Impact of ocean heat transport on Arctic sea-ice variability in the GFDL
CM2-O model suite
Abstract
The impact of horizontal resolution on meridional Ocean Heat Transport
(OHT) and sea ice in the Arctic is investigated using the GFDL CM2-O
climate model suite (1°, 1/4°, and 1/10°) in both preindustrial control
and climate change simulations. Results show an increase in OHT
associated to a decrease in sea ice extent (SIE) in the Arctic on
inter-annual and decadal time scales. This link, however, is not
monotonic with spatial resolution. While OHT increases and SIE decreases
from the Low to the Medium resolution, the reverse is true from the
Medium to the High resolution. Differences in OHT and SIE between the
three model configurations mostly arise from the preindustrial state. As
the spatial resolution increases, the Irminger Current is favored at the
expense of the North Atlantic Drift. This rerouting of water to the
Western side of Greenland results in less heat delivered to the Arctic
in the High resolution configuration than in its Medium counterpart. As
a result, the Medium resolution configuration is in best agreement with
observed SIE and Atlantic OHT. Concurrent with the change in the
partitioning in volume is a change in deep convection centers from the
Greenland-Irminger-Norwegian Seas in the Low resolution to the Labrador
Sea in the Medium and High resolutions. Results suggest a coupling
between OHT into the Arctic and deep convection in the North Atlantic.