The Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) is an international reference observing network, designed to fill an important gap in the current global observing system. GRUAN measurements will provide long-term, high-quality climate data records from the surface, through the troposphere, and into the stratosphere. These will be used to determine trends, constrain and calibrate data from more spatially‐comprehensive observing systems (including satellites and current radiosonde networks), and provide appropriate data for studying atmospheric processes. GRUAN is envisaged as a global network of eventually 30-40 sites that, to the extent possible, builds on existing observational networks and capabilities.
The GCOS/WCRP Atmospheric Observation Panel for Climate (AOPC ) Working Group on GRUAN (WG-GRUAN), formerly named Working Group on Atmospheric Reference Observations (WG-ARO), was established in 2006 in recognition of the importance of initiating reference-quality observations of vertical profiles of essential climate variables from the surface into the stratosphere to enhance monitoring and understanding of climate variability and change.
The GRUAN Lead Centre is to be responsible for the monitoring of the Global Climate Observing System (GCOS) Reference Upper Air Network (GRUAN), including development of GCOS needs for station operation, coordination among stations, and ensuring archival and dissemination of GRUAN data.
The GCOS/WCRP Atmospheric Observation Panel for Climate (AOPC) Working Group on GCOS Reference Upper Air Network (WG-GRUAN) was established in 2006 in recognition of the importance of initiating reference-quality observations of atmospheric column properties, in particular temperature and water vapour, from the surface into the stratosphere to enhance the monitoring and understanding of climate variability and change. At the second GRUAN Implementation and Coordination Meeting (ICM) held in Payerne, Switzerland in March 2010 the Working Group, Lead Centre and initial sites agreed to the instigation of a number of task teams.
GRUAN is envisaged as a network of 30-40 high-quality, long-term, upper-air observing sites that are built on, but not confined to, the larger GCOS Upper Air Network.