HR: 1340h
AN: B23A-0932    [Abstracts]
TI: Extending the record of photosynthetic activity over the eastern United States into the pre-satellite period using surface diurnal temperature range
AU: * Bonfils, C
EM: celine@atmos.berkeley.edu
AF: Berkeley Atmospheric Sciences Center, University of California, Berkeley, CA 94720 United States
AU: Angert, A
EM: angert@atmos.berkeley.edu
AF: Berkeley Atmospheric Sciences Center, University of California, Berkeley, CA 94720 United States
AU: Henning, C
EM: henning@atmos.berkeley.edu
AF: Berkeley Atmospheric Sciences Center, University of California, Berkeley, CA 94720 United States
AU: Biraud, S
EM: scbiraud@lbl.gov
AF: Berkeley Atmospheric Sciences Center, University of California, Berkeley, CA 94720 United States
AU: Doney, S C
EM: sdoney@whoi.edu
AF: Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543 United States
AU: Fung, I
EM: inez@atmos.berkeley.edu
AF: Berkeley Atmospheric Sciences Center, University of California, Berkeley, CA 94720 United States
AB: In this study, we demonstrate that mid-latitude surface measurements of diurnal temperature range (DTR) can be used to reconstruct decadal variability of spring, summer and fall terrestrial photosynthetic activity during and prior to the period with satellite retrievals of land surface greenness. The two relative maxima present in the seasonal evolution of DTR can determine the beginning and the end of the growing season of plants, and summertime average DTR can be used as a proxy of summertime terrestrial photosynthesis variability. In a case study over the eastern United States (1966-1997), we found from the DTR reconstructions significant decadal variability in photosynthetic activity. Satellite-observed positive trends in spring and summer photosynthetic activity are consistent with natural decadal variability and thus are not indicative of a secular, human induced trend. Comparison with temperature and precipitation data shows that summertime photosynthesis activity is primarily controlled by moisture availability while the timing of spring onset depends on both temperature and moisture conditions.
DE: 9350 North America
DE: 3322 Land/atmosphere interactions
DE: 1818 Evapotranspiration
DE: 0315 Biosphere/atmosphere interactions
DE: 0322 Constituent sources and sinks
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting