Characteristics and trends of flash droughts in Spain, 1961–2018

• Published in: Annals of the New York Academy of Sciences Vol. 1472; no. 1; pp. 155 - 172
• Main Authors: Noguera, Iván, Domínguez‐Castro, Fernando, Vicente‐Serrano, Sergio M.
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01-07-2020
• Subjects: atmospheric evaporative demand; Drought; Environmental impact; Evaporation; flash drought; Spain; Spatial discrimination; Spatial resolution; SPEI; time scale; Trends; Spain; time scale; atmospheric evaporative demand; flash drought; SPEI; Spain
• ISSN: 0077-8923; 1749-6632
• DOI: 10.1111/nyas.14365

Flash droughts are characterized by rapid onset and intensification, as well as major environmental and agricultural impacts. In this study, we developed an objective method for identifying flash droughts using the standardized evaporation precipitation index (SPEI) based on a short time scale (1‐month) and high‐frequency data (weekly). The identification of flash droughts was focused on the development phase, anomalous decreases in index values in a short time period (4 weeks), and the magnitude of the events. The method was applied to mainland Spain and the Balearic Islands using a high spatial resolution gridded dataset for the period 1961–2018. For this period of 58 years, we characterized the occurrence of flash droughts and showed that for Spain, there was a large spatial and temporal variability in their frequency, with more occurring in the northwest than in the central and southern regions. The northern regions, where a higher frequency of flash droughts was found, showed negative trends in the frequency of flash droughts, while the regions subject to fewer flash drought events showed generally positive trends. We investigated the relative frequency of flash droughts affecting the study regions and found that they are a common phenomenon, as 40% of all droughts were characterized by rapid development. The findings of this study have important implications for drought assessment, monitoring, and mitigation.
Flash droughts are characterized by rapid onset and intensification, as well as major environmental and agricultural impacts. In this study, we developed an objective method for identifying flash droughts using the standardized evaporation precipitation index (SPEI) based on a short time scale (1‐month) and high frequency data (weekly). This method was applied to mainland Spain and the Balearic Islands using a high spatial resolution gridded dataset for the period 1961–2018.