Engineer wins prestigious NSF award

By Robert Emro, CEPS

If you spend time on the water, you may have noticed a curious phenomenon that is the subject of a UNH professor’s $472,000 National Science Foundation (NSF) grant.

Greg Chini

When the wind is blowing just right, foam and flotsam line up in long streaks, roughly pointing in the same direction as the wind. Sailors call them windrows, for they are reminiscent of fields of hay raked into rows to dry. But to Greg Chini, an assistant professor of mechanical engineering, they are evidence of something happening beneath the surface that scientists call Langmuir circulation.

An expert in fluid dynamics, Chini recently received a five-year NSF CAREER Award to study what role this little-understood phenomenon might play in the larger ocean. His research promises to improve weather forecasting and climate prediction.

First described by Irving Langmuir in 1938, Langmuir circulation is driven by the wind and consists of horizontal spirals of current. Adjacent spirals, or Langmuir cells, rotate in opposite directions and so create windrows by pushing anything floating on the surface into the spaces between them.

Langmuir circulation is important because it acts like a giant mixing machine in the top layer of the ocean – the interface between the atmosphere and the deep ocean. This “mixed layer” controls the exchange of heat and gases, such as CO2, the chief suspect in global warming. It extends to a depth of about 325 feet and, compared to deeper layers, is relatively uniform in temperature, salinity and density.

Chini will work with graduate and undergraduate students to determine how Langmuir circulation interacts with “internal waves” that travel just beneath the mixed layer, where temperatures drop sharply. Anyone who has felt the chilly water near the bottom while swimming in a lake is familiar with this layer, called the thermocline.

Chini is the second CEPS researcher in recent months to receive a CAREER Award – one of NSF’s most prestigious awards for new faculty members. Jo Daniel, assistant professor of civil engineering, was awarded a $400,000 NSF CAREER grant in December to study “viscoelastic” materials, such as asphalt.

The award recognizes and supports the early career-development activities of those teacher-scholars who are most likely to become the academic leaders of the 21st century. Awardees are selected on the basis of creative, career-development plans that effectively integrate research and education.

Five other CEPS faculty working on NSF CAREER grants, including Carmela Amato-Wierda, associate professor of material science; Karsten Pohl, assistant professor of physics; Elizabeth Varki, associate professor of computer science; Liming Ge, professor of math; and Robert Griffin, assistant professor of earth sciences.