There are National Focal Points for GCOS and related Climatological Data in more than 100 countries. An updated list of national focal points is available at the WMO CountryProfile Database.
Their Terms of References are:
Liaise within the National Meteorological and Hydrological Services on GCOS related networks (including GSN and GUAN) issues related to data availability and quality
Inform the INFCOM (WMO Commission for Observation, Infrastructure and Information Systems) Lead Centres for GCOS on current and potential problems that might impact data availability and quality
Respond to requests from the GCOS Secretariat and Lead Centres for GCOS regarding metadata, and data availability and quality