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


Meeting |

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…

Article |

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…


Meeting |

ICM-13: agenda available

Due to the global Covid-19 situation, this year's meeting will be organized as a condensed, virtual meeting in the week of 15-19 November 2021.

Article |

AMT paper Rosoldi et al. 2021 in review

"Intercomparison of Vaisala RS92 and RS41 radiosonde temperature sensors under controlled laboratory conditions" by Rosoldi et al. The paper is open…

Article |

AMT paper Lee et al. 2021 in review

"Radiation correction and uncertainty evaluation of RS41 temperature sensors by using an upper-air simulator" by Lee et al. The paper is open for…

Article Data product |

AMT paper von Rohden et al. 2021 in review

"Laboratory characterisation of the radiation temperature error of radiosondes and its application to the GRUAN data processing for the Vaisala RS41"…


Station |

Paramaribo (Suriname) first GRUAN site in South America

With the establishment of a new site in Paramaribo we have reached the landmark of the first GRUAN site on the South American continent. This is…

Article Measurement |

AMT paper Ingleby et al. 2021 in review

The following GRUAN-relevant paper was published at AMT: "On the quality of RS41 radiosonde descent data" by Ingleby et al. The paper is open for…


Conference |

ICM-13: virtual meeting 15-19 November 2021

In view of the ongoing Covid-19 situation, ICM-13 will again be organized as a virtual meeting.