North Atlantic air-sea interactions driven by atmospheric and oceanic stochastic forcing in a simple box model

Abstract

"North Atlantic (NA) variability has wide-spread implications locally and globally. This study investigates mechanisms driving NA variability using a simple box model incorporating time evolution of interacting upper ocean temperature anomalies, horizontal (Gyre) and vertical (meridional overturning circulation, or MOC) circulation, driven by surface air temperature, wind, and Labrador Sea temperature forcings. Simulated upper ocean responses to external atmospheric forcing result in solutions with redder spectra than solutions by white noise atmospheric forcing, implying that the ocean acts as a low-pass filter to this external forcing. Simulated ocean dynamic response may be viewed as a response to a cumulative atmospheric forcing over an interval defined by system damping properties. A strong anti-correlation links simulated MOC and Gyre circulation intensity suggesting a mechanism, in which system heat balance is maintained via communication between the dynamic components, (e.g. excess of heat supply from a stronger Gyre circulation would be balanced by lack of heat from a weaker MOC circulation and vise versa). Wind was the dominant forcing for NA upper ocean temperature anomalies and the intensity of MOC and Gyre circulations. Further investigations of NA variability mechanisms are important as they have serious implications on global heat transport"--Leaf iii.