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 March 2024, GRUAN comprises of 33 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

Article

AMT paper Jayaweera et al. 2025 published

The manuscript "Solar background radiation temperature calibration of a pure rotational Raman lidar" has been published on Atmospheric Measurement…
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Meeting

Save the date: ICM-16 17-21 November 2025

ICM-16 will be organized Mo-Fr 17-21 November 2025 in Puerto de la Cruz, Tenerife (Spain).

Article

JTECH paper Wang et al. 2025 published

The manuscript "Temperature Fluctuations of Different Vertical Scales in Raw and Processed U.S. High Vertical-Resolution Radiosonde Data" has been…

Article

Atmosphere paper Alraddawi et al. 2025 published

The manuscript "Calibration of Upper Air Water Vapour Profiles Using the IPRAL Raman Lidar and ERA5 Model Results and Comparison to GRUAN Radiosonde…

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EGUsphere paper Fujiwara et al. 2025 in review

The following GRUAN-relevant paper was published at EGUsphere [preprint]: "Justification for high ascent attainment for balloon radiosonde soundings…

Article

AMT paper Sugidachi et al. 2025 published

The manuscript "Development of a Peltier-based chilled-mirror hygrometer, SKYDEW, for tropospheric and lower-stratospheric water vapor measurements"…

Article

PNAS paper Atlas et al. 2025 published

The paper "Turbulence in the tropical stratosphere, equatorial Kelvin waves, and the quasi-biennial oscillation" has been published on Proceedings of…
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Article

IGARSS contribution De Angelis et al. 2024

The contribution "CAL/VAL Preparatory Activities for The EPS-SG MWI and ICI Instruments" has been published on IGARSS 2024.

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AMT paper Meijer et al. 2024 published

The manuscript "Contrail altitude estimation using GOES-16 ABI data and deep learning" has been published on Atmospheric Measurement Techniques.

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Bulletin of Atmospheric Science and Technology paper Cimini et al. 2024 published

The manuscript "Anatomy of the uncertainty of satellite vicarious calibration using radiosondes: concepts and preliminary results for microwave…