David W. J. Thompson

TL;DR: The Arctic Oscillation (AO) as mentioned in this paper is the signature of modulations in the strength of the polar vortex aloft, and it resembles the NAO in many respects; but its primary center of action covers more of the Arctic, giving it a more zonally symmetric appearance.

TL;DR: In this article, the authors compared the structure and seasonality of the Southern Hemisphere (SH) annular mode and the Northern Hemisphere (NH) mode, referred to as the Arctic Oscillation (AO), based on data from the National Centers for Environmental Prediction and National Center for Atmospheric Research reanalysis and supplementary datasets.

TL;DR: In this article, it is argued that the largest and most significant tropospheric trends can be traced to recent trends in the lower stratospheric polar vortex, which are due largely to photochemical ozone losses, and the trend toward stronger circumpolar flow has contributed substantially to the observed warming over the Antarctic Peninsula and Patagonia and to the cooling over eastern Antarctica and the Antarctic plateau.

TL;DR: In this paper, the authors exploit the remarkable similarity between recent climate trends and the structure of the "annular modes" in the month-to-month variability (as described in a companion paper) to partition the trends into components linearly congruent with and linearly independent of the annular modes.

TL;DR: The recent trend in the NAM toward its high-index polarity with stronger subpolar westerlies has tended to reduce the severity of winter weather over most middle- and high-latitude Northern Hemisphere continental regions.