The Wisconsin site has become the focus of many studies funded by other agencies. It has been used for several years on board small private aircraft for the collection of approximately weekly vertical profiles at a site in northern Colorado. Our program is easily the most extensive global air sampling program of its kind, and we often provide a link for smaller programs to integrate their measurements into the global picture. We have found this to be an indispensable element of the quality control that is necessary for a confident merging of data obtained by different laboratories. Systematic measurement biases between different laboratories of as little as a few tenths of a ppm have the potential to seriously change conclusions regarding regional sources and sinks reached with the help of inverse models.
Work is ongoing to include more laboratories and update and improve the product.
The above activities result in a continuously updated database widely used by modelers to track the global carbon cycle. However, the rate of increase of CH 4 was high during 1998, probably related to the record warm temperatures of 1998. Masarie, K.A. and P.P. Tans, J. Geophys. Novelli, P.C., J.W. Elkins, and L.P. Steele, J. Geophys. R.A. Feely, R.F. Weiss, R.H. Wanninkhof, D.W. Chipman, S.C. Sutherland, and T.T. Takahashi, Proc.