Reduced Moisture Transport Linked to Drought Propagation Across North America

Abstract

Droughts can have devastating societal impacts. Yet, we do not fully understand the mechanisms that control their development, possibly affecting our ability to predict them. Here we run a moisture-tracking analytical model using reanalysis data between 1980 and 2016 to explore the role of reduced moisture transport in drought propagation. We find that agricultural droughts in multiple subregions across North America may be amplified by decreased moisture transport from upwind land areas, which we link to reduced evapotranspiration and dry soil moisture upwind. We also find that decreases in precipitation recycling are correlated with decreases in moisture arriving from upwind areas. We estimate that decreases in moisture contributions from land areas accounted for 62% of the precipitation deficit during the 2012 Midwest drought. Our results suggest that the land surface may contain useful information for drought prediction and highlight the importance of sustainable land use and of regional cooperation for drought risk management.