Pacific and Atlantic Ocean influences on multidecadal drought frequency in the United States

TLDR

Long‑term drought predictability may largely depend on the multidecadal behavior of the North Atlantic Ocean. The study proposes that if the current warm North Atlantic (positive AMO) continues, two drought scenarios similar to the 1930s and 1950s continental patterns may occur. The analysis shows that 52 % of multidecadal drought frequency variance is driven by the Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation, with an additional 22 % linked to a unidirectional climate trend, and recent widespread droughts corresponded to warm North Atlantic and cool Pacific conditions.

Abstract

More than half (52%) of the spatial and temporal variance in multidecadal drought frequency over the conterminous United States is attributable to the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO). An additional 22% of the variance in drought frequency is related to a complex spatial pattern of positive and negative trends in drought occurrence possibly related to increasing Northern Hemisphere temperatures or some other unidirectional climate trend. Recent droughts with broad impacts over the conterminous U.S. (1996, 1999–2002) were associated with North Atlantic warming (positive AMO) and northeastern and tropical Pacific cooling (negative PDO). Much of the long-term predictability of drought frequency may reside in the multidecadal behavior of the North Atlantic Ocean. Should the current positive AMO (warm North Atlantic) conditions persist into the upcoming decade, we suggest two possible drought scenarios that resemble the continental-scale patterns of the 1930s (positive PDO) and 1950s (negative PDO) drought.