Satellite observations for the geosphere–biosphere programme

This article reviews the role of satellite observations vis-à-vis the requirements of the geosphere–biosphere-programme (GBP). An introductory background on the GBP is followed by an analysis of the accuracy requirements for various important parameters classified as those from atmosphere, land and ocean/cryosphere. Satellite sensors addressing some of the observational requirements are discussed, again parameter/theme-wise. In each case, a mention of the principle or approach to the observation is made, and the expected accuracy compared with the desirable one. It is seen that in most cases, sensors are ready to meet the desired level of accuracy, whereas in some cases, such as ocean salinity, near-surface humidity, etc. even the foreseeable state-of-the-art may not be fully adequate, or may have to undergo tests and validation.