Dr. Ari Preston’s Ph.D. Research on Tropical Cyclones and Atmospheric Chemistry

Dr. Aaron (Ari) Preston, Visiting Assistant Professor of Atmospheric Sciences, recently defended his Ph.D. research on the transport of chemical species to the upper troposphere/lower stratosphere (UTLS) by tropical cyclones. Species such as carbon monoxide, nitrogen oxide, and ozone have been found to exert a greater influence on climate change at these high altitudes than if remaining near the surface. Typhoon Mireille (1991) was examined in the western North Pacific Ocean basin using in situ aircraft-derived chemical data from NASA’s Pacific Exploratory Mission-West A field project.

WRF domains, best track, and simulation tracks
The three nested domains (black outlines) used in the coupled WRF-Chem simulation. From outer to inner, the domains have a grid spacing of 27 km (d01), 9 km (d02), and 3 km (d03). Black dots show the best track of Typhoon Mireille, while red dots show the track of the simulation

The Weather Research and Forecasting (WRF) model was used with chemistry (WRF-Chem) at an innermost grid spacing of 3 km. This grid spacing explicitly resolved the convection being studied. Results show that pollution from distant sources were ingested by Mireille and subsequently lofted by eyewall convection to the UTLS, enhancing concentrations in this region. Flux calculations suggested that a strong tropical cyclone, such as Mireille, can impact UTLS chemistry as much as a continental middle latitude cyclone. Furthermore, overshooting cells in Mireille produced chemical flux density values at the tropopause level as much as 10-20 times greater than that of the tropical cyclone as a whole. Thus, although the overshooting tops comprised only a small area of the total tropical cyclone, they transport large quantities of gaseous species to the UTLS because of their very strong updrafts. Results also suggested that millions of cars would need to be hypothetically placed in the upper troposphere to have the same impact on chemical concentrations as Mireille. This demonstrated the transport strength of the tropical cyclone as a whole.

Profiles of vertical flux from the surface to 27.5 km of various species from the 3 km domain at 0000 UTC 27 September. Values are color-coded by tropical cyclone region, and upward (downward) fluxes are denoted by thick (thin) dashed lines. The gray horizontal line represents the approximate height of the tropopause level.

Improved understanding of atmospheric chemistry in the western North Pacific basin is important, especially in the context of increasing Asian emissions and a changing climate. Furthermore, since it has been hypothesized that global warming will lead to more intense storms, it is important to understand tropical cyclones’ role in chemical transport.

Climate Change Communication Practice

Students in the Climate Change Communication group at Lyndon have many opportunities to practice communicating the science about climate change.

Most recently, on Wednesday, January 24, 2018, the Atmospheric Sciences department co-hosted an event, “2018 Acting on Climate Change in VT,” with the Vermont Natural Resources Council and Energy Independent Vermont. This event was held at the Kingdom Taproom in St. Johnsbury, VT.

Dr. Janel Hanrahan, Assistant Professor of Atmospheric Sciences at Lyndon, and two student members from Lyndon’s Climate Change Communication group, Jonathan Hutchinson and Francis Tarasiewicz, were three of several speakers at the event. This was an excellent opportunity for them to practice communicating about climate change science and to share their personal climate change stories.

Fall 2017 Climate Change Communication

Throughout the fall of 2017, Atmospheric Sciences and Climate Change Science students practiced informal communication skills in various settings.  They discussed climate change science with local middle and high school students at the Youth Environmental Summit and the Burke Community Fair, and presented fundamental climate change concepts at Springfield College. Some students took the initiative to visit their former high schools to stress the need for climate change action. In addition, the Climate Change Communication group hosted a campus-wide movie screening, attended a Vermont Climate Action Commission scoping meeting, and created new blog posts for www.theclimateconsensus.com.

Winter Weather: The Weird, The Wacky And The Wonderful

Snow devil in Vermont.

Our own Dr. Jay Shafer¬†was a guest on Vermont Public Radio’s Vermont Edition on January 22, 2018, along with the Vermont State Climatologist¬†Lesley-Ann Dupigny-Giroux. They answered listener questions about winter weather phenomena in Vermont, including:

Why does it get quieter when it snows?
Can there actually be thunder and lightning during a snow storm?
How can smog and flooding happen in the dead of winter?

Listen to the recording online at: http://digital.vpr.net/post/winter-weather-weird-wacky-and-wonderful