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 August 2020, GRUAN comprises of 30 sites, 12 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



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…


AMT paper Hoshino et al. 2022 in review

For the paper GRUAN data products from Meisei iMS-100 and Vaisala RS92 were compared with 57 dual sounding data.


ICM-13 meeting report published

The report of the GRUAN ICM-13 meeting is available for download.


AMT paper von Rohden et al. 2022 published

The paper describes the radiation correction for the RS41 that was developed using the custom-built laboratory test facility SISTER at the Lead…


AMT paper Ingleby et al. 2022 published

The study evaluates the quality of descent data from operational radiosoundings - mainly for Vaisala RS41 - and compares them with ascent profiles…


AMT paper Lee et al. 2021 in review

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


ICM-13: presentations and documents available

The 13th GRUAN annual Implementation and Coordination Meeting, ICM-13, took place 15-19 November 2021 as virtual meeting. All presentations and…