Abstract
The spatial and temporal evolution of winter sea ice anomalies in the Labrador Sea and associated sea surface temperature (SST) variations in the North Atlantic are documented for three periods of aboveânormal ice cover: 1972â1974, 1983â1985, and 1990â1992. These events are notable for their winterâtoâwinter persistence, despite the fact that the ice margin retreats to northern Baffin Bay each summer, and for their spatial evolution, progressing from the northern Labrador Sea to the southern tip of Newfoundland over a 3 year period. Aboveânormal sea ice is consistently accompanied by belowânormal SSTs in the subpolar Atlantic: the latter persist 1â3 years after the decay of the ice anomalies and in some cases exhibit a tendency for eastward movement across the gyre. Springâsummer freshwater anomalies at 100 m depth in the West Greenland Current are found to precede by âŒ8 months the initial occurrence of aboveânormal ice cover in the northern Labrador Sea. The role of atmospheric forcing in the joint evolution of anomalous sea ice and SST is assessed by means of an iceâocean mixed layer model forced with observed air temperature and wind fields. The model results indicate that thermodynamic atmospheric forcing accounts for much of the winterâtoâwinter persistence and spatial evolution of the ice and concurrent SST anomaly patterns. However, the subsequent persistence of SST anomalies in the subpolar region is not well simulated, suggesting that oceanic processes omitted from the simple slab mixed layer formulation play a contributing role.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have