "broadleaf evergreen forest","grassland C3", "grassland C4", "crops C3", "crops C4") (Examples below)

Maps of mean Surface Albedo for the different vegetation types, in June 2003.

The customized albedos presently available have been derived from version 1 of the CYCLOPES products for the years 2002 and 2003. They are provided with an algorithmic documentation and technical documentation (readme).

The surface albedo is also a product of the EWBMS (Energy and Water Balande Monitoring System) database provided by EARS. It is derived from METEOSAT visible (0.3-1.5 µm) images, so its spatial resolution is 5 km sub-satellite. The first step of the methodology consists in calibrating the noon visible METEOSAT image to obtain the daily planetary albedo. The planetary albedo is related to the surface albedo by means of a two-flux radiation transmission model, modified after Kondratyev (1969). In this model the turbidity of the atmosphere is parameterized by the atmospheric optical depth. One pair of corresponding planetary and surface albedo values is required to determine the atmospheric optical depth. A darkest pixel approach is used, which relates the minimum planetary albedo of land pixels occurring in the image to the lowest land surface albedo, usually present over forest. The value of atmospheric optical depth thus obtained is assumed to apply as a first order atmospheric correction to the whole image. Knowing this value, the actual atmospheric correction consists in converting all planetary albedo to surface albedo. In this way, a daily surface albedo map is obtained. Finally, as the daily surface albedo is not expected to change fast, but may be sub-pixel cloud contaminated, a 10-day lowest value surface albedo composite is generated, which is supposed to represent the cloud free situation.

To get the products provided by EARS, it is necessary to make a request at the address ears@ears.nl.