Attach:gruuppe-52014.JPG Δ The global observational system for atmospheric biogeochemical trace gases consists of about 200 stations worldwide at which CO2 and related gases are regularly measured by flask sampling, typically with a frequency of 1-2 weeks. In recent past, this network has been extended by regular airborne vertical profile measurements and by the installation of continuous measurement systems on coastal and mountain sites, and over the continents on tall towers (>100 m).
The global observational system is, even with substantial efforts of many institutions, still far from covering adequately the entire globe. This is a fundamental limitation for current top-down modeling inversion studies. Critical gaps exist in so-called "hot-spot" areas, such as northern Eurasia and the tropical regions of Africa.
As part of a cooperative effort, the Tall Tower Atmospheric Gas Measurements (TAG) research group? is establishing measurement sites? along a west-east transect at about 60°N from the North Atlantic to Siberia, and along a north-south transect in the Eastern Atlantic Ocean. In addition, the TAG workgroup is dedicated to the development of atmospheric measurement techniques.