Mass Fluctuations in the Midlatitude North Atlantic Ocean at Nonseasonal Timescales

Abstract:

Measurements from the Gravity Recovery and Climate Experiment reveal spatially coherent nonseasonal fluctuations in ocean bottom pressure (OBP) in the midlatitude North Atlantic. The spatial structure of the OBP anomalies is centered on the North Atlantic Current along the intergyre region separating subtropical and subpolar ocean basins, and their temporal behavior is tied to indices of climate variability, namely, the North Atlantic Oscillation and the Arctic Oscillation. Correspondence to variations in wind stress curl suggests an interpretation of the midlatitude North Atlantic OBP variability in terms of a barotropic Sverdrup balance. Anomalous mass in the midlatitude North Atlantic Ocean covaries with mass anomalies in abutting marginal seas, including the Mediterranean Sea and the Arctic Ocean as well as the North Sea and Hudson Bay. Results have implications for diagnosing ocean meridional heat transports due to depth-independent gyre circulation changes.