Tropical rain forests represent some of the most diverse ecosystems on earth, yet mechanistic links between tree species identity and ecosystem function in these forests remains poorly understood. Here, using free-living nitrogen (N) fixation as a model, we explore the idea that interspecies variation in canopy nutrient concentrations may drive significant local-scale variation in biogeochemica...

The replacement of native vegetation for agriculture leads to significant changes in land surface characteristics, such as albedo, surface roughness and canopy resistance. These land surface changes induce changes in the atmospheric boundary layer. It is shown that in Western Australia, this change in surface characteristics and in particular, the albedo, has reduced the occurrence of convectiv...

Rainforests represent the epitome of structural complexity in terrestrial ecosystems. However, measures of three-dimensional canopy structure are limited to a few areas typically < 1 ha with construction crane or walkway/platform access. An innovative laser pro® ling system, the Laser Vegetation Imaging Sensor (LVIS), was used to map canopy structure (i.e. based on height and vertical distribut...

[1] Two characteristics that distinguish canopy sublayer (CSL) turbulence from its atmospheric surface layer (ASL) counterpart are short-circuiting of the energy cascade and formation of Kelvin-Helmholtz (KH) vortices near the canopy top. These two phenomena lead to nonlinear and poorly understood interactions between small and large scale eddies within the CSL absent from classical ASL turbule...

This thesis presents two distinct bodies of work concerning quadrotor flight in urban wind fields. The first attempts to characterize a quadrotor's ability to exploit urban wind fields for improved flight performance. A computational fluid dynamics model is used to obtain a wind field estimate given a 3D model of the environment and a prevailing wind estimate. Minimum-energy trajectories are th...

A generalization of the single soil layer variable infiltration capacity (VIC) land surface hydrological model previously implemented in the Geophysical Fluid Dynamics Laboratory general circulation model (GClVO is described. The new model is comprised of a two-layer characterization of the soil column, and uses an aerodynamic representation of the latent and sensible heat fluxes at the land su...