Turbulent transport within plant canopies

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Accurate measurements and predictions of turbulent dispersion of quantities such as heat, CO2 and particulates near the earth's surface are essential for a number of applications ranging from studies of the terrestrial energy and carbon budgets to effective air pollution control to anti-terrorism efforts. Theoretical descriptions of turbulent dispersion are posed in either Eulerian or Lagrangian frameworks. Field measurements are almost universally in the Eulerian framework out of practical necessity, and thus the literature using Eulerian descriptions is most prevalent. However, the Lagrangian framework is in many ways more theoretically satisfying and powerful, and a number of significant advances in Lagrangian theory and application have been made over the last two decades or so. Lagrangian theory is based on the statistical analysis of the paths ofmany diffusing particles; it is a 'particle-following' framework and therefore based on the total derivative. The power of the Lagrangian approach comes from this framework, however it also requires knowledge of turbulence statistics in the same framework. The overall focus of this research program is on improving our ability to determine the Lagrangian statistics and applying that knowledge to practical dispersion problems.