Global warming is likely to exacerbate droughts, and these conditions are especially likely in regions including the Midwest, according to a newly developed prediction method from Argonne National Laboratory. The technique will help with understanding “flash droughts,” which come on quickly and might only last a few weeks.

“While conventional droughts are related to a prolonged lack of precipitation, flash droughts occur because of high temperatures and extremely high evaporation rates,” Rao Kotamarthi, an Argonne environmental scientist, said in a news release.

The method is based on highly detailed regional climate models and advanced computing. The more accurate models and predictions can help decision-makers to create better resilience strategies. 

Modern measurement

Conventional drought assessment methods rely on the lack of precipitation to identify drought. The Argonne scientists used a new method called vapor pressure deficit that uses temperature and relative humidity. 

VPD determines the difference between how much water vapor the air can hold when it is saturated and the total amount of water vapor available. An extended period of above-average VPD could mean a drought is occurring.

Existing analyses typically use weekly or monthly data, so drought identification is delayed. The new method uses daily data and can identify flash droughts more quickly.

“We’re looking at drought differently by bypassing precipitation altogether — to primarily look at the effect of temperature and future temperature changes on drought,” said Argonne environmental scientist Brandi Gamelin. Cold air retains less moisture than hot air. Therefore, “the warmer the air temperature, the more water vapor it can hold, which can draw moisture out of the surface, drying it out.”

More powerful tools

Other work at Argonne, in collaboration with NASA and the Pennsylvania State University, provides an easier way to pair complex data with weather instrument observations to create highly accurate climate models and forecast predictions. The Earth Model Column Collaboratory is the new, open-source tool.

Conventional climate models often simplify some of their representations because of limitations with computing, which creates uncertainty in the results. The Earth Model Column Collaboratory is a more powerful modeling platform and simulator that processes data better to provide more detailed models.

Researchers and the public can use and modify the open-source platform’s models. Argonne scientists anticipate the tool will help reduce uncertainties in rainfall predictions, among other environmental effects of climate change.