The GMOS global network was established by integrating atmospheric Hg monitoring stations that were part of existing atmospheric monitoring programs (such as the World Meteorological Organization's Global Atmosphere Watch program (GAW), US and Canadian programs (i.e., NADP-MDN, CAPMoN), the UN-ECE's European Monitoring and Evaluation Program (EMEP) and the Arctic Monitoring and Assessment Program (AMAP)) with newly established GMOS sites located at both high altitude and sea level locations, in climatically diverse regions.
An effort was made to establish measurement sites in the Tropics and Southern Hemisphere where long-term Hg measurements were lacking before GMOS. GMOS monitoring sites have been classified in “Master” and “Secondary” sites. Master stations are those where Gaseous Elemental Mercury (GEM), Gaseous Oxidized Mercury (GOM), Hg associated to suspended particulate matter (PBM2.5) and Hg in precipitation are continuously measured. Secondary stations are those where only Total Gaseous Mercury (TGM) and Hg in precipitation are continuously measured.
The ground-based monitoring program ensures long-term collection of near-real time Hg data. An ad-hoc application was developed to retrieve automatically data or archive submitted information.
Data are acquired by the GMOS Cyber-(e)-Infrastructure and stored in the GMOS central databases. Site operators and managers can view near real-time trends. To guarantee data reliability and intercomparability, raw data from on-going GMOS sites are screened with an ad-hoc Quality Assurance and Quality Control validation tool. Once the validation process is complete the resulting dataset, are stored in the same harmonized format and available to partners from the password protected GMOS webpage for the Dissemination purpose.