GCOS Reference Upper-Air Network

The climate reference network

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 RS92 and the Meisei RS-11G radiosonde, GRUAN Data Products (GDP) have been fully implemented and certified. Further GDPs are in certification process or under development.

Latest news



ICM-14: La Réunion

ICM-14 will be organized as a hybrid meeting 28 November - 2 December 2022.


UAII2022 field campaign

The field campaign of UAII2022 was successfully executed between 8 August and 13 September. In this period, more than 80 balloons were launched,…

Document Data product

GRUAN Technical Note 13 published

GRUAN Technical Note 13 (GRUAN-TN-13) published with title "User Guide for the RS41 GRUAN Data Product Version 1 (RS41-GDP.1)"

Document File archive

GRUAN Technical Note 12 published

GRUAN Technical Note 12 (GRUAN-TN-12) published with title "Brief Description of Vaisala DigiCORA® 3 DataBase File Format (DC3DB)"


AMT paper Hoshino et al. 2022 published

The manuscript "Comparison of GRUAN Data Products for Meisei iMS-100 and Vaisala RS92 Radiosondes at Tateno, Japan" by Hoshino et al. has been…


AMT paper Lee et al. 2022 published

The manuscript "Laboratory characterisation and intercomparison sounding test of dual thermistor radiosondes for radiation correction" by Lee et al.…


UAII2022 campaign kick-off

The laboratory measurements in February 2022 marked the official start of the UAII2022 campaign, which is composed of laboratory tests of the…

Document Metadata

GRUAN Report 5 published

GRUAN Report 5 (GRUAN-RP-5) published with title "Cloud observations"


JAMC paper Zhang et al. 2022 published

The manuscript "Characteristics of Temperature and Humidity Inversions Based on High-Resolution Radiosonde Observations at Three Arctic Stations" by…


Atmosphere paper Rosoldi et al. 2022 published

The manuscript "Intercomparison of Vaisala RS92 and RS41 Radiosonde Temperature Sensors under Controlled Laboratory Conditions" has been published on…


MST paper Colombo et al. 2022 published

The manuscript "Quantifying the interpolation uncertainty of radiosonde humidity profiles, Colombo & Fassò" has been published on Measurement Science…