Oceanic Teleconnections for Climate Changes in Arctic/Sub-Arctic and Tropical/Sub-Tropical Atlantic Oceans

A main mechanism which links climate changes in the Arctic/sub-Arctic regions to the lower-latitude oceans is through the Meridional Overturning Circulation (MOC) and the propagation of Kelvin and Rossby waves. The MOC is driven in part by the deep-water formation in the Nordic and Labrador Seas where the surface water density is strongly influenced by the flux of sea ice and low-salinity water from the Arctic. The MOC is forced by two major processes, the overflow of Nordic Sea water through Denmark Strait and Faroe Bank Channel, and the open ocean convection in the Labrador Sea. Kelvin and Rossby waves are generated as the transient responses of these two processes to an Arctic forcing. They propagate to the low-latitude oceans and affect oceanic circulation and heat content there. The response of the Nordic Sea overflow and Labrador-Sea convection to the Arctic forcing can be very different, especially when the wind-stress forcing and bottom topography are considered. So the their impacts on the tropical and subtropical Atlantic Ocean are different. Results from data analyses and process models will be used to explain how these two processes are affected by the sea-ice flux from the Arctic and how the tropical and subtropical Atlantic Ocean respond to changes of the Nordic Sea overflow and deep convection in the Labrador Sea.