How does the observing system work?

A weather monitoring station with solar panels stands in a vast, snow-covered landscape under a cloudy sky.

WMO’s World Weather Watch was founded in 1963. It is less well known than the other WWW - World Wide Web – but arguably just as important.

Every day, millions of observations are gathered worldwide by thousands of land-based observing stations, ocean buoys, ships, aircraft and satellites as part of the WMO Integrated Global Observing System (WIGOS). The observations and data are shared via the WMO Information System (WIS) and run through the WMO Integrated Processing and Prediction System (WIPPS) that makes the products and services operationally available.

In parallel with this, the Global Atmosphere Watch network monitors levels of greenhouse gases and common pollutants, as well as the state of the Earth’s protective ozone layer.

The Global Climate Observing System provides a longer-term perspective for key climate indicators which reflect the state of the planet.

These are more than just titles and acronyms!

It is thanks to this unrivalled combination of human expertise, technological ingenuity and global collaboration that reliable and timely forecasts are available to billions of people. 

Surface observations – temperature, humidity, pressure, rainfall and wind – from automatic weather stations and from human observers, are simultaneously recorded and transmitted. The network coordinated by WMO includes some 16,300 surface land meteorological stations , of which about 9,000 are in the Global Basic Observing Network.

Twice a day, every day, weather balloons are launched at more than one thousand locations on every continent, including remote Polar and mountain regions, on small islands and city airports. They take measurements of temperature, humidity and wind as they ascend up to 30 kilometres into the atmosphere with the data relayed in real time. After more than an hour, the balloon bursts and the small instrument package descends.

Ocean observations – The "eyes" of its thousands of observing platforms feed weather forecasts, early warnings and climate prediction.

A major contributor to observations is the Argo program, with nearly 4,000 robotic floats which monitor ocean heat, salinity, and circulation patterns. In addition. More than 1,000 Voluntary Observing Ships provide real-time meteorological data, and there is a campaign to increase this to 10,000 ships.

Aircraft observations – Weather forecasts are essential for flight safety and efficiency, and aircraft feed into the observing system that they benefit from. More than 700,000 high-quality observations per day of air temperature and wind speed and direction are made by the global Aircraft Meteorological Data Relay (AMDAR) observing system, which embraces WMO, aviation authorities and 40 commercial airline companies.

Satellites – Earth observation satellite data are the most crucial input for weather forecasting and are operated by more than 90 space agencies or organizations. There are currently in-orbit around 400 earth observation satellites, of which 31 are geostationary (at 32,000 km) and more than 300 polar-orbiting (500-800 km). In addition, there are satellites on other orbits mainly supporting space weather applications.

These satellites provide a continuous, global view of the atmosphere, oceans, land surface and ice. They allow us to track developing storms, measure temperatures, observe sea-level rise and changes in glaciers and sea ice, detect wildfires and dust storms. Without satellites, large parts of the planet – especially the oceans (which cover more than 70% of Earth’s surface) – would remain poorly observed.