Bridging the Annular Mode and North Atlantic Oscillation paradigms

North Atlantic Oscillation / Annular Mode: Two Paradigms - One Phenomenon

The "North Atlantic Oscillation (NAO)" as defined in Walker and Bliss (1932) has been traditionally viewed as a teleconnection pattern with 'centers of action' in the Atlantic sector. In contrast, the "zonal index cycle", as articulated by Namias (1950), involves the interactions between a fundamentally zonally symmetric or 'annular’ mode and the eddies. The perceived dynamical significance of ...

Atmospheric Processes Governing the Northern Hemisphere Annular Mode/ North Atlantic Oscillation

Local and hemispheric dynamics of the North Atlantic Oscillation, annular patterns and the zonal index

In this paper we discuss the atmospheric dynamics of the North Atlantic Oscillation (NAO), the zonal index, and annular patterns of variability (also known as annular modes). Our goal is to give a unified treatment of these related phenomena, to make explicit how they are connected and how they differ, and to illustrate their dynamics with the aid of an idealized primitive equation model. Our f...

A Mechanism and Simple Dynamical Model of the North Atlantic Oscillation and Annular Modes

A simple dynamical model is presented for the basic spatial and temporal structure of the large-scale modes of intraseasonal variability and associated variations in the zonal index. Such variability in the extratropical atmosphere is known to be represented by fairly well-defined patterns, and among the most prominent are the North Atlantic Oscillation (NAO) and a more zonally symmetric patter...

On the Zonal Structure of the North Atlantic Oscillation and Annular Modes

The zonal structure and dynamics of the dipolar patterns of intraseasonal variability in the extratropical atmosphere—namely, the North Atlantic Oscillation (NAO) and the so-called annular modes of variability—are investigated in an idealized general circulation model. Particular attention is focused on the relationships linking the zonal structure of the stationary waves, synoptic variability ...