A SIMULATION OF A LARGE POSITIVE CO2 ANOMALY OVER THE CANADIAN ARCTICARCHIPELAGO

A 3-dimensional dynamical regional atmospheric model was used to inves tigate the quantitative relationship between the physical processes of long range CO2 transport from the emission region in Eurasia, and til e magnitude and duration of a CO2 anomaly measurement over the Canadia n Arctic. We chose to simulate a positive CO2 anomaly episode of about 5 ppm observed at Alert, located at the northern tip of Ellesmere Isl and, during early December of 1990. The simulation allowed us to exami ne the evolution of the spatial distribution of the CO2 anomaly field as it was being transported from the emission region in northern Europ e to Siberia, and then across the Arctic Ocean to the Canadian Arctic. The anthropogenic CO2 took more than a week to reach eastern Siberia, and stayed there until a synoptic situation evolved to finally advect it across the pole to the Canadian side. With the industrial emission from the northern Eurasia as the only CO2 source, the model was able to simulate an intrusion of a CO2 anomaly field into the Canadian Arct ic of little less than 2 ppm. With the inclusion of land biospheric CO 2 sources, the model was able to account for much of the remaining 3 p pm. The positive CO2 anomaly observed at Alert on December 1 represent s a ''classical'' case of a low-level transport of CO2 from Eurasia, v ia northern Siberia, to the Canadian Arctic during a winter season cha racterized by a very strong inversion in the lower troposphere.