The Central Geophysical Observatory in Belsk Duży

The Central Geophysical Observatory in Belsk Duży (COG), operated by IGF PAS, is a background station conducting a wide range of geophysical measurements. It is located in the Mazovian Lowland, at an altitude of 190 meters above sea level. The surrounding area is mainly composed of agricultural fields and fruit orchards. The Warsaw agglomeration, located approximately 50 km away, has minimal influence on measurements conducted in Belsk. In the field of atmospheric physics, the station performs basic observations of air pollution, trace gases, and incoming radiation. Pollution concentrations remain low for most of the year, with the exception of winter episodes linked to residential coal combustion. This makes COG an excellent site for analyzing long-term trends in atmospheric parameters and for observing long-range advection episodes.

The aerosol measurement component of the ACTRIS network is currently under development. A sun photometer is already in operation, passively measuring the amount of direct and scattered solar radiation reaching the surface. By mid-2026, a complete set of in-situ aerosol measurement instruments will be installed, providing data on optical and microphysical parameters that define the concentration and type of observed pollutants.