D. Luo, Linhao Zhong, C. Franzke
Sep 11, 2015
Journal of the Atmospheric Sciences
AbstractIn this paper, based on a new wave–eddy interaction framework, the interaction mechanism between the North Atlantic Oscillation (NAO) and synoptic-scale eddies is revealed by using the analytical solutions of a two-scale model as a description of the inverse energy cascade from nonuniform synoptic-scale eddies to the large-scale NAO flow. It is found that the spatial shape of the eddy-induced large-scale streamfunction tendency prior to the NAO onset determines the direction of eddy energy transfer, as well as the phase and growth of the NAO. However, the feedback of the intensified NAO anomaly on synoptic eddies can affect significantly the asymmetry of the NAO between negative (NAO−) and positive (NAO+) phases in amplitude and persistence through the presence or absence of the eddy straining related to cyclonic wave breaking (CWB).For the NAO+, the stretching deformation role of the NAO+ field seems dominant in the eddy variation. Because the eddy energy generation rate (EGR) weakens and tends t...