RATIONALE :
In this project we aim to model the basin-scale circulation of the Arctic Ocean and quantify
the air-sea fluxes of CO2 in order to have a preliminary budget of the contemporary carbon cycle of the Arctic Ocean.
We will use numerical models that are strictly related with the ECCO2 project. MITgcm is the primary
core from where we build our numerical model. We run simulations with a version Arctic Ocean regional version
of MITgcm. We also couple to the physical model, a series of tracer model to address different questions :
1) Riverine Dissolved Organic Carbon (DOC)/Salinity relationship :
Field data suggest that in the Arctic Ocean,
the relationship between riverine DOC and salinity is pretty robust.
We use a simple tracer model where we prescribe
the time scale of decay of an idealized tracer. The time evolution of a simple passive tracer is
governed by the advection and diffusion equations implemented in MITgcm. We add a third term
that determines the decay of our tracer in time. This decaying term aims to simulate the effect of degradation
of dissolved organic carbon carried out by marine bacteria. We assume that our pure passive tracer (without any time scale
of decay) can be treated as salinity in our numerical experiments.
In collaboration with Jim McClelland and Bruce Peterson we built a basin scale climatology
of DOC discharge for the major rivers of the Arctic Ocean, for both Eurasian and North American side.
We implemented in our Arctic Ocean MITgcm the DOC climatology and we run a suite of simulations where we explore different time scales of degradation (1 month, 6 months, 1 year, 10 years).
Analysis of these simulations is in progress.
2) Arctic Ocean Carbon Budget :
The primary goal of this study is to have numerical model to calculate the air-sea fluxes of carbon dioxide (CO2)
for the entire Arctic basin. We will a regional version of MITgcm configured for the Arctic basin.
MITgcm is forced by re-analyzed data (NCEP) for the period roughly spanning from year 2000 to present.
The physical model is forced by heat fluxes, wind stress and it prognostically computes physical and dynamical properties
of the physical ocean. This version of MITgcm also has a prognostic sea-ice model
This version of MITgcm has been kindly set-up for us by Dimitris Menemenlis and Chris Hill in the contest of ECCO2 project (funded by NASA).
We plan then to couple an ocean biogeochemical to the physical model in order to compute all the biogeochemical
properties of the ocean that affect CO2 fluxes.
Data of CO2 fluxes in the Arctic Ocean collected throughout the years by field scientists are very sparse in time and space.
We plan to progress in this work in collaboration with our colleague Nick Bates to come up with a robust carbon budget for
the Arctic Ocean combining both model output and real data.
3) Arctic Region Carbon Budget :
The final goal of the SASS project is to determine a robust estimate of the fluxes of CO2 that cycle among the different compartments
such as the land biosphere, the ocean and the atmosphere.
Results from terrestrial ecosystem model, ocean biogeochemical model will be integrated with atmospheric inversions carried out by the group
of Ron Prinn (MIT) to have a final budget for the carbon cycle for the Arctic region.
4) Water Masses Formation & Age in the Arctic Ocean (in collaboration with Peter Winsor, University of Alaska, Fairbanks)
We will use the regional set-up of the Arctic Ocean based on MITgcm
to study the ventilation processes and estimate the age of water masses inside
the Arctic basin. This study is based on the combination of model results and observational
estimates derived by several Arctic cruises.