The GRUAN station FMI-ARC in Sodankylä Finland organized an atmospheric sounding campaign in early 2010, which included participants from several countries. The first phase of the campaign was focussing on radiosonde inter-comparisons that were carried out in January-February 2010. Different commercial and research grade in situ instruments were launched with a focus on the comparison of humidity and temperature measurements in the troposphere and stratosphere.
Guidelines for all instruments will be developed and guidelines for the CFH are in progress. A team composed of different GRUAN participants using the same kind of instrument (such as the CFH or any other type of instrument) could take up this task. This would indeed be highly beneficial. The lead centre may motivate the formation of such groups.