CAFE most significant results in the period 2019-2021, organized per scientific objective, are the following:
-Understanding the relation between Rossby Wave Packets (RWPs) and the large-scale environment through statistics:
Influence of ENSO and the Southern Annular Mode (SAM) on RWPs in the Southern-Hemisphere extratropics during austral summer, in particular for long-lived RWPs.
which opens an opportunity to better forecast extreme events during these conditions.
-Statistical characetrization of the Madden Julian (MJ) Oscillation events:
For size and duration of MJ events, a power law has been found to describe both the correlations and the tails of the distributions, which could affect the limits of predictability of the phenomenon.
-Development of diagnosis tools for identification and tracking of the MJ oscillation, blocking, and some other oceanic structures:
Coherent Lagrangian structures have been used to identify circulation patterns during atmospheric blocking. Harmonic closeness centrality identifies the location of the jet stream and its meanders.
-Classification of daily weather patterns (synoptic circulations) over Europe into eleven main categories. The evaluation of past and future trends in the seasonal frequencies of the weather types shows
that most of the trends arise from the SSP5-8.5 scenario in the summer. Results prove weather types associated to the most extreme rainfall.
-Correlation of El Niño-Southern Oscillation (ENSO) with extreme temperatures and extreme precipitation at a global scale have been performed, using diverse analysis methods (composition; correlation analysis, Granger causality).
-Circulation patterns are associated to heatwaves by means of an empirical orthogonal function analysis and a clustering algorithm.
Anti-cyclonic structures over certain European areas are found to occur together with cyclonic structures over neighbouring areas, pointing towards a blocking effect triggering the associated heatwaves.
-Development of machine-learning algorithms for the analysis of climatological phenomena, tested for MJO events, and obtaining similar skill to conventional methods.
-Assessment of the response of extreme weather events for different levels of stabilized global warming and comparison with their response to internal modes of climate variability such as ENSO or MJO.
climate networks linking different spatial points by means of correlations have been constructed, restricted to relative short windows (10 to 14 days). Several metrics characterizing the networks are revealing distinct signatures of tropical cyclones, in particular high clustering and low degree along the tropical-cyclone track.
-Development of a method to find maximally correlated structures between two spatial fields, with many potential applications. When applied to sea surface temperature and land precipitation trying to identify extremes, it yields very well-known climatological patterns as the successive resulting modes, among them the El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO).
-Extreme precipitation events (EPEs) in the Mediterranean region have been studied, paying attention to atmospheric variability in the lower and middle troposphere, using an empirical orthogonal function approach plus a clustering algorithm.
Both spatial (winter and autumn being the seasons of highest EPE frequency for the eastern and western Mediterranean, respectively) and temporal clusterings ( 20 % of the EPEs occurring up to 1 week after a preceding EPE) have been found.
12. Systematic quantification of the predictability potential of a stochastic weather generator of analogues of atmospheric circulation:
Development of a stochastic weather generator (SWG), based on the use of analogues, using as a variable the geopotential height at 500 hPa, related to large-scale circulations.
A pilot test to forecast precipitation in several European cities has delivered results with satisfactory skill up to 20 days in advance.
