Investigating biosphere-atmosphere interactions from leaf to atmospheric boundary layer scales.

摘要

The interaction between terrestrial ecosystems and the atmosphere continues to be a central research topic within the climate, hydrology, and ecology communities. This interest is stimulated by research issues pertinent to the development of governing laws describing exchange of mass and energy and the hierarchy of space-time scales. Here, these biosphere-atmosphere interactions are considered at two different hierarchical scales: leaf-to-canopy scale and canopy-to-atmospheric boundary-layer (ABL) scale. Both models and long-term measurements collected from three adjacent ecosystems at Duke Forest AmeriFlux sites are employed.; For the leaf-to-canopy scale, two classical problems, motivated by contemporary applications, were considered: (1) the 'inverse problem'---an Eulerian inverse approach was developed to separate aboveground respiration from forest floor efflux using mean scalar profiles within the canopy and detailed turbulent transport theories; (2) the forward problem---a forward multilayer model is used in the evaluation of the two-way interactions between leaves and their microclimate at annual and inter-annual time scales. The complexity in the turbulent transport model (i.e. closure level) needed for resolving such two-way interactions between leaf and canopy was also analyzed.; For the canopy-to-ABL scale, this study mainly explored problems pertinent to the impact of ecophysiological controls on the regional environment. First, the possible combinations of water states (soil moisture and atmospheric humidity) that trigger convective rainfall were investigated, and a distinct 'envelope' of these combinations emerged from the measurements. Second, an analytical model as a function of atmospheric and ecophysiological properties was proposed to examine how the potential to trigger convective rainfall shifts over three different land-cover types. The results suggest that pine plantation, whose area is projected to dramatically increase in the Southeastern US (SE), has greater potential to trigger convective rainfall than the other two ecosystems considered here. Finally, the interplay between ecophysiological and radiative attributes on surface temperature, in the context of regional cooling/warming, was investigated for projected land-use scenarios in the SE region.