The term “drought” evokes pictures of scorched earth, dust-swept plains, depleted reservoirs, and dry stream beds caused by weeks or seasons of dry air.
In the sun-soaked Caribbean islands, drought conditions may develop quickly, with warning signals coming too late for mediation techniques to reduce crop losses or avoid stress on clean water infrastructure.
A new research by Assistant Professor Craig Ramseyer of the College of Natural Resources and Environment in the Journal of Hydrometeorology examines flash droughts. The report found that Caribbean Islands are more prone to unexpected droughts, and Ramseyer suggests using different methods to evaluate dry conditions.
“The tropics have extremely intense solar radiation, so atmospheric processes tend to be expedited,” stated geography professor Ramseyer. “Despite often receiving daily rainfall, island ecosystems are particularly vulnerable to drought conditions.”
Ramseyer, who studies tropical rainfall and severe weather in the Caribbean, used a novel drought index that incorporates atmospheric moisture demand instead of soil moisture data to determine drought risk.
“This new drought index is really developed to try to identify the first trigger of drought by focusing on evaporative demand,” said Ramseyer, who co-authored the article with Louisiana State University assistant professor Paul Miller. “Evaporative demand is a measure of how thirsty the atmosphere is and how much moisture it can collect from soil or plant matter.”
Ramseyer said early detection of drying conditions helps mitigate droughts.
“A lot of drought observation is based on soil moisture, but in tropical environments, a decline in soil moisture is a response to other things that have already happened so you’re further down in the chain of events,” stated. “We can mitigate a lot of losses in, say, agriculture, by being able to forecast sudden, anomalous increases in evaporative demand.”
Drought affects tropical ecosystems as well as agriculture, and communities and the Caribbean tourism industry depend on fresh water.
A new atmospheric research job
Ramseyer used 40 years of El Yunque National Forest ecological study data to better understand how weather patterns affect drought. He observed that flash droughts are common in the Caribbean and not restricted to dry seasons.
“In terms of climate, Puerto Rico is situated at a crossroads, buffered on the west by the El Niño southern oscillation and by the cooler North Atlantic oscillation on the east,” Ramseyer. “Because of that, Puerto Rico has a unique geography for researching atmospheric changes.”
Global warming concerns have increased the need for meteorologists to better understand Caribbean droughts and monitor moisture conditions.
“A warming planet results in more moisture available in the atmosphere overall, which means that the kinds of short-term precipitation events common to the Caribbean will increase in intensity,” Ramseyer. “Meanwhile, droughts are becoming higher in magnitude, so climate change is altering both extremes.”
Ramseyer, who helped Virginia Tech join the University Corporation for Atmospheric Research this year, said clearer flash drought criteria are a first step towards addressing Caribbean infrastructure issues.
“The key current and future issue for the Caribbean is all about finding a way to capture rainfall successfully and draw it out slowly to mitigate evaporation losses,” Ramseyer. “Puerto Rico and all of the Caribbean have water infrastructure challenges that must be addressed to accommodate these trends.”
Geography department head Tom Crawford said Ramseyer’s work uses big data to address climatic and meteorological issues.
“Dr. Ramseyer’s research applies advanced computing and geospatial science to make significant contributions to the problem of flash droughts and precipitation variability broadly,” he stated. “In addition to his research impact, his course on Climate Data Analysis and Programming is training the next generation of researchers on cutting edge computational techniques applied to the changing climate.”
Ramseyer recommends further study on flash droughts and economic losses and how to properly inform stakeholders and communities.
