A Reanalysis of North American Net Carbon Dioxide Exchange From 2000- 2006

We present the results from a carbon cycle reanalysis based on atmospheric carbon dioxide measurements in the period 2000-2006. This reanalysis contains weekly CO2 flux estimates for more than 150 ecosystems worldwide, with a special focus on North America. The reanalysis results from the assimilation of more than 20,000 CO2 mixing ratio observations in an ensemble system recently completed at NOAA ESRL. In addition to traditional background air samples of CO2, it uses continuous records from continental tall- tower sites to inform on sub-continental flux patterns and magnitudes. Our results confirm the terrestrial biosphere in North America to be a net sink of CO2 over this period of a little more than 0.5PgC/yr, significant at the 68% confidence level. Inter-annual variability over this short time span is substantial though, and appears driven by large-scale drought conditions. Classified by dominant vegetation type, the North American carbon sink in our results is strongest in croplands (30% of sink), followed by coniferous forests (20%), deciduous broadleaf forests (20%), and grasslands(15%). In addition to an analysis of 6 years of North American carbon exchange, we will present details on how to access the full global reanalysis on-line from NOAA ESRL's web pages.