The Answer is Blowing in Trent’s Wind (Tunnel)
Environmental Wind Tunnel Research Group at Trent is advancing our understanding of how particulate matter circulates in Earth’s atmosphere
When Eyjafjallajökull erupted, confusion ensued, and it wasn’t just among news anchors stumbling over their words as they struggled to pronounce the Icelandic volcano’s tricky name.
With ash suspended above the north Atlantic, pilots’ vision was obscured, aircraft glass melted, and jet engines clogged. Trans-Atlantic flights were grounded, and experts weren’t sure how long the disruption would last.
That’s in part because models of aeolian entrainment, transport and deposition – how particles are moved by wind and how long they remain suspended – were developed at more southerly latitudes for particles that have different characteristics than volcanic ash.
Using Trent’s wind tunnel to better understand atmospheric processes
Trent’s Dr. Cheryl McKenna-Neuman, a faculty member in the School of the Environment, is working to ensure this doesn’t happen again through her research to comprehend how aeolian transport is unique at more northerly latitudes. This research with Ph.D. candidate Tamar Richards-Thomas is just one of the ways that the Trent Environmental Wind Tunnel Research Group is helping us better understand and model these atmospheric processes.
“Volcanic ash is porous, light and really angular,” Professor McKenna-Neuman says. “It’s easily suspended. There’s a large amount of literature on the physics of its deposition for equatorial regions or low-latitude hot deserts, but little is known about these processes at higher latitudes. Low temperatures are the main difference, but the climate is comparatively humid, and the geology is different too.”
Trent’s wind tunnel is one of only a few facilities worldwide that’s devoted to particle transport. It can control temperature, wind speed and humidity to replicate conditions like Iceland’s.
Knowledge of how ash from Eyjafjallajökull is transported, deposited, and resuspended will enable better modeling of the impact of any future eruption.
“We have enough experimental control that we can simulate a complex process that occurs outdoors and is quite messy. It allows us to deconstruct what's happening,” explains Prof. McKenna-Neuman.
Researching ways to reduce amount of dust in the wind
Particles suspended in the air can impact more than air travel. Some forms of dust are associated with lung conditions like emphysema, so that tiny particles less than one-hundredth of a millimeter in size fall under air quality regulation.
In replicating the conditions of California’s Owens Lake, Prof. McKenna-Neuman’s lab group is exploring ways to reduce the amount of dust entrained in the wind.
The lake was drained to divert water to Los Angeles, leaving behind a dry, dusty lakebed. This diversion exposed Owens Lake to atmospheric processes.
“The finest particles in its sediment can be entrained in the wind and carried hundreds of kilometers. We’ve been looking at how wet the surface needs to be to trap those particles, and discovered that even small amounts of moisture can lock them in,” says Prof. McKenna-Neuman. “We don’t have a specific target moisture content because the lakebed surface has a highly varied texture and forms a crust when it dries, but our measurements confirm that it doesn’t need to be maintained in a state of continuous saturation to control emissions.”