Predicting the Severity of Thunderstorms

TRACER site Photo Courtesy of ARM User Facility

A team of atmospheric scientists from around the nation is working in Houston to understand if tiny specks of soot, dust, smoke and other particles suspended in Earth’s atmosphere impact the severity of thunderstorms. Knowing this may make weather forecasts more accurate and provide crucial data for improving predictions about how aerosols may affect Earth’s future climate.

C-BAND Precipitation Radar Photo Courtesy of ARM User Facility

With a humid subtropical climate, numerous isolated convective storms, and a range of industrial and natural aerosol sources, Houston is the perfect place for the study, which will provide detailed data on local air quality. As an extensive field study in a metropolitan area, the effort will give scientists a unique opportunity to explore the effects of industry, vehicle emissions and the built environment on weather and climate. Examples include dust, sea salt, particles emitted by diesel engines, soot from combustion processes at power plants and refineries, lots of urban road traffic, and even smoke from wildfires in California and Colorado.

“We’re a coastal environment, so it’s particularly challenging to forecast the weather,” said James Flynn, research associate professor in the University of Houston Department of Earth and Atmospheric Sciences in the College of Natural Sciences and Mathematics. “We have a lot of thunderstorms; we have pollution and some natural sources of fine particles.”

Working in close collaboration with researchers at the University of Houston, TRACER scientists from Brookhaven National Laboratory, Los Alamos National Laboratory, and other institutions will collect data on aerosols and atmospheric characteristics for a full year. The team will deploy a suite of instruments supplied and operated by the Department of Energy’s Atmospheric Radiation Measurement (ARM) facilities at four locations just outside the city.

Some research suggests that such aerosols can change the lifecycle of clouds, delaying the onset of precipitation. If that happens, as clouds grow, water droplets may get bigger. “And when they do fall, it’s a gully washer,” Flynn said.

Over the course of the year, the ARM team will also launch more than a thousand weather balloons carrying additional battery-powered sensors, called radiosondes, aloft. The balloons will travel through and above the clouds, to an altitude up to 17 kilometers (nearly 56,000 feet)—often making it to the stratosphere—sending additional data on temperature, humidity, pressure, and winds back to the research station below.

“We’ll use these ozone measurements to learn about air quality and how thunderstorms redistribute air between the surface and aloft,” Flynn said. Surface ozone is generated when chemicals emitted as part of automobile exhaust and industrial processes react with sunlight. So, when storms transport air from the surface upward through the atmosphere, the pollutant can serve as a tracer for TRACER. TRACER is funded through the Department of Energy’s Office of Science.

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