Continuous time dimensions and persistence
a) The scatter plot displays the daily values of the instantaneous dimension d - the higher d, the more unpredictable is the atmospheric circulation - and the persistence θ - the lower θ the more stable is the atmospheric circulation - of the sea level pressure field (in hPa) extracted from the NCEP Database and the forecast up to 72h extracted from the GFS model. The trajectory for the last 7 days is displayed in colors. b) The weather regimes are computed as the days beyond the 0.15 quantiles of the d and θ distribution displayed in panel a). c) Distribution of the best 25 analogues per decades. d) Percentage of days of the same month in all the database with higher or lower dimensions d . e) Same as d) but for the persistence θ. See here for explanations. f) Sea-level pressure fields over the North-Atlantic showing the domain of the analysis and forecasts +24h, 48h, 72h.
The (d,θ) variables are available here. The file is provided 'as is'.