2003: North Atlantic response to the above-normal export of sea ice from the Arctic

• Main Authors: Oleg A. Saenko, Edward C. Wiebe, Andrew J. Weaver
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Arctic; North Atlantic; Sea ice
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.534.5751; http://www.cccma.ec.gc.ca/papers/osaenko/PDF/above_normal_ice_2003.pdf

[1] The response of the thermohaline circulation (THC), as well as the freshwater and heat budgets of the northern North Atlantic, to above-normal sea ice export from the Arctic is examined using a global model. The model is not constrained by either open boundary conditions or prescribed atmospheric air temperature and humidity. Two sets of experiments are presented: the transient and the persistent above-normal ice export. In the transient case, ice export is increased by a factor of 2 for 1–5 years. Our century-long simulations do not support the notion that the simulated climate may switch to a new quasi-equilibrium under such perturbations. Rather, in response to the transient positive ice export anomalies the overturning circulation first slows down but then almost completely recovers 15–20 years after the perturbation is removed. However, the budgets of freshwater and heat continue to evolve for up to 40 years in this case. When the simulated North Atlantic freshening reaches a magnitude comparable to that during the Great Salinity Anomaly (GSA), the strength of overturning and heat transport from subtropical to subpolar North Atlantic reduce by no more then 5%. We show that in order to generate a previously reported decrease of overturning and heat transport of as much as 20 % the