You are here

Integrated Global Radiosonde Archive (IGRA)

Figure showing 4 maps

These maps show the locations of IGRA stations across the globe at several times throughout the record.


The Integrated Global Radiosonde Archive (IGRA) consists of radiosonde and pilot balloon observations at over 2,700 globally distributed stations. The earliest data date back to 1905, and recent data become available in near real time. Observations are available at standard and variable pressure levels, fixed- and variable-height wind levels, and the surface and tropopause. Variables include pressure, temperature, geopotential height, relative humidity, dew point depression, wind direction and speed, and elapsed time since launch.



Figure showing the number of stations per year.

This graph shows, for each year between 1905 and 2015, the number of IGRA stations reporting data.

IGRA consists of three components:

  • Individual soundings, organized into one file per station
  • Monthly means, organized into one file per variable and time of day (0000 and 1200 Universal Coordinated Time)
  • Sounding-derived parameters, organized into one file per station
  • In addition, IGRA station metadata are available to assist in the interpretation of the data. They include current station names and locations as well as information on changes in station location, instrumentation, and observing practices over time, to the extent that they are available.

The period of record of The IGRA data varies from station to station and among variables. Approximately 1,000 of the over 2,700 IGRA stations are currently reporting data. Vertical extent as well as temporal and vertical resolution also vary among stations and over time.

Recommended Uses and Limitations

IGRA is useful as input to air pollution models, for studies of the detailed vertical structure of the troposphere and lower stratosphere, for assessing the atmospheric conditions during a particular meteorological event, and for many other analyses and operational applications. NCEI scientists have applied a comprehensive set of quality control procedures to the data to remove gross errors. However, they did not attempt to remove jumps and other discontinuities caused by changes in instrumentation, observing practice, or station location. Users studying long-term trends may wish to use the NOAA Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC) or one of the available non-NOAA IGRA-derived, homogeneity-adjusted radiosonde datasets.


The current version of IGRA is Version 2. The most significant difference between IGRA V2 and IGRA V1 is the larger amount of data in IGRA V2, particularly before the 1970s. For the latest information on the status of IGRA, see the status file. To receive email notifications regarding changes to IGRA, please complete this Optional Registration Form.

Downloading IGRA Data

All IGRA-related information is provided in plain-text files.

Within each file, data appear in a deliberate order so as to make them as easy to read as possible for both humans and computer programs.

Alternate formats are presently not available.

The IGRA Team recommends that users review the following files prior to downloading the data:

  • Readme file describing differences between IGRA V1 and V2, what types of files are available, and where these files and their format documentation are located.​
  • Station Inventory
    This inventory contains the name, country, most recent location, network affiliation, and period of record of each station.
  • Country Codes
    This list contains the country names and codes that are useful when using the station list.

Two Download methods are available:

  • FTP
    Use the File transfer protocol (FTP) interface to download IGRA data. This interface works best for downloading a large number of files.
  • HTTP
    Use your browser to explore the folders containing IGRA-related files and download IGRA data one file at a time.

Additional Information

  • IGRA Station history information containing Information about changes in station location, instrumentation, and observing practices: For details, see the IGRA readme file.
  • Durre, I., R. S. Vose, and D. B. Wuertz, 2006: Overview of the Integrated Global Radiosonde Archive. Journal of Climate, 19, 53-68.
    Paper providing an overview of Version 1 of IGRA and the philosophy behind IGRA in general.
  • Durre, I., R. S. Vose, and D. B. Wuertz, 2008: Robust automated quality assurance of radiosonde temperatures. Journal of Applied Meteorology ands Climatology, 47, 2081-2095.
    Paper providing details about the quality control procedures applied to IGRA temperatures, applicable to Versions 1 and 2.
  • Durre, I., and X. Yin, 2008: Enhanced radiosonde data for studies of vertical structure. Bulletin of the American Meteorological Society, 89, 1257-1262.
    Paper describing the original version of the sounding-derived parameters. The methodology described in this paper also applies to IGRA V2.
  • Durre, I., and X. Yin, 2011: Enhancements of the dataset of sounding parameters derived from the Integrated Global Radiosonde Archive. 23rd Conference on Climate Variability and Change, Seattle, WA, 25 January 2011. [Available online at]
    Extended abstract describing additional parameters added to the sounding-derived parameters in 2011. IGRA V2 also contains these parameters.
  • Durre, I., C. N. Williams, Jr., X. Yin, and R. S. Vose, 2009: Radiosonde-based trends in precipitable · water over the Northern Hemisphere: An update. Journal of Geophysical Research, 114, D05112, doi:10.1029/2008JD010989.
    Paper describing the method for calculating the precipitable water values that are included in the sounding-derived parameters.

Contact Information

Technical Information

Technical Questions

Customer Support