Investigating the Influence of Surface Heat Flux on the North Atlantic Circulation and Global Climate


OCCI Funded Project: 2007


The circulation in the North Atlantic Ocean greatly influences the climate of the surrounding countries. The high heat capacity of the large-scale ocean currents makes it possible for the Atlantic water to warm the atmosphere in the surrounding countries quite significantly. Understanding how the ocean responds to variations in global forcing is, naturally, an important ingredient in any climate scenario, especially those dealing with the North Atlantic sector. In particular, I propose to answer the following question: How do changes in the surface buoyancy forcing of the North Atlantic Ocean influence the strength of the horizontal flow between the equator and the polar regions? I propose to investigate, both analytically and experimentally, the response of such horizontal flow, and consequently of the North Atlantic overturning circulation, to changes in the surface buoyancy forcing in the presence of background rotation. I will conduct laboratory experiments using a new infrared technology which allows a free adjustment of the temperature in the tank.Fresh water will be heated from above by an infra-red lamp, and then, as the warm water will move away from the heat source, it will naturally cool at the surface. This forcing is similar to that in the ocean, which absorbs solar radiation in a relatively thin surface layer at low latitudes and loses most of this energy through evaporation at higher latitudes. New scaling laws will also be developed in which the length and temperature scales are obtained as a function of the radiative forcing, rather than being imposed by the geometry of the experiment. Previous studies used fixed temperature and/or fixed heat flux forcing. The novelty of the proposed study is the presence of background rotation together with the new forcing technique described above. Finally, the proposed research will assist in the understanding of how future or past changes in the North Atlantic Ocean surface buoyancy forcing affect the overturning circulation and the climate of the surrounding regions. The project will be performed in collaboration with a visiting European scientist.