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GCOS Upper-Air Network (GUAN)

The GCOS Upper-Air Network (GUAN) is a program of the Global Climate Observing System (GCOS). The GUAN consists of stations selected from the Global Observing System of the World Weather Watch.

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Program Management

The Atmospheric Observation Panel for Climate (AOPC) was established to define the requirements for meteorological observations for GCOS. AOPC is responsible for the planning and implementation of GUAN in cooperation with the World Weather Watch of the WMO.

Data Management

The Hadley Centre of the UK Met Office and the NCEI act as joint data analysis centers for GUAN. Their responsibilities are:


  • Update and quality control daily data
  • Apply bias adjustments to daily data
  • Calculate monthly statistics (MONADS) from the bias-adjusted daily data
  • Report on historical and metadata reception and improve metadata
  • Provide daily and monthly data to users

The Hadley Centre

  • Improve monthly station data base
  • Improve bias adjustments to monthly data
  • Analyze monthly upper air data
  • Provide grid products with reduced biases
  • Create global and regional monthly statistics

Data Management Procedures

  • Original data, quality-controlled data, and bias-adjusted data (from any instrument or network) are all to be retained, along with flags indicating quality and source of data. (For radiosondes, these requirements apply to all stations, not just GUAN).
  • NCEI no longer maintains and distributes data from the Comprehensive Aerological Reference Data Set (CARDS). It has been superseded by the Integrated Global Radiosonde Archive (IGRA). IGRA consists of radiosonde and pilot balloon observations at over 1500 globally distributed stations.

Performance Indicators

Additional Information