The Standardized Wind Speed Index: a multiscalar indicator of wind speed variability with a focus on wind droughts

This research proposes for the first time a new multiscalar indicator to evaluate wind speed conditions using a standardized index: The Standardized Wind Speed Index (SWSI). The SWSI has the advantage that allows spatial and temporal comparability and facilitates the interpretation of windier phases but also prolonged periods of low wind speeds or wind droughts, which are the main focus of this research. Typically, wind droughts have been evaluated and defined in terms of their impact on the wind industry, a crucial element in the transition to greener energy sources. The SWSI fills a gap left by operational definitions, enabling wind droughts to be characterized not only as short-term energy risks but also as long-term climatological phenomena with broader environmental implications. The study used observed global monthly near-surface wind speed data from the HadISD database for 1973–2023. A parametric approach has been followed, testing 10 different statistical distributions. After applying various tests, the Generalized Logistic distribution has been selected for the definition of the SWSI. This index enables the evaluation of wind speed conditions regionally and globally on different spatio-temporal scales (1-, 3- and 12-month); yet any desired time-scale can be used. Here we also show the robustness of the SWSI in detecting two extreme wind drought events occurred in USA (2015) and UK (2021) with strong decreases in primary energy production.