HR: 1330h
AN: A52A-0761    [PDF]
TI: Regional Impact of Terrestrial Ecosystem on Global Carbon Cycle: Indicated by Isotopic Measurements of Atmospheric CO2 at Boreal Forest (Fraserdale, Canada)
AU: * Huang, L
EM: lin.huang@ec.gc.ca
AF: Air Quality Research Branch, Meteorological Service of Canada, 4905 Dufferin street, Toronto, ON M3h 5T4 Canada
AU: Tans, P
EM: ptans@cmdl.noaa.gov
AF: CMDL/NOAA, 325 Broadway R/CMDL, Boulder, CO 80305-3328 United States
AU: Higuchi, K
EM: kaz.higuchi@ec.gc.ca
AF: Air Quality Research Branch, Meteorological Service of Canada, 4905 Dufferin street, Toronto, ON M3h 5T4 Canada
AU: Shashkov, A
EM: alexander.shashkov@ec.gc.ca
AF: Air Quality Research Branch, Meteorological Service of Canada, 4905 Dufferin street, Toronto, ON M3h 5T4 Canada
AU: Norman, A
EM: annlisen@phas.ucalgary.ca
AF: University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4 Canada
AU: White, J
EM: james.white@colorada.edu
AF: University of Colorado, Campus Box 450, Boulder, CO 80309 United States
AU: Chan, D
EM: douglas.chan@ec.gc.ca
AF: Air Quality Research Branch, Meteorological Service of Canada, 4905 Dufferin street, Toronto, ON M3h 5T4 Canada
AU: Worthy, D
EM: doug.worthy@ec.gc.ca
AF: Air Quality Research Branch, Meteorological Service of Canada, 4905 Dufferin street, Toronto, ON M3h 5T4 Canada
AB: Eight intensive campaigns were conducted in different seasons over a 3-year period (1998 to 2000) at a boreal forest site, Fraserdale ($50\deg$N, $81\deg$W) in northern Ontario, Canada. Flask air samples were taken both at the 20-m level of a 40-m tower and from aircraft profiles (six campaigns), and were analyzed for both CO2 concentration and their isotopic compositions ($\delta^{13}C$ and $\delta^{18}O$). The results from these intensive campaigns are compared with Marine Boundary Layer (MBL) data at the same latitude, derived from the observations obtained by the CMDL/NOAA cooperative air sampling network, in order to understand the impact of regional sources and sinks on global carbon cycle. The amplitude of variation in each ground campaign and the difference between the campaigns and MBL show typical seasonal patterns for both CO$_{2}$ concentration and isotopic compositions, with smaller values in the winter, and larger values in the summer and Fall, reflecting the strength and balance of regional sources/sinks driven by ecosystem processes. The most interesting discovery is that the minimum value of $\delta^{18}O$ from Fraserdale campaign data occurs in the September - October period, which does not match the minimum value of $\delta^{18}O$ in local precipitation (the latter occurs in December - January) but matches the pattern of MBL $\delta^{18}O$ in mid-high latitudes of the Northern Hemisphere. This indicates Sept. and Oct. are a very active time of year for CO$_{2}$ isotope exchange with soil water and that $\delta^{18}O$ of the respiration flux from the local ecosystem has a significant imprint on $\delta^{18}O$ in global background air (MBL). Similar comparisons are also applied to aircraft flask samples. Less variation (including daily and seasonal changes) and less difference between campaigns and MBL are found in aircraft data; and MBL and the aircraft data closely agree with each other. Comparison of ground and aircraft campaign data with MBL compositions reveals very valuable information for understanding the processes of propagation of terrestrial biosphere signals into global background values of the atmospheric compositions (CO$_{2}$, $\delta^{13}C$ and $\delta^{18}O$), and the impact of regional sources and sinks on global carbon cycle.
DE: 1610 Atmosphere (0315, 0325)
DE: 1615 Biogeochemical processes (4805)
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting