AER helps define Flash Droughts
In a new research article published in the Bulletin of American Meteorological Society, AER helped to define the proper meaning and use of the term flash drought. Given the increasing use of the term flash drought by the media and scientific community, the authors felt it was prudent to develop a consistent definition that can be used to identify these events and to understand their salient characteristics. In this paper, it was proposed that the definition for flash drought should explicitly focus on its rate of intensification rather than its duration, with droughts that develop more rapidly than usual identified as flash droughts. Thus, flash droughts should be viewed as a subset of drought. The authors identified two primary reasons for this approach. First, longevity and impact are fundamental characteristics of any drought. Thus, short-term events lasting only a few days and having minimal impacts should not be considered flash droughts. Second, by focusing on their rapid rate of intensification, the proposed flash drought definition highlights the unique challenges faced by vulnerable stakeholders who have less time to prepare for adverse effects when drought develops so quickly. In cases such as the 2012 flash drought, the impacts to agricultural and ecological systems were calamitous, costly, and covered a large portion of the central U.S. For monitoring the evolution of a flash drought, the authors proposed using indices and metrics that are robust, location agnostic, and time sensitive to rapid changes in soil moisture, evapotranspiration, vegetation health, and evaporative demand. Two of the flash drought monitoring examples cited were the Rapid Change Index (RCI) and a two-category reduction on the U.S. Drought Monitor over a month for a specific location. We hope this paper increases the understanding of flash drought in the future and in assessment of historical events.