Eric Hunt (Atmospheric and Environmental Research, Inc.), Jordan Christian (University of Oklahoma), Jeff Basara (University of Oklahoma), Jason Otkin (University of Wisconsin-Madison), Robb Randall (Army Research Laboratory), Katie McGaughey (USDA-FAS)
The 2010 heatwave across western Russia was an extreme event that led to profound environmental, economic, and societal impacts. Thousands of people were displaced due to catastrophic loss of property from wildfires (Bondur 2011) and severe air pollution from the fires significantly increased mortality during the late summer when the frequency and spatial extent of the wildfires were at its peak (Shaposhnikov et al., 2014). In all, the resulting impacts associated with the heatwave and air quality problems led to a total of approximately 11,000 deaths. Previous research had shown a quasi-stationary upper level ridge and land-atmosphere temperature coupling as the primary components for the development of the heatwave event. However, the results in this study (Christian et al, 2020 in review) reveal that rapid drought intensification occurred prior to the extreme atmospheric conditions associated with the heatwave.
Our research shows that rapid drought intensification occurred prior to the extreme atmospheric conditions associated with the heatwave. The flash drought event developed from a lack of rainfall coupled with enhanced evaporative demand and resulted in a rapid desiccation of the land surface. Figure 1a (left) shows that the flash drought began over a large area of southwestern Russia in May and had high rates of intensification (Figure 1b, right). This area also corresponds to the southwestern Russia wheat belt, which experienced grain harvests well below 50% of expected production (Wegren 2011). As a result of the drastic reduction in expected production, export bans on grains were imposed by the Russian government in August 2010 which significantly increased prices in the global market (Welton 2011).
Figure 1. Grid points identified with flash drought development during 2010 with a) the month in which flash drought began and b) the flash drought intensity (rate of intensification toward drought).
The region in southwestern Russia that underwent rapid drought intensification acted to prime the land-atmosphere interactions necessary to supplement the excessive surface temperatures experienced during the heatwave event while also providing a source region for the advection of warm, dry air to promote heatwave development downwind of the flash drought location. As such, the hydrometeorological extremes associated with the precursor flash drought and heatwave resulted in cascading impacts that severely affected ecosystems, agriculture, and human health.
The spatial extent and temporal evolution of the flash drought event across the region shown in Figure 1 was analyzed using a comprehensive identification methodology in conjunction with a standardized evaporative stress ratio (SESR; Christian et al., 2019). SESR is a reanalysis-based variant of the satellite-based evaporative stress index (ESI; Anderson et al., 2007) that has also been used extensively in flash drought research. In this research, SESR was derived from the ratio of evapotranspiration (ET) and potential evapotranspiration (PET) from the NASA Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2; Gelaro et al., 2017).
This work was supported by the National Aeronautics and Space Administration (NASA) Water Resources Program grant 80NSSC19K1266.
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