In November 2011, there were 111 CEOS agency EO satellites operating and providing important data about the Earth and its environment, helping us to develop our understanding of the basic Earth System and human influences on it. These data cover measurements of a very wide range of geophysical parameters, spanning the whole spectrum of the environment – atmosphere, land, oceans, ice and snow. This section considers some of the key observations contributed by EO satellites, as indicated in the table.

This list is not exhaustive, but it does include many key measurements of interest to the main user groups of Earth observation satellite data, and describes a significant part of the capability of current and planned instruments – including those related to the Essential Climate Variables which are largely measured by satellite.

This section identifies the satellite instruments which primarily contribute data for any particular measurement from the list shown and indicates the plans for future provision of that measurement over the next 15 years. Measurement continuity is a key requirement, particularly for climate applications, in order to detect and quantify long term trends. This section identifies the prospects for achieving that continuity, given the programmes and plans that exist in 2010 – whether it may be provided by a single series of satellites dedicated to a particular measurement, or whether users of that measurement must look to various satellite missions planned by different agencies worldwide to satisfy their information requirements.

The need for this continuity and the necessity to ensure that the measurements obtained by different agencies from different countries can be inter-compared and calibrated to meet the most demanding requirements (typically for climate applications), requires a significant degree of coordination in mission planning and data provision. Harmonisation and maximum cost-effectiveness for the total set of space-based observation programmes is the objective of CEOS