HR: 1340h
AN: B33A-0241    [Abstracts]
TI: Was the Enhanced CO2 Sink Following the Mt. Pinatubo Eruption Driven by an Increase in Diffuse Radiation?
AU: * Angert, A
EM: angert@atmos.berkeley.edu
AF: Berkeley Atmospheric Sciences Center, University of California, Berkeley., 307 McCone Hall, Berkeley, CA 94720-4767 United States
AU: Biraud, S
EM: SCBiraud@lbl.gov
AF: Berkeley Atmospheric Sciences Center, University of California, Berkeley., 307 McCone Hall, Berkeley, CA 94720-4767 United States
AU: Bonfils, C
EM: celine@atmos.berkeley.edu
AF: Berkeley Atmospheric Sciences Center, University of California, Berkeley., 307 McCone Hall, Berkeley, CA 94720-4767 United States
AU: Buermann, W
EM: buermann@atmos.berkeley.edu
AF: Berkeley Atmospheric Sciences Center, University of California, Berkeley., 307 McCone Hall, Berkeley, CA 94720-4767 United States
AU: fung, I
EM: inez@atmos.berkeley.edu
AF: Berkeley Atmospheric Sciences Center, University of California, Berkeley., 307 McCone Hall, Berkeley, CA 94720-4767 United States
AB: Was the Enhanced CO2 Sink Following the Mt. Pinatubo Eruption Driven by an Increase in Diffuse Radiation? Following the Mt. Pinatubo eruption in 1991 there was a sharp decrease in the atmospheric CO2 growth rate. It is believed that this decrease was caused by an anomalous strong terrestrial sink (approx. 2PgC/yr) in the northern hemisphere. This strong sink is hard to explain, since the global low temperatures that followed the eruption (as a result of the injecting of volcanic aerosols to the stratosphere) were expected to reduce photosynthesis rate. There are currently two competing explanations for the enhanced sink. The first is that soil respiration rate declined more than photosynthesis rate, while the second suggests that the increase in the fraction of diffused radiation, as a result of the aerosol loading, caused an increase in photosynthesis. In this study we used a biogeochemical model (CASA) linked to an atmospheric tracer model (MATCH) with interannually varying transport, to predict the atmospheric CO2 response to the various hypotheses for the enhanced sink. By comparing the modeled CO2 growth rate, and seasonal minimum with observation from the CMDL global CO2 monitoring network, we found that global Net Primary Production could not have increased following the eruption. We also found that the enhanced sink cannot be explained by decreased respiration alone, and thus can be only explained by several land and ocean sink mechanisms acting in concert.
DE: 1610 Atmosphere (0315, 0325)
DE: 1615 Biogeochemical processes (4805)
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting