NSF grant will improve understanding of heat and gas exchange near Earth’s surface

Washington State University researchers have received a three-year National Science Foundation grant to make fundamental atmospheric measurements to better understand atmospheric processes near Earth's surface.

The work to study the exchange of heat, water vapor, and warming greenhouse gases could help improve climate and weather models.

"The idea has been in my mind for a while because this is kind of a fundamental question in micrometeorology and boundary-layer meteorology," said Heping Liu, professor in WSU's Department of Civil and Environmental Engineering who is leading the work.

The researchers are studying how heat and gases are transported in the earth's atmospheric boundary layer, which is the part of the atmosphere that is closest to the ground, extending from the surface up to several kilometers. During the day and when it's warm, air rises, and the boundary layer is usually thicker. At night and when it's cool, air sinks, and the boundary layer gets thinner. Strong winds mix up the air, which causes the boundary layer to expand to allow these quantities to be mixed within a larger space.

Climate and weather models assume that heat and gases move through the lower part of this layer in a rate that doesn't change with height, but many factors such as the complexity of Earth's surface and its constantly changing atmospheric conditions right above the surface can cause a varying rate. Models could be underestimating or overestimating how much heat and gases are moving from the surface into the atmosphere or how much is being returned to the surface.

""It is critical to know the rate since it determines how fast the atmosphere is warmed up and moistened," said Liu. "All models are built on this assumption, so, this is quite a critical part for models to get this flux. This project will allow me to dig into detail from the measurement side."

As part of the grant, the researchers will get detailed information of how the heat and gases are moving up into the atmosphere and back down to the surface, using sophisticated instrumentation to quantify the surface and land interaction. The researchers are setting up the instrumentation on a tower platform in a lake to study how atmospheric processes influence such an interaction. The lake is a good site for the work because it's flat and homogenous, eliminating other factors that could influence the way the heat and gases move with height.

"By analyzing the data and using some sophisticated data analysis tools, we can figure out how different turbulent processes contribute to the variations across different layers," said Liu.

In a separate Department of Energy project, Liu will study how the exchange of gases, heat, and other atmospheric constituents above forests might influence thunderstorm cloud formation.