NMSU scientists use satellites to track massive dust storms
by Norman Martin
The huge dust storm, which appeared headed toward El Paso, and possibly the Midwest, intensified as it swept out of northern Mexico with winds reaching 60 miles per hour. Massive, choking plumes extended across the flat Chihuahuan Desert landscape for 200 miles.
“If you were standing in the middle of that storm, you would hardly be able to see your hand in front of your face,” said Max Bleiweiss, an NMSU research specialist.
Luckily, Bleiweiss, rail-thin and softspoken in a starched blue buttoned-down shirt, was standing in a calm, quiet secondstory computer laboratory in the Skeen Hall building, watching the brewing storm gather strength from an altitude of 22,000 miles. That’s where the government satellites are, shooting a stream of high resolution digital images back to earth and eventually NMSU.
Dust storms don’t show up on most weather tracking equipment, but they’re distinct on satellite images, where they look like feathery white blobs. “Dust from a storm like this can make it from New Mexico all the way to Canada,” he said. “Over long periods of time as this dust travels around, it changes the nature of soils it lands in, and dust in the atmosphere also has impacts on climate and weather.”
The big storm on the lab’s flat panel monitor was just one of more than 50 huge, rolling walls of dust the NMSU team has tracked in the past four years using satellite technology. Information is supplied from two polar orbiting weather satellites and the National Oceanic and Atmospheric Administration’s GOES-10 geostationary weather satellite.
Most of the storms are born in northern Mexico or southwestern New Mexico and die on the Midwestern plains. The storms trail thick, long plumes of dust that are soon swept into the upper atmosphere where the particles can ride for thousands of miles.
After tracking dozens of major dust storms, the scientists have found a common thread running through the weather events: a common birthplace or point source. The largest storms probably don’t come from a single point source, said Robert Sanderson, an associate professor at NMSU and expert in geographic information systems. Some of the large plumes probably originate from several locations and merge together as they move across the countryside, he said.
“They seem to be coming from very small regions, primarily in northern Mexico,” Sanderson said. “There are other point source areas, too, in southwestern New Mexico and southern Arizona.”
Many people think that dust storms come from large, dry lake beds, and sometimes that’s true, Bleiweiss added. But it looks like a lot of them actually come from much smaller areas – less than a square kilometer in size. “I think actually many of them are coming from fallow farm land,” he said. “And if they are, maybe we can use certain grasses or find other ways to slow them down or minimize them.”
So far, the NMSU researchers have just cataloged these point sources, seeking trends and additional ground data from highresolution satellites that can zoom in to a tenth of a mile. Next step is collaborating with researchers at University of Texas-El Paso and Colorado State University to analyze the dust storms in more detail.
“Satellite-based images provide data that’s sometimes not available from groundbased monitoring stations, especially in remote locations where you wouldn’t get many measurements,” said Jennifer Hand, a research scientist at CSU’s Cooperative Institute for Research in the Atmosphere.
One goal is to set up a warning system for major dust events, Bleiweiss said. “You could have a computer look at the satellite feeds and look for certain thresholds of white in a certain-sized region,” he said. “If it found it, it could automatically notify the weather service or traffic agency so they could send out a warning.”
Such tracking abilities could give people a few hours’ heads-up about a storm, Bleiweiss said. Dust storms cause all sorts of traffic problems, breathing problems, and there’s even an illness called valley fever associated with some aspects of them.
Typically, a dust storm is the result of convection currents created by intense heating of the ground. The air over the sand becomes hot, and rises. This creates differences in air pressure and temperature, and the cooler winds begin to rush in. Grains of sand tossed into the air by the wind usually fall after a few hours. Smaller particles stay in the air for a week or longer.
Severe storms can blow away topsoil, and reduce visibility to zero, making travel dangerous, said William Lindemann, an NMSU soil scientist. “Rows of trees, known as field windbreaks, can help reduce wind speed, wind erosion and damage to crops from wind-blown soil,” he said. But controlling the effects of a major dust storm is very difficult he said.
Still, there are smaller-scale solutions for high-traffic locations. Earlier this year state workers plowed up 300 acres of barren, private land along Interstate 40 between Milan and Grants and sprayed the soil with a sealant to reduce blowing dust. Plowing the soil mixes the lighter, sandy top layer with heavier soil and the sealant works to form a crust on the soil to keep it from blowing away.
In the past, state police have had to close the road several times due to low visibility from dust. Three people died in 2004 along the stretch of highway in accidents caused by severe dust storms.
Back in the university computer lab, Bleiweiss nodded toward the computer monitor and its satellite image. “I think probably the best we’ll ever be able to do is forecast these events the way we forecast the weather,” he said. “But maybe if we understand them more, we can also do more to stop them.”