Missing Potential Impact of Post-wildfire on 2012 U.S. Flash Drought

Abstract

A recent flash drought in 2012 summer caused over 100 deaths and $ 25 billion of economic losses in the Midwestern United States (MIDUS) due to failed forecast of the flash drought with a rapid onset. Prior to the 2012 flash drought, there were extensive wildfires in MIDUS region in late spring, March. Extensive wildfires highly have effects on the change in land covers by affecting surface water/energy budget and land-atmospheric fields. This study focuses on potential impacts of the extensive wildfires on the 2012 flash drought in MIDUS through large ensembles of WRF with change in land cover. Results show that latent heat fluxes are highly affected by the change in land cover, resulting in a contrast between direr top soil layer and wetter root-zone soil layer. Through the framework of convective triggering potential (CTP) and low-level humidity index (HI), we reveal that drier and hotter near-surface by post-wildfire drives drier land-atmospheric coupling. At large-scale, the effects of post-wildfire modulate a blocking system at middle troposphere and the warming of near-surface. This study suggests that wildfires are one of potential triggers of flash droughts and be considered to reduce the risk of 2012-like MIDSU flash drought.