ceos   eesa
The Changing Earth: Environmental Trends Since Rio
Earth Observations – Informing the Conventions
Future Challenges
What is CEOS?

CEOS is the Committee on Earth Observation Satellites, created in 1984 in response to a recommendation from a Panel of Experts on Remote Sensing from Space, under the aegis of the G7 Economic Summit of Industrialised Nations Working Group on Growth, Technology and Employment.

CEOS was established to provide coordination of the Earth observations being provided by satellite missions, recognising that no single programme, agency or nation can hope to satisfy all of the observational requirements that are necessary for improved understanding of the Earth System. Since its establishment, CEOS has provided a broad framework for international coordination on spaceborne Earth observation missions.

What Does CEOS Contribute?

CEOS strives to facilitate the necessary harmonisation and achieve maximum cost-effectiveness for the overall set of space-based observation programmes of member countries and agencies.

CEOS has established three primary objectives in pursuing this goal:

− to optimise benefits of spaceborne Earth observations through cooperation of its members in mission planning and in development of compatible data products, formats, services, applications and policies;

− to serve as a focal point for international coordination of space-related Earth observation activities;

− to exchange policy and technical information to encourage complementarity and compatibility of observation and data exchange systems.

The work of CEOS spans the full range of activities required for proper international coordination of Earth observation programmes and maximum utilisation of their data. It ranges from the development of detailed technical standards for data product exchange, through to the establishment of high-level inter-agency agreements on common data principles for different application areas, such as global climate change and environmental monitoring.

Who Participates in CEOS?

CEOS membership comprises most of the
world’s civil agencies responsible for Earth observation satellite programmes – 31 space agency Members as of 2014. CEOS also has 24 Associates, comprising:

− international or national governmental organisations that are developing Earth-observing satellite programmes or significant supporting ground facility programmes;

− other satellite coordination groups and scientific or governmental bodies that are international in nature and currently have a significant programmatic activity that supports CEOS objectives.

− The full list of Members and Associates is shown in the tables below.


CEOS web site.

The chart shows that participation in CEOS has grown significantly since the Rio Summit in 1992, with representation of national space agencies or space offices more than doubling to a total of 33 organisations across the CEOS Members and Associates. Many more European countries are represented under the regional umbrellas provided by the European Space Agency, with 26 Member or Cooperating States and EUMETSAT, with 31 Member or Cooperating States. Every major international civil Earth observation programme is actively represented in CEOS, indicative of the recognition that CEOS is the key forum for practical coordination on common challenges being addressed by national Earth observation satellite programmes.

How Does CEOS Operate?

CEOS Principals meet annually in a Plenary session to determine policy, review progress on the projects and activities being undertaken, and set the agenda of activities for the upcoming year. The Chair of CEOS rotates at the annual Plenary.

The work of CEOS is conducted within its various working groups and the Strategic Implementation Team (SIT). Coordination throughout the year is maintained through a permanent Secretariat maintained by ESA jointly with EUMETSAT, NASA jointly with NOAA of the USA, and MEXT jointly with JAXA of Japan.

CEOS Activities and Achievements

The establishment GEO via a series of three ministerial-level summits from 2003 to 2005 provided a new focus and impetus for CEOS efforts. GEO includes 89 member countries, the European Commission and 67 participating organisations – including CEOS – working together to establish a Global Earth Observation System of Systems over a 10-year period.

The GEO vision for GEOSS is to realise a future in which decisions and actions for the benefit of humankind are informed via coordinated, comprehensive and sustained Earth observation and information. The 20+ years invested by CEOS agencies towards these objectives have resulted in recognition of CEOS as the primary worldwide forum for coordination of space-based Earth observations. As such, CEOS is tasked to lead coordination of the space observations required by the GEOSS.

The main mechanisms that CEOS employs to implement this role are:

− the CEOS Virtual Constellations;

− the CEOS Working Groups;

− the CEOS Implementation Plan;

− the Space Data Coordination Group.

Each of these is discussed in turn below.

CEOS Virtual Constellations

The CEOS Virtual Constellations provide a new mechanism for better coordination of Earth-observing satellite programmes across borders, allowing valuable contributions from a wide range of parties to build and sustain truly global observing systems in support of one or more key information needs of society. The Virtual Constellations concept involves multiple satellites working in harmony as part of GEOSS to augment coverage, enhance system compatibility and increase data availability. Such an arrangement encourages international cooperation among space agencies while stimulating them to develop a coordinated response to space-based observation needs. It also fosters improved data management and distribution worldwide.
  Seven virtual constellations are currently in progress by CEOS space agencies, in consultation with their respective user communities – each with a major outcome in support of societal information needs:

− The Precipitation Constellation, which aims to strengthen international cooperation of space-based observations of precipitation, including realisation of the Global Precipitation Measurement mission;

− The Land Surface Imaging Constellation, designed to ensure continuity and compatibility of planned land remote sensing systems, and in support of global forest and agricultural monitoring capabilities;

− The Atmospheric Composition Constellation, which will address many of the climate community’s needs for atmospheric observations;

− The Ocean Surface Topography Constellation, designed to ensure continuity of sea-level measurements in accordance with GCOS requirements;

− The Ocean Surface Vector Winds Constellation, emphasising continuity of sea-surface wind measurements for operational user communities;

− The Ocean Colour Radiometry Constellation, providing coordination and continuity in a specialised class of instruments aimed at ocean colour and their importance in global carbon and climate studies;

− The Sea Surface Temperature Constellation, focusing on continuity of sea-surface temperature (SST) measurements for applications in short, medium and decadal time scales in the most cost effective and efficient manner, and coordination on SST Essential Climate Variable dataset development.

Each of these is designed to make key observations for GEOSS and maintain continuity of observations, identifying and addressing potential gaps and overlaps. Part of the process is to identify organisational responsibilities clearly for ensuring the necessary continuity. Further details of selected CEOS Constellations are provided in the Case Studies in Part II of this document.

The CEOS Systems Engineering Office (SEO) was established to facilitate the development of CEOS Constellation planning. SEO provides systems engineering leadership, a framework for coherent architecture plans, and decision support tools for trade-off studies and the assessment of execution options.

Earth observation heads of space agencies from around the globe meet annually at the CEOS Plenary.


The Strategic Implementation Team of CEOS is where heads of space agencies or Earth observation programmes meet to make the decisions required to harmonise their observing programme plans. SIT plays a central role in coordination of existing and future missions of CEOS agencies to support GEO in its realisation of the GEOSS space segment.

The Chair of SIT has a two-year term, with a nominated deputy ready to take over. This provides a level of continuity that has resulted in the Chair of SIT being appointed as the primary interface between CEOS and GEO.

SIT has never had a formal membership. Meetings are open to any CEOS agency that is willing and ready to contribute to one or more of the activities being discussed by SIT, such as the Virtual Constellations projects or particular GEOSS space segment implementation tasks.

CEOS Working Groups

CEOS also uses four Working Groups to support implementation of its activities:

− Working Group on Calibration and Validation (WGCV): with activities on calibration and validation of Earth observations for the benefit of CEOS members and the international user community;

− Working Group on Information Systems and Services (WGISS): focused on interoperability and interconnectivity of information systems and services related to the capture, archiving and exploitation of Earth observation data;

− Working Group on Capacity Building and Data Democracy (WGCapD): facilitating activities that support effective use of Earth observation data, and the advancement and sustainability of satellite Earth observations by empowering users through free access to these resources;

− Working Group on Climate (WGClimate): established in 2010 with the mandate of facilitating the implementation and exploitation of Essential Climate Variable datasets through coordination of the existing and substantial activities being undertaken by CEOS agencies.

More information is provided in Annex A.

CEOS newsletter.

  The CEOS Implementation Plan

The first version of the CEOS Implementation Plan, prepared by the Strategic Implementation Team, was published and endorsed in 2007. It is the mechanism by which CEOS now prioritises, manages and monitors its various tasks in support of the development of the space-based observations for GEOSS. The CEOS Implementation Plan represents a move to a business-like and target-oriented agenda for CEOS as it responds to its responsibilities in support of the GEOSS.

As part of the adoption of the Implementation Plan in 2007, CEOS agencies agreed to establish expert teams for each of the nine ‘Societal Benefit Areas’ of GEOSS, each with the responsibility of progressing and reporting on activities in support of the various GEOSS targets. Oversight of the entire activity is undertaken by the Chair of the CEOS Strategic Implementation Team, with support from the CEOS Executive Officer (CEO). The CEO and SIT Chair have been working closely with the GEO Secretariat in order to prioritise the many actions required for CEOS in support of the GEOSS space segment.

The CEOS Implementation Plan is updated annually to demonstrate how well the coordination processes are working to achieve the required outcomes.

Space Data Coordination Group

In recognition of the increasing demands anticipated of CEOS and its agencies in support of data coordination and delivery, CEOS in 2012 established a Space Data Coordination Group (SDCG). The first priority for SDCG is to plan how cooperating agencies can schedule their available satellite systems in support of the annual, global coverage requirements arising from GEO’s Global Forest Observations Initiative. This is a significant undertaking by the world’s space agencies through CEOS and will require a substantial and sustained commitment to data supply.

Similar requirements are emerging in support of the GEO Global Agricultural Monitoring initiative, in support of the G20 Action Plan on Food Price Volatility and Agriculture. This aims to develop an Agricultural Market Information System in order to encourage major players on the agri-food markets to share data, improve existing information systems, promote greater shared understanding of food price developments and further policy dialogue and cooperation. Significant areas of the planet will have to be imaged several times a year in support of these ambitions, and CEOS is best placed to support the international coordination required around data acquisition and supply.

The processes and tools being developed within SDCG for the global forest observations will have value in support of the agricultural monitoring goals, and other emerging priorities.

Further information on these activities is the subject of several of the case studies in Part II.

More Information

Further information on the structure, activities and achievements of CEOS is provided in Annex A this document.

CEOS brochure.


Further Information

Earth Observation Handbook:
Missions, Instruments and Measurements (MIM) Database: