Developments in the 'validation' of satellite sensor products for the study of the land surface

Increased availability of global satellite sensor data is resulting in an increase in satellite sensor products for global change research and environmental monitoring. The ensuing research and policy directives that will utilize these satellite products puts a high priority on providing statements of their accuracy. The process of quantifying the accuracy of these geophysical products is herein termed 'validation'. This Letter provides examples of international land product 'validation' research and describes a new international forum for coordination within the Committee on Earth Observation Satellites (CEOS) Calibration and Validation Working Group (CVWG).