FAQs - Observations

1. What is the WMO vision for the evolution of its observing systems?

The future Global Observing System will play a central role within the WMO Integrated Global Observing System (WIGOS). This evolved integrated observing system will be a comprehensive “system of systems” interfaced with WMO co-sponsored and other non-WMO observing systems, making major contributions to the Global Earth Observation System of Systems (GEOSS). It will be delivered through enhanced involvement of WMO Members, Regions and Technical Commissions.

The space-based component will rely on enhanced collaboration through partnerships such as the Coordination Group for Meteorological Satellites (CGMS) and the Committee on Earth Observation Satellites (CEOS). Portions of the surface and space-based sub-systems will rely on WMO partner organizations: the Global Terrestrial Observing System (GTOS), the Global Ocean Observing System (GOOS), the Global Climate Observing System (GCOS), and others.

2. How do WMO members decide on the evolution of the global observing systems?

The evolution of the global observing systems is achieved through the Rolling Review of Requirements (RRR) – see Question/Answer “What is the Rolling Review of Requirements (RRR)?” below

3. What is the Rolling Review of Requirements (RRR)?

Through the Rolling Review of Requirements process experts study observational requirements in key WMO application areas (for example, global numerical weather prediction, seasonal to interannual climate forecasting, aeronautical meteorology,  etc.), look at the current observing systems capabilities (both space-based, and surface-based), conduct a critical review (including impact studies in some cases), identify the gaps, and produceStatements of Guidance for each of the application areas. The statements of guidance are then reviewed to produce the Implementation Plan for the Evolution of global observing systems (EGOS-IP). More information on the RRR can be found here.

4. Where are identified observational gaps documented?

After looking at the observational requirements, and the performances of space-based and surface-based observing systems, experts in each WMO application area conduct a critical review, and document the identified gaps in Statements of Guidance for those application areas. The Statements of Guidance can be found here.

Related Information



Currently, well over 10 000 manned and automatic surface weather stations, 1 000 upper-air stations, 7 000 ships, 100 moored and 1 000 drifting buoys, hundreds of weather radars and 3 000 specially equipped commercial aircraft measure key parameters of the atmosphere, land and ocean surface every day. Add to these some 16 meteorological and 50 research satellites to get an idea of the size of the global network for meteorological, hydrological and other geophysical observations. Once collected, observations are quality-controlled, based on technical standards defined by the WMO Instruments and Methods of Observation Programme (IMOP), then made freely available to every country in the world through the WMO Information System (WIS). Read more...