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U.S. DOE researchers identify new way to predict droughts

September 19, 2022

Droughts are commonly defined by a “prolonged lack of precipitation.” However, rainfall or snowfall deficit alone may not identify a drought.

Argonne National Laboratory researchers are using a new measure called vapor pressure deficit (VPD). VPD is the difference between the air’s capacity to hold water vapor when saturated and the total amount of water vapor available. The environmental scientists explain that high temperatures and extremely high evaporation rates cause flash droughts.

The Standardized VPD Drought Index (SVDI) uses daily data, making it more useful than current drought monitoring indices which commonly rely on monthly data and lagging indicators of actual droughts.

The projected worsening of droughts … is likely to have significant consequences in terms of crop loss, wildfires, and demand for water resources,” said Rao Kotamarthi, author of the “Projected U.S. drought extremes through the Twenty-First Century with vapor pressure deficit” study published in Scientific Reports.

“An extended period of higher-than-average VPD can mean a drought is occurring,” said Brandi Gamelin, Argonne environmental scientist. “We’re primarily look(ing) at the effect of temperature and future temperature changes on drought” because hotter air typically has a higher VPD than colder air. “…The warmer the air temperature, the more water vapor it can hold, which can draw moisture out of the surface, drying it out,” added Gamelin.

The research was funded by a strategic partnership project with AT&T. The researchers used computing resources provided by the Argonne Leadership Computing Facility (ALCF), Argonne’s Laboratory Computing Resource Center, and the National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory. The ALCF and NERSC are DOE Office of Science user facilities.

To advance climate and environmental science, KISTERS designs and delivers a variety of meteorological sensors. WMO-quality precipitation gauges and weather sensors are deployed globally to support drought and flood prediction.