Landfalling Droughts: Global Tracking of Moisture Deficits From the Oceans Onto Land

Journal Article · Mon Sep 21 00:00:00 EDT 2020 · Water Resources Research

DOI:https://doi.org/10.1029/2019WR026877· OSTI ID:1664638

Herrera‐Estrada, Julio E.  ^[1]; Diffenbaugh, Noah S.  ^[2]

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1. Descartes Labs, Inc. New York NY USA, Department of Earth System Science Stanford University Stanford CA USA, Program on Water in the West Stanford University Stanford CA USA, Stanford Data Science Initiative Stanford University Stanford CA USA
2. Department of Earth System Science Stanford University Stanford CA USA, Woods Institute for the Environment Stanford University Stanford CA USA

Abstract Droughts threaten food, energy, and water security, causing death and displacement of millions of people and billions of dollars in damages. However, there are still important gaps in the understanding of drought mechanisms and behaviors, inhibiting the accuracy of early‐warning systems designed to protect communities worldwide. We use an object‐tracking algorithm to track clusters of precipitation‐minus‐evaporation moisture deficits across land and ocean areas of the globe from 1981–2018. This analysis reveals a new type of “landfalling drought” that originates over the ocean and “migrates” onto land. We find that 16% of droughts that affected the continents worldwide from 1981–2018 were landfalling droughts. These droughts were significantly larger (220–425%) and more intense (4–30%)—and grew (253–285%) and intensified (9–28%) faster—than droughts that developed solely over the land or ocean. To identify potential underlying mechanisms, we analyze moisture transport associated with landfalling droughts over western North America. We find that landfalling droughts in this region are associated with anomalously anticyclonic atmospheric pressure patterns that reduce moisture fluxes over the Pacific Ocean toward the continent. By advancing understanding of the spatiotemporal evolution of droughts, our findings offer the potential to improve seasonal‐scale prediction and long‐term projection of global drought risks.

• Sponsoring Organization: USDOE
• OSTI ID: 1664638
• Alternate ID(s): OSTI ID: 1786877
• Journal Information: Water Resources Research, Journal Name: Water Resources Research Vol. 56 Journal Issue: 9; ISSN 0043-1397
• Publisher: American Geophysical Union (AGU)
• Country of Publication: United States
• Language: English