Sometimes kilometers wide and thousands of meters tall, dust storms look like massive, advancing walls of airborne dirt. They’re so thick and form so quickly that they can cut visibility to zero in under a minute. When dust storms strike highways, they make safe driving nearly impossible. These storms can even transport infectious pathogens, like the fungus responsible for valley fever.
Dust storms consist of fine, dry soil particles blown by strong winds, often generated by a thunderstorm. Four main factors for dust storm formation are wind, soil moisture, vegetation cover that can help hold soil in place, and seasonal temperatures. Human activity, like industrial development and agriculture, can also contribute to soil erosion and dusty conditions.
In the American Southwest, accurately predicting these storms has remained a challenge. Daniel Tong, an atmospheric scientist and associate professor at George Mason University, has been working to change that with a new satellite-aided dust forecasting system.
Predicting the Future
Current meteorological models, like those used by the National Weather Service, don’t work well for predicting dust storms in the relatively small region of the southwestern United States. Mariana Casal, division manager of the Pinal County Public Health Department in Arizona who has worked with Tong on dust-related public health projects, says current alert systems warn of dust storms only about an hour or two in advance.
“Predicting dust is very challenging. Models are not very good at predicting high winds, and you have to capture the precipitation right, which is also difficult to predict. And you have to get the surface conditions right,” said Tong. “It’s not easy.”
Tong and his team are trying to get everything right by using near-real-time satellite imagery. The satellite images can pick out surface conditions that breed dust storms so that forecasting models can incorporate data on active dust sources.
Providing early warnings could prevent traffic accidents and deaths. Dust storms cut visibility and coat roads in fine particles, making the surface slippery and creating dangerous driving conditions. Tong and his colleagues have looked at police records from the Department of Transportation’s Fatality Analysis Reporting System and estimate that dust storms led to traffic accidents that killed between 13 and 33 people each year between 2007 and 2017.
Having a better forecast, even alerting people of what to expect in the morning, afternoon, or night, would be helpful, said Casal. Such a forecast could help people better plan their travel and prevent them from driving right before dust storms.
“That region really needs this kind of work,” said Andrea Sealy, chair of the Pan-American Regional Steering Group of the World Meteorological Organization’s Sand and Dust Storm Warning Advisory and Assessment System. In the U.S. Southwest, not only can dust storms cause traffic accidents, but they also lower air quality and transport valley fever-causing fungus. “All of these have environmental health and economic consequences,” said Sealy.
The Future of Dust Forecasting
So far, Tong thinks the new technique, which he and his team will present at AGU’s Fall Meeting 2020, shows promise. “We are going to share the information with the National Weather Service so they can adopt the approach,” he said.
Tong’s team is also working with a citizen dust watch group to get forecasts into the hands of the public. This group consists of high school students working to develop cell phone apps that can warn users of dust storms. But most dust models use data inscrutable to nonexperts. “Our group developed a data service where we put the model’s data in our computers and we convert it into a readable format so that people can use our data to build their own apps,” said Tong.
Tong’s forecasting system, part of a larger project with the Applied Sciences program at NASA, will not only help reduce highway accidents but could also improve disease surveillance for valley fever and air quality management. “If we do things right,” said Tong, “then we can save people’s lives.”
—Jackie Rocheleau (@JackieRocheleau), Science Writer