The Atmospheric Boundary Layer

The most rapid and greatest transports of energy, mass and momentum occur within the atmospheric layer extending from the ground surface to an altitude of about 1500 meters (daytime). This region of the atmosphere is the so called atmospheric boundary layer and its thermodynamics and kinematics undergo pronounced diurnal changes in response to the surface-atmosphere exchanges of energy, mass and momentum. During the last decade, collaborating with collagues such as Michael Garstang, Alan Betts and many others I have conducted feld campaigns to investigate (1) the dynamics of the atmospheric boundary layer and (2) the links between surface-based processes, such as evapotranspiration and ozone dynamics, with the deeper atmosphere. The field research has been achieved in places such as the Amazonia of Brazil, the Marshall Islands, the southern boreal region of Canada and the Canadian high Arctic. In all field campaigns, we have contributed with the development and deployment of state-of-the-art instrumentation on towers, tethered balloons, and "free balloons" to learn the rates of atmospheric turbulent transport of materials from the surface to the deeper atmosphere and vice versa. The purpose of this type of research is to investigate how much water vapor moves from the tropical continental and oceanic surfaces to the cloud sublayer. Some of this research is in support of NASA’s Tropical Rainfall Measuring Mission (TRMM) satellite. When water evaporates, large amounts of energy are needed. Most of the evaporated water rises to deep levels in the atmosphere, cools and condenses to form clouds. But as water condenses, the energy invested in evaporation is released back into the environment, thus warming the atmosphere. Because tropical clouds grow deep into the atmosphere (5-8 km), the energy released when water condenses is left behind. Due to the global circulation patterns of the Earth’s atmosphere, this energy can then be transported from tropical to extratropical regions. This is one manner in which the atmosphere can transport heat from energy-surplus to energy-deficit regions.  Our most current field projects are taking place in the Canadian high Arctic (at Alert, Nunavut, Canada), Senegal (west Africa), New Mexico, and the Piedmont of central Virginia.