The Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) is an international reference observing network of sites measuring essential climate variables above Earth's surface, designed to fill an important gap in the current global observing system. GRUAN measurements are providing long-term, high-quality climate data records from the surface, through the troposphere, and into the stratosphere. These are being 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.
GRUAN promotional video
This video provides an excellent overview of the goals and principles of GRUAN and its relation to the current challenges in climate research. You can find this and other public outreach material here.
Status of GRUAN sites
GRUAN is envisaged as a global network of eventually 30-40 measurement sites. To the extent possible, it builds on existing observational networks and capabilities. As at November 2022, GRUAN comprises of 31 sites, 14 of which have been GRUAN certified.
Status of data flow
A comprehensive volume of measurement data has been collected by GRUAN since 2008. The archive includes raw data and related meta-data. For the Vaisala RS41 & RS92 and the Meisei iMS-100 & RS-11G radiosondes, GRUAN Data Products (GDP) have been fully implemented and certified. Further GDPs are in certification process or under development.
Latest news

Document
GCOS-253 - GRUAN Implementation Plan 2024-2030 published

Document Data product
RS41 GRUAN Technical Document 8 (GRUAN-TD-8) published

Meeting
ICM-15 mid-March 2024 in Switzerland

Campaign
UAII2022 field campaign

Article
AMT paper Trent et al. 2023 published

Article
RS paper Wee et al. 2022 published

Article
RS paper Zhang et al. 2023 published
Article
Nature article to high-altitude balloons

Article
ACP paper Prange et al. 2023 published

Meeting
ICM-14 meeting report published

Data product