‘Traveling’ droughts bring new possibilities for prediction.
A small subset of the most intense droughts move across continents in predictable patterns, according a new study published in the journal Geophysical Research Letters by researchers in Austria and the United States.
The study could help improve projections of future drought, allowing for more effective planning.
These traveling droughts also tend to be the largest and most severe ones, with the highest potential for damage to the agriculture, energy, water, and humanitarian aid sectors.
"Most people think of a drought as a local or regional problem, but some intense droughts actually migrate, like a slow-motion hurricane on a timescale of months to years instead of days to weeks," says Julio Herrera-Estrada, a graduate student in civil and environmental engineering at Princeton, who led the study.
The researchers analyzed drought data from 1979 to 2009, identifying 1,420 droughts worldwide.
They found hotspots on each continent where a number of droughts had followed similar tracks.
What causes some droughts to travel remains unclear, but the data suggest that feedback between precipitation and evaporation in the atmosphere and land may play a role.
"This study also suggests that there might be specific tipping points in how large and how intense a drought is, beyond which it will carry on growing and intensifying," said Justin Sheffield, a professor of hydrology and remote sensing at the University of Southampton.
Sheffield was Herrera-Estrada’s advisor while serving as research scholar at Princeton.