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
| Region |
Number
of GUAN stations
|
% meeting minimum GCOS requirements in 2016
(% for 2015, 2014, 2013, 2012 and 2011)
|
| RA-I |
23 |
39% (35%, 39%, 46%, 48%, 57%) |
| RA-II |
32 |
87% (87%, 87%, 87%, 87%, 87%) |
| RA-III |
18 |
61% (67%, 72%, 67%, 89%, 78%) |
| RA-IV |
24 |
87% (79%, 83%, 75%, 83%, 87%) |
| RA-V |
38 |
84% (79%, 76%, 74%, 84%, 87%) |
| RA-VI |
24 |
87% (87%, 87%, 83%, 92%, 87%) |
| Antarctica |
12 |
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 2017 is available here.
