The Impact of Interannual Variability on Air-Sea CO2 fluxes and Oceanic Dissolved Inorganic Carbon Fields: Numerical Experiments in the NCAR CSM Ocean Model (NCOM)
NOAA/DOE OACES, 36 months
PROJECT SUMMARY
The preliminary analysis of the WOCE/JGOFS global ocean carbon survey has contributed greatly to an improved understanding of the mean and perturbed state of the ocean carbon cycle. The global carbon data set and associated new data analysis techniques have helped to clarify among other issues the air-sea CO2 flux fields, the natural dissolved inorganic carbon background distributions, and the long-term uptake patterns of anthropogenic carbon. A decade long, one-time global survey, however, is less useful for constraining the temporal variability of the ocean, for which we will have to turn to more directed measurement programs and numerical models. Here, I propose to evaluate the impact of interannual climate variability on the ocean carbon system using a state of the art numerical global ocean circulation model, the NCAR CSM Ocean Model (NCOM), driven with synoptic atmospheric forcing data sets either from the NCEP reanalysis (1957-1996) or the coupled NCAR Climate System Model.
The analysis of the resulting model variability in the air-sea CO2
flux and subsurface dissolved inorganic carbon distribution will be focused
on two related questions: what is the oceanic contribution to the observed
variability in the atmospheric CO2 growth rate?, and what type
of sampling strategy is needed to quantify the long-term uptake of anthropogenic
carbon given the natural background variability? Particular emphasis
will be given to examining the physical and biological mechanisms governing
variability in the model and their relevance to the real ocean. Oceanic
and atmospheric carbon observations will be used extensively to validate
both the mean state and variability of the ocean carbon model in collaboration
with a number of co-investigators (D. Schimel, NCAR; I. Fung, UC Berkeley;
R. Wanninkhof, NOAA/AOML). This study will provide also a framework
for interpreting the WOCE/JGOFS global CO2 survey and designing
optimal future sampling networks.
Scott Doney
Climate and Global Dynamics
National Center for Atmospheric Research
P.O. Box 3000
Boulder, CO 80307
tel: (303) 497-1639
fax: (303) 497-1700
doney@ncar.ucar.edu
http://www.cgd.ucar.edu:80/oce/doney/doney.html