Work Package 15: Physical-chemical feedbacks at high latitudes

Leader: Leif G. Anderson

Objectives
- To evaluate the correlation between sea-ice cover, biogeochemical properties as well as river
runoff distribution with partial pressure of CO2 in the northern North Atlantic and the Arctic
Ocean.
- To model the reactions of the carbon system to current fluctuations and changes of climate (temperature,
wind stress, precipitation, and ice cover) in the Southern Ocean and to evaluate the
model skill by comparison with observations.

Description of work
Northern high latitudes:
Historic data from the northern North Atlantic and the Arctic Ocean will be evaluated with respect
to the surface water pCO2 in relation to sea ice cover (per cent open water), biochemical properties
and runoff content of the surface water in order to detect any significant correlations. Historic data
of all relevant properties will be assembled and quality controlled, including high quality data over
a large part of the Arctic Ocean from 1987 to 2002 and from the Nordic Seas for an even longer
time period. New data of the carbon system will be collected during the Beringia expedition from
the Eurasian shelf seas and along a section from the Beaufort Sea to the Barents Sea (partner 32).
Southern high latitudes:
Physical controls (eddy strength, frontal dynamics) on biogeochemistry in the idealized setting of a
zonal channel, representing the Antarctic Circumpolar Current will be tested (new ecosystem model
REcoM that allows for a decoupling between the cycling of carbon and the nutrients nitrate and
phosphate coupled to an eddy-resolving version of the MIT general circulation model). the REcoM
ecosystem model will be extended to simulate also the cycling of silica and iron, both of which
strongly influence biological activity in the Southern Ocean. In order to quantify the strengths of
physical feedbacks over the Southern Ocean as a whole, a hemispheric or global coarser-resolution
version of the coupled REcoM-MIT model with 'optimal' physical trajectories will be developed.
(partner 3)