Modeling feedbacks between a boreal forest and the planetary boundary layer

T. C. Hill, M. Williams, J. B. Moncrieff

    Research output: Contribution to journalArticlepeer-review

    12 Citations (Scopus)

    Abstract

    The atmosphere and biosphere interact strongly in the planetary boundary layer. Understanding the mechanisms controlling the coupled atmosphere-biosphere system allows improved scaling between observations at the stand scale ( e. g., flux towers) and those at larger scales, e. g., airborne or satellite measurements. Simulation of the joint atmosphere-biosphere system permits the study of feedbacks occurring within the coupled system. In this paper, two well-tested models, one a process-based biosphere model ( SPA) and the other a planetary boundary layer model ( CAPS), were coupled to allow simulation of atmosphere-biosphere feedbacks and interactions with a focus on ecological controls. As part of the validation process, the biosphere model was tested using eddy covariance, surface meteorology, and soil data collected during a 120 day period at a boreal black spruce site during the 1994 BOREAS field campaign. The coupled atmosphere-biosphere model was also validated with radiosonde data above the black spruce site, demonstrating that atmosphere and biosphere models can be coherently combined. We show that negative feedbacks at the black spruce site have strong moderating effects. The feedbacks reduce the mean impact of LAI changes on the atmospheric surface layer by 21% for latent energy, 64% for air temperature, and 44% for water mixing ratio. We show that both radiative and hydraulic limitations imposed by the vegetation structure strongly affected the interactions within the atmosphere-biosphere system, while the impact of the canopy roughness length was weak.

    Original languageEnglish
    Article numberD15122
    Pages (from-to)-
    Number of pages15
    JournalJournal of Geophysical Research
    Volume113
    DOIs
    Publication statusPublished - 12 Aug 2008

    Keywords

    • Surface parameterization schemes
    • Land-surface
    • Black spruce
    • Stomatal conductance
    • Hydraulic-properties
    • Flux measurements
    • Eddy covariance
    • Climate-change
    • Water-balance
    • Canopy

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