The CSIC has developed the first global system for detecting extreme weather events such as ‘wind droughts’
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The Centre for Research on Desertification (CIDE, CSIC-UV-GVA) is developing an index that identifies periods of high wind or low wind, a tool for quantifying wind availability
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In addition to wind energy production, this system provides valuable information on a phenomenon with implications for air quality, soil erosion and urban heat islands
A study led by the Centre for Research on Desertification (CIDE), a joint centre of the Spanish National Research Council (CSIC), the University of Valencia (UV) and the Valencian Regional Government, has developed the first standardised index to assess wind speed variability worldwide, a system that compares wind conditions across different regions and years. This tool enables the identification and characterisation of extreme events such as wind droughts—prolonged periods of low wind speed with significant economic repercussions for the wind energy industry. Furthermore, the index values influence air quality, soil erosion, evaporation and urban heat islands. The study is published in the journal Atmospheric Research.
The development of the first standardised climatological index to assess wind variability, the Standardised Wind Speed Index (SWSI), begins with the collection of historical wind speed data from across the globe over a representative period: the study incorporates data from 2,264 weather stations between 1973 and 2023, drawn from six sub-regions across the Americas, Asia, Europe and Oceania. This data is then subjected to quality control and standardisation, and transformed into a standardised probability scale with values ranging from -3 to +3. Zero represents the historical average wind speed for that area and time of year. Minor variations are considered within the normal climatic range; positive values reflect abnormally windy periods, whilst negative values indicate a deficit or ‘wind drought’. Return periods can also be extrapolated, with the time representing an estimated average between two events of the same intensity.
“This makes it possible to compare the severity of a wind drought in geographically distinct locations in a completely objective manner, regardless of whether their absolute wind speeds differ drastically,” explains Miguel Andrés Martín, a researcher at CIDE who led the study. To demonstrate the validity and accuracy of the index, they tested it against two of the most recent events with the greatest economic impact: the wind droughts in the United States (2015) and the United Kingdom (2021), which caused drops in wind energy production of up to 20%.
Widespread drought caused by the wind
“Our index confirmed the severity of the problem,” says the CSIC researcher. “The SWSI fell to -2.15 in the western United States, an extreme event that occurs only once every 63 years. The UK experienced its worst period of wind deficit in over a decade, and the SWSI allowed us to see that this was not a one-off dip, but a sustained wind drought throughout the year, with a return period of 70 years,” he summarises. “Evaluating the SWSI against these real-world episodes is a litmus test; it confirms that it is a robust and standardised tool for measuring, comparing and understanding these anomalies anywhere in the world,” he maintains.
Why do these windless spells occur? “In the short term, they are caused by atmospheric blockages: a persistent high-pressure system that acts as a barrier, blocking the wind. When they last for months, they are usually driven by changes in large-scale atmospheric circulation patterns,” argues César Azorín, a scientist at the CSIC and director of the Climatoc-Lab at CIDE. The phenomenon also has a long-term dimension: stilling, a trend towards weaker winds across the planet that the SWSI also detects. In fact, the study identified specific phenomena, such as the sustained accumulation of wind droughts in Europe since the late 1990s or a global wind deficit that lasted from 1995 to 2010. “Although wind levels have partially recovered since 2010, the index confirms that current values remain below those recorded forty years ago. Furthermore, climate scenarios point to further wind droughts in our latitudes as a result of global warming,” he asserts.
The lack of wind affects not only the wind power industry, but also air quality, as wind is responsible for dispersing air pollutants. A windless spell stagnates the air and causes pollution levels in cities to soar, affecting respiratory health. There is also the effect of urban heat islands: if the wind stops, the city loses its cooling capacity and the number of tropical or sweltering nights increases. Furthermore, wind patterns have a direct influence on the amount of water crops require and transpire, and anomalies in wind speed are a key factor in soil erosion, amongst other things.
Website launched to monitor the wind
A tool such as the SWSI index enables the collection of reliable data for designing urban layouts that promote natural ventilation in streets or for better protecting water and agricultural resources in the face of climate change. “Until now, wind droughts have been defined almost exclusively from the perspective of their impact on wind energy. However, this index introduces a standardised climatological approach that is not only applicable to wind energy, but also to studying wind as a climatic phenomenon with broader implications such as air quality, crop evapotranspiration, soil erosion and urban heat islands, among others,” summarises Miguel Andrés.
The CIDE Climatoc-Lab team is working on the development of a dedicated SWSI viewer to monitor historical and real-time wind data in Spain, which will enable users to assess wind speed conditions across different time scales. “This will enable authorities and users to assess changes in wind patterns and anticipate the impact of wind droughts across multiple socio-economic and environmental sectors,” concludes Azorín. This viewer will be available on the website of CIDE’s Climatoc-Lab, which is leading the study in collaboration with the Interdisciplinary Thematic Platform (PTI).Climate and Climate Services at the CSIC.
Referència:
Miguel Andres-Martin, Cessar Azorin-Molina, Sergio M. Vicente-Serrano, Robert J.H. Dunn, Nuria P. Plaza-Martín, Shalenys Bedoya-Valestt. The Standardized Wind Speed Index: a multiscalar indicator of wind speed variability with a focus on wind droughts, Atmospheric Research, Volume 338, 2026, 108967, ISSN 0169-8095. DOI: https://doi.org/10.1016/j.atmosres.2026.108967
CIDE Communications
