Impacts of the 2017 flash drought in the US Northern plains informed by satellite-based evapotranspiration and solar-induced fluorescence

Drought is increasing in frequency and severity, exacerbating food and water security risks in an era of continued global warming and human population growth. Here, we analyzed a severe summer drought affecting the US Northern Plains region in 2017. We examined the spatial pattern and seasonal progression of vegetation productivity and water use in the region using satellite-based estimates of field-scale (30 m) cropland evapotranspiration (ET), county level annual crop production statistics, and GOME-2 satellite observations of solar-induced chlorophyll fluorescence (SIF). The cropland ET record shows strong potential to track seasonal cropland water demands spatially, with strong correspondence to regional climate variables in the Northern Plains. The GOME-2 SIF record shows significant but limited correlations with finer scale climate variability due to the coarse sensor footprint, but captured an anomalous regional productivity decline coincident with drought related decreases in crop production and ET. The drought contributed to an overall 25% reduction in cropland ET, 6% decrease in crop production, and 11% reduction in SIF productivity over the region from April to September in 2017 relative to the longer (2008-2017) satellite record. More severely impacted agricultural areas indicated by the US Drought Monitor exceptional drought (D4) category represented 11% of the region and showed much larger anomalous ET (20%-81%) and productivity (11%-73%) declines. The regional pattern of drought impacts indicated more severe productivity and ET reductions in the north central and southern counties with extensive agriculture, and less impact in the western counties of the Northern Plains. This study provides a multiscale assessment of drought related impacts on regional productivity and ET over a crop intensive region, emphasizing the use of global satellite observations capable of informing regional to global scale water and food security assessments.