JUNE 2002: Detectability of net carbon uptake by North America
Somewhere at northern mid-latitudes there is a large terrestrial sink for atmospheric CO2, but where? Inverse analyses are trying to solve this problem by fitting results from global 3-D atmospheric transport models to the observed concentration gradients of CO2. These analyses rely primarily on measurements from the flask network of NOAA's Climate Monitoring and Diagnostics Laboratory. This figure shows the relative influence of the individual NOAA/CMDL sampling sites on an inversion estimate of net CO2 uptake by the North American terrestrial biosphere for the period 1988-1992; symbol size is proportional to site influence. The influence functions were calculated with a global 3-D model using GISS II' meteorology, as part of a study to investigate the sensitivity of inversion estimates to varying configurations of the observation network. We find that the stations most influential in determining net North American carbon uptake are those at the continental periphery that are also characterized by low levels of data uncertainty (e.g., KEY, SHM, STM). The small impact of certain continental stations (e.g., TAP, BAL) results from the high levels of data uncertainty at these sites. This work was conducted by Parvadha Suntharalingam and a full account is given in Suntharalingam et al. [2002] (pdf file).