The GCOS Upper-Air Network (GUAN) serves specifically the needs of global climate applications and has been established mainly on the basis of existing GOS networks. It forms a minimum configuration required for global applications for upper-air.
The the spacing of GUAN stations is set at 5 to 10 degrees latitude, sufficient to resolve synoptic-scale waves. The desired parameters are temperature, pressure (geopotential height), wind, and humidity (at least in the troposphere).
The inclusion criteria are:
- Commitment by National Meteorological and Hydrological Services with regard to continuity
- Length and quality of historical time series
- Current measurement quality
The purposes of the GUAN are the following:
- To establish national commitments for the preservation of a minimum set of upper-air stations for the foreseeable future
- To build a collection of validated data from these stations in standardized formats
- To provide this information to the global climate community with no formal restriction
The following table is the 2018 summary for the GCOS Upper-Air Network (GUAN) monitoring against the GCOS minimum requirements (25 daily soundings to 30hPa per month) for each region, according to the monthly statistics provided by NCEP. In brackets are the same statistics for 2017, 2016, 2015, 2014, 2013, 2012 and 2011. For 2012 and 2011 these are based on availability according to NCEI.
| Region | Number of GUAN stations | % meeting minimum GCOS requirements in 2018 (% for 2017, 2016, 2015, 2014, 2013, 2012 and 2011) |
|---|---|---|
| RA-I | 23 | 22% (30%, 39%, 35%, 39%, 46%, 48%, 57%) |
| RA-II | 38 | 87% (89%, 87%, 87%, 87%, 87%, 87%, 87%) |
| RA-III | 18 | 72% (61%, 61%, 67%, 72%, 67%, 89%, 78%) |
| RA-IV | 24 | 92% (92%, 87%, 79%, 83%, 75%, 83%, 87%) |
| RA-V | 38 | 79% (79%, 84%, 79%, 76%, 74%, 84%, 87%) |
| RA-VI | 24 | 87% (87%, 87%, 87%, 87%, 83%, 92%, 87%) |
| Antarctica | 12 | 67% (67%, 58%, 67%, 58%, 58%, 83%, 83%) |
The current state of GUAN and its performance indicators are provided by the Global Observing Systems Information Center.
A report on the network perfomance in 2018 is available here.
