Affiliation:
1. Department of Applied Physics and Applied Mathematics Columbia University New York NY USA
2. Department of Earth Sciences and Swedish Centre for Impacts of Climate Extremes (CLIMES) Uppsala University Uppsala Sweden
3. Department of Meteorology and Bolin Centre for Climate Research Stockholm University Stockholm Sweden
Abstract
AbstractWeather regimes have been defined over multiple regions and used in a range of practical applications, including subseasonal‐to‐seasonal forecasting and climate model evaluation. Despite their widespread use, the extent to which regimes reflect physical modes of the atmosphere is seldom investigated. Here, we adopt a year‐round classification of four North American weather regimes, with a fifth “no regime” class, and leverage dynamical systems theory to investigate their dynamical properties. We find that when the atmospheric flow is assigned to a regime, it displays persistent characteristics and a lifecycle‐like temporal evolution. We further find that, regardless of season, these characteristics are enhanced when the atmospheric flow displays a comparatively strong projection onto the cluster‐mean of the regime to which it is assigned (while the reverse is true for a weaker projection). We interpret these results as evidence that the four North American weather regimes are physically‐meaningful, with a clear dynamical footprint.
Funder
H2020 European Research Council
National Science Foundation
Publisher
American Geophysical Union (AGU)