| Areas of particular focus | | |
Global Terrestrial Network for Glaciers (GTN-G) | Land Resources- Sustainable Development- Global Sea Level Rise- Water Resources- | Glaciers (Glacier Area, Glacier Elevation Change, Glacier Mass Change), Snow Cover, Ice Sheets and Ice Shelves, (Sea Level) | On global scale; regularly updated information on glacier distribution and changes; fluctuations database at WGMS with >3,500 glaciers since 19th century; inventory database at NSIDC with> 100,000 glaciers from mid 20th and early 21st centuries |
Global Terrestrial Network for Hydrology (GTN-H) | | Precipitation, Water Vapour, River Discharge, Ground Water, Anthropogenic Water Use, Lakes, Soil Moisture | On global and regional scale (national monitoring programmes, science programmes); data from 1900 onwards (single variables, discontinuous) |
Global Terrestrial Network for Lake (GTN-L) | | Lakes ( Lake Water Level, Lake Water Extent, Lake Surface Water Temperature, Lake Ice Cover, Lake Ice Thickness, Lake Water-Leaving Reflectance) | Mainly on regional basis (>600 water level reference stations); monthly and annual data input |
Global Terrestrial Network for Permafrost (GTN-P) | | Permafrost (Permafrost Temperature, Active Layer Thickness, Rock Glacier Velocity) | Mainly on regional and national basis (80-site network under IPA’s Circumpolar Active Layer Monitoring (CALM); inventory and metadata for >200 boreholes of varying depths) |
Global Terrestrial Network for Rivers (GTN-R) | | River Discharge, River Water Level | Mainly on regional basis (> 300 river discharge reference stations); daily or monthly data input; highly dependent on data provided by National Meteorological and Hydrological Services (NMHS) |