The climate at our latitudes is influenced by synoptic-scale disturbances and atmospheric blocking. These blocks are recurring atmospheric configurations typical of mid-latitudes. Because such structures are characterized by preferential spatial distributions, significant changes in their extent, frequency, and/or positioning can lead to substantial changes in the local climate. Therefore, an adequate representation of these systems is crucial for accurately modeling mid-latitude climates and providing reasonable projections of future scenarios.

The aim of this activity is to identify useful criteria shared by the international scientific community for studying observed variability, long-term trends in the spatial properties of Rossby waves and associated atmospheric blocking conditions, as well as their future evolution based on global circulation models.

Referring to the state of the art on the subject, several methodologies for characterizing atmospheric blocking conditions have been identified, with particular interest in studies of Rossby waves and their propagation in the form of wave packets, known as Rossby Wave Packets (RWPs).

Based on well-established mathematical treatments, the WPA.m procedure was developed to characterize RWPs and their amplitude, starting from the southern wind velocity at 250 hPa.

Given the variety of atmospheric configurations that define a block, there is a range of definitions for “blocking index” and different additional criteria for identifying these systems in terms of minimum spatial extent, near-stationarity, and persistence. This makes comparison between different study methods challenging and requires analysis of multiple methodologies to gain greater confidence in the results, as blocking frequency has so far been poorly described by models.

For the characterization of blocking configurations, MiLES (MId-Latitude Evaluation System), a set of diagnostic procedures based on the R statistical package, was used, and some initial applications were conducted using ERA5 data.

The bibliographic research conducted and the software now available are the starting points for studying blocking configurations in relation to projected climate changes for the upcoming year’s activities.