An example of a particularly successful step forward in implementing a global observing system for climate is the initiation of a reference network for upper-air observations - the GCOS Reference Upper-Air Network (GRUAN).<ref>{{cite news |title= GCOS Reference Upper-Air Network |publisher=GCOS |year= 2013 |url= http://www.wmo.int/pages/prog/gcos/index.php?name=GRUAN|accessdate= 2013-11-05}}</ref> The network is the prototype of a hybrid observing system, combining operational upper-air measurement sites with research sites and providing high-quality reference data for atmospheric profiles. GRUAN sites are undertaking high-quality atmospheric profile measurements that will help understand trends in upper-air ECVs, assist in investigating processes in the upper-troposphere and lower stratosphere, and provide data for calibrating satellite measurements and validating independent climate analyses and models. At GRUAN sites, the principles of quality, traceability and complete error characterization have been heeded, for at least part of the observing programme. The network is planned to grow over its initial size of 15 stations in coming years; introducing climate quality standards to a larger number of sites. | An example of a particularly successful step forward in implementing a global observing system for climate is the initiation of a reference network for upper-air observations - the GCOS Reference Upper-Air Network (GRUAN).<ref>{{cite news |title= GCOS Reference Upper-Air Network |publisher=GCOS |year= 2013 |url= http://www.wmo.int/pages/prog/gcos/index.php?name=GRUAN|accessdate= 2013-11-05}}</ref> The network is the prototype of a hybrid observing system, combining operational upper-air measurement sites with research sites and providing high-quality reference data for atmospheric profiles. GRUAN sites are undertaking high-quality atmospheric profile measurements that will help understand trends in upper-air ECVs, assist in investigating processes in the upper-troposphere and lower stratosphere, and provide data for calibrating satellite measurements and validating independent climate analyses and models. At GRUAN sites, the principles of quality, traceability and complete error characterization have been heeded, for at least part of the observing programme. The network is planned to grow over its initial size of 15 stations in coming years; introducing climate quality standards to a larger number of sites. |