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gfdl's home page > gfdl on-line bibliography > 2001: The Oceans & Rapid Climate Change, 199-215
On the response of the Atlantic Ocean to climatic changes in high latitudes: sensitivity studies with a sigma coordinate ocean model
| Ezer, Tal, 2001: On the response of the Atlantic Ocean to climatic changes in high latitudes: sensitivity studies with a sigma coordinate ocean model. In The Oceans and Rapid Climate Change: Past, Present, and Future. Geophysical Monograph 126, Washington, DC: American Geophysical Union, 199-215. |
| Abstract: The oceanic adjustment processes during the transition from present climate conditions to atmospheric forcing conditions that are significantly different than present climate have been simulated with a sigma coordinate Atlantic Ocean model. An idealized "global warming" scenario has been simulated by imposing surface flux anomalies, representing warming and freshening in the high latitudes of the North Atlantic. The results show a relatively short oceanic adjustment process that takes place within a period of a few decades in which the thermohaline overturning circulation (THC) is adapted to a new state with a transport smaller by 4-5 Sv than that obtained with a control run without the surface anomalies. While the total change in the intensity of the THC in this ocean model is consistent with that obtained by coarse resolution coupled ocean-atmosphere climate models, this study shows a shorter adjustment time scale and more pronounced spatial changes than climate models do. Interesting results include a weakening and cooling of the Gulf Stream, reversal of the Labrador Sea circulation and considerable weakening in the deep western boundary current and in downslope near-bottom flows in high latitudes. Sensitivity experiments explore how the parameterization of horizontal diffusion in this sigma coordinate ocean model affects long-term climate simulations. These experiments show that horizontal diffusion in the model affects the transition process and local gyres, but the climate change in the THC and in the meridional heat flux are quite robust and insensitive to the way horizontal diffusion is parameterized in the model. |