Modeling transport, fate, and lifetime of riverine DOC in the Arctic Ocean

M. Manizza (1),  M. J. Follows (1), S. Dutkiewicz (1), C. N. Hill (1), D. Menemenlis (2), J. McClelland (3), B. Peterson (4) 

(1) EAPS-MIT, (2) NASA-JPL, (3) University of Texas, (4) Marine Biological Laboratory

We use a numerical model to examine the fate of riverine fluxes of dissolved organic carbon (DOC) in the
Arctic basin.  

The model is based on the Arctic sector of an eddy-permitting ocean model (MITgcm), where the
spherical domain is projected onto a cube to avoid polar a singularity in the Arctic region.

The physical model is forced by time-varying NCEP re-analysis products and an explicit representation of fresh water run-off in
the Arctic region.  

Passive tracers and idealized "DOC" tracers are explicitly represented, transported by the
prognostic circulation fields. 

The tracers have sources near the mouths of major Arctic river systems,
distributed in space and time according to observational estimates of regional DOC discharge. 

The DOC-like tracers have a finite, tunable lifetime in the water column. Comparison of a suite of model sensitivity studies
with observed tracer relationships from the region suggest that the model captures the main circulation
features and source distributions appropriately. 

Tracer relationships in the model match those observed most closely when the
lifetime of riverine source DOC is about 1 year.

We will discuss the role of the riverine DOC sources in regulating regional
air-sea carbon fluxes in the context of a more complete biogeochemical model.