2026/01/07 by Simon H. Lee · 1 voice
paper · doi:10.5281/zenodo.18174360
This dataset contains the daily year-round weather regime classification for North America from 1 January 1979 to 31 December 2025, based on ECMWF ERA5 reanalysis. The regimes are computed following the method outlined in "A New Year-Round Weather Regime Classification for North America" (Lee et al. 2023), originally defined for 1979–2022. The method uses seasonally variance-normalised, domain-average detrended 10-day low-pass filtered 500 hPa geopotential height anomalies in the region 20–80°N, 180–30°W. For full information on the computation of the regimes, please consult the reference paper in Journal of Climate. This classification uses four regimes: Pacific Trough (PT), occurring on 25.5% of days Pacific Ridge (PR), occurring on 21.4% of days Greenland High (GH), occurring on 19.6% of days Alaskan Ridge (AKR), occurring on 19.5% of days There is an additional "No Regime" class, defined to have a zero mean anomaly, which occurs on the remaining 14.0% of days. Each day is attributed to a single regime based on the minimum Euclidean distance to a cluster centroid in a 12-dimensional principal component space. This dataset also contains a time series of the continuous Weather Regime Index (WRI), defined following Lee and Messori (2024). The WRI is the standardised projection of each day's seasonally normalised 500 hPa geopotential height anomalies onto the cluster mean, and provides information on the relative amplitude of each pattern. Annual updates to this dataset are planned.