The Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) is an international reference observing network, established in 2006, 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 high-quality climate data records from the surface, through the troposphere, and into the stratosphere.

calendar_today Interval/period: Sun, 01/01/1978 - Wed, 10/17/2018

This dataset provides access to two types of ozone observations: total column ozone estimates and vertical profiles of ozone concentration.
The total ozone estimates are based on solar UV radiation measurements made by ground-based spectrophotometers (Dobson or Brewer type spectrophotometers).
The vertical profiles of ozone concentration are estimated primarily using ozonesonde observations.
Data are available for 159 Dobson stations, 109 Brewer stations and 135 ozonesondes stations.

calendar_today Interval/period: Tue, 01/01/1924 - Sun, 05/10/2026

This dataset provides estimates of water vapour derived from atmospheric delays in Global Navigation Satellite System
(GNSS) radio signals.
The initial data is collected from two in situ ground-based network of GNSS receivers – the International GNSS Service
(IGS) and EUREF Permanent Network (EPN). The IGS collects, archives, and freely distributes GNSS data from a
cooperatively operated global network of more than 500 ground-based GNSS stations since 1994. The EPN is a European

calendar_today Interval/period: Mon, 01/01/1996 - Sun, 05/10/2026

This catalogue entry provides access to vertical profiles of standard meteorological variables. It includes two archives.
The first is version 2 of the Integrated Global Radiosounding Archive (IGRA) from 1978 which incorporates global
radiosounding profiles of temperature, humidity and wind from a large number of data sources,
which is 30% larger than the previous version 1. IGRA v2 is the result of quality assurance procedures applied to the

calendar_today Interval/period: Sun, 01/01/1978 - Sun, 05/10/2026

This dataset provides monthly means of mass-consistent, vertically integrated, atmospheric energy and moisture budget quantities derived from 1-hourly ERA5 reanalysis data.
The vertically integrated budget diagnostics include the tendencies and lateral fluxes of total energy, water vapour, and latent heat (with the latent heat of vaporization varying with temperature). In addition, the divergences of the lateral fluxes are provided.

calendar_today Interval/period: Mon, 01/01/1979 - Sun, 05/10/2026

The present UERRA dataset contains analyses of atmospheric variables on height levels, from 1961 to 2019.

calendar_today Interval/period: Thu, 10/18/2018 - Wed, 07/31/2019

The present UERRA dataset contains analyses of atmospheric variables on pressure levels, from 1961 to 2019.
It has been generated using the UERRA-HARMONIE system by combining model data with observations into a complete and consistent dataset using the laws of physics.

calendar_today Interval/period: Thu, 10/18/2018 - Wed, 07/31/2019

This UERRA dataset contains analyses of surface and near-surface essential climate variables from
UERRA-HARMONIE and MESCAN-SURFEX systems. Forecasts up to 30 hours initialised
from the analyses at 00 and 12 UTC are available only through the CDS-API (see Documentation).
UERRA-HARMONIE is a 3-dimensional variational data assimilation system,
while MESCAN-SURFEX is a complementary surface analysis system.
Using the Optimal Interpolation method, MESCAN provides the best estimate of daily accumulated precipitation

calendar_today Interval/period: Thu, 10/18/2018 - Wed, 07/31/2019

Upper Tropospheric Humidity (UTH) is of key importance to the Earth’s greenhouse effect and understanding of climate change. It is considered an Essential Climate Variable (ECV) because it controls key atmospheric processes, including those involved in water vapour and cloud feedbacks, that can amplify the climate system’s response to increases in other greenhouse gases. The Upper Tropospheric Humidity is defined as the integrated amount of Water Vapour in the atmospheric layer between ~500 hPa and ~200 hPa.

calendar_today Interval/period: Tue, 07/05/1994 - Sun, 02/28/2021

Cloud properties directly influence the state of the Earth´s upper-air atmosphere. Clouds have an effect on weather and climate through their contribution to the Earth’s water cycle and impact on the Earth’s energy budget. They impact atmospheric motions on a range of spatial and temporal scales and contribute to changes in the atmospheric composition.

calendar_today Interval/period: Mon, 01/01/1979 - Mon, 06/30/2025

ERA5 is the fifth generation ECMWF atmospheric reanalysis of the global climate covering the period from January 1940 to present. It is produced by the Copernicus Climate Change Service (C3S) at ECMWF and provides hourly estimates of a large number of atmospheric, land and oceanic climate variables. The data cover the Earth on a 31km grid and resolve the atmosphere using 137 levels from the surface up to a height of 80km. ERA5 includes an ensemble component at half the resolution to provide information on synoptic uncertainty of its products.

calendar_today Interval/period: Sat, 01/01/1949 - Sun, 05/10/2026

The UERRA datasets contain reanalysis data of the atmosphere, the surface and near-surface as well as for the soil covering Europe. Essential climate variables are generated with the UERRA-HARMONIE and the MESCAN-SURFEX systems. UERRA-HARMONIE is a 3-dimensional variational data assimilation system, while MESCAN-SURFEX is a complementary surface analysis system.

calendar_today Interval/period: Thu, 10/18/2018 - Wed, 07/31/2019

The Comprehensive Upper-air Observation Network (CUON) dataset is designed
to contain all available observations from balloons ascents through the atmosphere.
The main geophysical variables are temperature, humidity, and wind speed and wind direction,
as functions of atmospheric pressure levels. The observation platforms include pilot balloons, radiosondes, and ozonesondes.
The main observation data sources are:
- the NOAA Integrated Global Radiosonde Archive (IGRA version 2),
- the NCAR Upper-Air Database (UADB), and

calendar_today Interval/period: Tue, 01/01/1901 - Tue, 12/31/2024

The Earth’s Radiation Budget (ERB) represents the overall balance between incoming and outgoing radiant energy at the Earth’s top-of-the-atmosphere. This Essential Climate Variable is the primary forcing of the climate system and is therefore a fundamental quantity to be monitored to understand the Earth’s climate and its variability. The Earth’s Radiation Budget comprises of the quantification of the incoming radiation from the Sun and the outgoing reflected shortwave and emitted longwave radiation.

calendar_today Interval/period: Mon, 01/01/1979 - Sun, 02/01/2026

ERA5 is the fifth generation ECMWF reanalysis for the global climate and weather for the past 8 decades.
Data is available from 1940 onwards.
ERA5 replaces the ERA-Interim reanalysis.

calendar_today Interval/period: Mon, 01/01/1940 - Sat, 05/02/2026

ERA5 is the fifth generation ECMWF reanalysis for the global climate and weather for the past 8 decades.
Data is available from 1940 onwards.
ERA5 replaces the ERA-Interim reanalysis.

calendar_today Interval/period: Mon, 01/01/1940 - Sat, 05/02/2026

ERA5 is the fifth generation ECMWF reanalysis for the global climate and weather for the past 8 decades.
Data is available from 1940 onwards. ERA5 replaces the ERA-Interim reanalysis.

calendar_today Interval/period: Mon, 01/01/1940 - Fri, 12/06/2024

ERA5 is the fifth generation ECMWF reanalysis for the global climate and weather for the past 8 decades.
Data is available from 1940 onwards.
ERA5 replaces the ERA-Interim reanalysis.

calendar_today Interval/period: Mon, 01/01/1940 - Wed, 04/01/2026

ERA5 is the fifth generation ECMWF reanalysis for the global climate and weather for the past 8 decades.
Data is available from 1940 onwards.
ERA5 replaces the ERA-Interim reanalysis.

calendar_today Interval/period: Mon, 01/01/1940 - Wed, 04/01/2026

ERA5 is the fifth generation ECMWF reanalysis for the global climate and weather for the past 8 decades.
Data is available from 1940 onwards.
ERA5 replaces the ERA-Interim reanalysis.

calendar_today Interval/period: Mon, 01/01/1940 - Sat, 05/02/2026

ERA5 is the fifth generation ECMWF reanalysis for the global climate and weather for the past 8 decades.
Data is available from 1940 onwards.
ERA5 replaces the ERA-Interim reanalysis.

calendar_today Interval/period: Mon, 01/01/1940 - Sat, 05/02/2026

Atmospheric water vapor, quantified here as Total Column Water Vapor (TCWV), holds paramount importance in monitoring and understanding Earth's climate dynamics. Its role as an Essential Climate Variable is pivotal, serving as the foundation for cloud formation, cloud physics, and significantly impacting the Earth's heat budget through its proficient absorption of both long and short-wave radiation.
This catalogue entry presents two extensive, high-quality observational datasets of TCWV, specifically tailored for climate analysis and applications.

calendar_today Interval/period: Tue, 01/01/2002 - Sun, 12/31/2017

Water vapour is has been recognised as an Essential Climate Variable as it provides the basis for all cloud formation and physics and furthermore influences the Earth's heat budget due to its high absorbance of long and short-wave radiation. Total column water vapour (TCWV) is a measure of the integrated water vapour content of the atmosphere.
This catalogue entry provides the TCWV data product usually called Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data (HOAPS).

calendar_today Interval/period: Wed, 05/01/2002 - Thu, 03/01/2012

This entry covers pressure-level data post-processed for bias adjustment on a monthly time resolution.

calendar_today Interval/period: Sun, 01/01/2017 - Fri, 05/01/2026

This entry covers single-level data post-processed for bias adjustment on a monthly time resolution.

calendar_today Interval/period: Sun, 01/01/2017 - Fri, 05/01/2026