The high altitude research station Jungfraujoch (7° 59' E, 46° 32' N, 3580 m a.s.l.) is situated on a mountain saddle in the central Swiss Alps between the Jungfrau (4158 m a.s.l.) in the West and the Moench (4099 m a.s.l.) in the East. The International Foundation High Altitude Research Stations Jungfraujoch and Gornergrat (HFSJG) runs the research station and provides the infrastructure and support for scientific research. Due to its unique place, the year-round accessibility, and the excellent infrastructure, the Jungfraujoch research station is well suited for long-term ground-based monitoring of trace gas concentrations trends in the free troposphere. Due to its location in central Europe and its proximity to anthropogenic greenhouse gas source regions it is also an appropriate study site for European regional source allocations during pollution events. The research activities of EMPA at the Jungfraujoch are conducted within the scope of the Swiss National Air Pollution Monitoring Network (NABEL) funded by the Swiss Federal Office for the Environment (FOEN) and the Global Atmosphere Watch Program (GAW) of the World Meteorological Organization (WMO). The measurement programme at Jungfraujoch includes continuous in-situ analyses of ozone (O3), carbon monoxide (CO), nitrogen monoxide (NO), nitrogen dioxide (NO2), and the sum of nitrogen oxides (NOy). In addition, an extended set of halocarbons and a selection of VOCs (alkanes, aromatics) are measured with a time resolution of four hours since 2000 as a part of SOGE. Daily samples are taken for determination of gaseous SO2 and for particulate sulphur. The concentrations of total suspended particles are continuously observed as well as measured as 48-hour bulk samples. Measurements of methane, nitrous oxide and sulphur hexafluoride were commenced in February 2005 funded by the FOEN. Therefore, the whole set of non-CO2 greenhouse gases is now continuously monitored at the Jungfraujoch.