GCOS Surface Network (GSN)

A weather station on a grassy hilltop with mountains in the background under a cloudy sky.

To serve specifically the needs of global climate applications, two networks of observing stations have been established as Global Climate Observing System (GCOS) Baseline Networks, mainly based on existing GOS networks. These are:

the GCOS Surface Network (GSN) (1025 stations as of 01/11/2024)
the GCOS Upper-Air Network (GUAN) (178 stations as of 01/11/2024)

These networks form a minimum configuration required for global applications. Regional climatic needs can be much more extensive, and it is anticipated that such needs will be served by more dense networks on a regional basis, possibly with more extensive requirements for observing programmes and specifications.

The GSN is a baseline network comprising a subset of about 1000 stations, chosen mainly to give a fairly uniform spatial coverage from places where there is a good length and quality of data record. The mandatory parameters measured by a GSN station are temperature and precipitation.

The detailed requirements of the GSN are documented in the GCOS publication 144 - ‘GUIDE TO THE GCOS SURFACE NETWORK (GSN) AND GCOS UPPER-AIR NETWORK (GUAN)’, and is accessible from the WMO e-library.

Near Real Time data, and monitoring products, are available at the GSN Monitoring Centre (GSNMC), which is managed by Deutscher Wetterdienst (DWD). Additional monitoring products are available on the WMO Data Quality Monitoring System (WDQMS).

The National Centers for Environmental Information (NCEI) provide the long-term climate archive of global surface data, and provide an annual summary of the GSN performance statistics. For more information: 2023 GSN availability statistics.