Investigating Biosphere-Atmosphere Interactions from Leaf to Atmospheric Boundary Layer Scales

by Juang, Jehn-Yih

Abstract (Summary)
The interaction between terrestrial ecosystems and the atmosphere continues to be

a central research theme within climate, hydrology, and ecology communities. This

interest is stimulated by research issues pertinent to both the fundamental laws and the

hierarchy of scales. To further explorer such topics over various spatial and temporal

domains, in this study, biosphere-atmosphere interactions are studied at two different

scales, leaf-to-canopy and canopy-to-atmospheric boundary-layer (ABL) scales, by

utilizing both models and long-term measurements collected from the Duke Forest

AmeriFlux sites.

For the leaf-to-canopy scale, two classical problems motivated by contemporary

applications are considered: (1) ‘inverse problem’ – determination of nighttime

ecosystem respiration, and (2) forward problem – estimation of two-way interactions

between leaves and their microclimate ‘’. An Eulerian inverse approach was developed to

separate aboveground respiration from forest floor efflux using mean CO2 concentration

and air temperature profiles within the canopy using detailed turbulent transport theories.

The forward approach started with the assumption that canopy physiological, drag, and

radiative properties are known. The complexity in the turbulent transport model needed

for resolving the two-way interactions was then explored. This analysis considered a

detailed multi-layer ecophysiological and radiative model embedded in a hierarchy of

Eulerian turbulent closure schemes ranging from well-mixed assumption to third order

closure schemes with local thermal-stratification within the canopy.

For the canopy-to-ABL scale, this study mainly explored problems pertinent to

the impact of the 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 different land-covers. 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. Finally, the interplay between ecophysiological and radiative attributes

on surface temperature, in the context of regional cooling/warming, was investigated for

projected land-use changes in the SE region.

Bibliographical Information:

Advisor:Katul, Gabriel; Oren, Ram; Kasibhatla, Prasad; Albertson, John; Porporato, Amilcare

School:Duke University

School Location:USA - North Carolina

Source Type:Master's Thesis

Keywords:terrestrial ecosystems duke forest ameriflux pine plantation southeastern us


Date of Publication:03/14/2007

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