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The Integrated Biosphere Simulator (IBIS) Basic structure and applications in Amazonia. Marcos Heil Costa Universidade Federal de Viçosa Regional Amazon Forest Structure and Carbon Cycling Workshop Tulane University, New Orleans, May 2004. IBIS Philosophy.
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The Integrated Biosphere Simulator (IBIS)Basic structure and applications in Amazonia Marcos Heil Costa Universidade Federal de Viçosa Regional Amazon Forest Structure and Carbon Cycling Workshop Tulane University, New Orleans, May 2004
IBIS Philosophy • Integrate in a single framework biophysical processes, plant biogeography, and carbon cycle • Must be compatible with a climate model • Must be rigorous with respect to physical laws (conservation of mass and energy) • Must have "hooks" to "hang" additional components in the future
IBIS Formulations • GCM-grade canopy physics: • Solar & Infrared radiative transfer • Diffusive & turbulent fluxes of heat and water vapor through canopy and soils (including soil ice) • Wind speeds through the canopy • Interception of rainfall and snow
IBIS Formulations • State-of-the-art canopy physiology: • Mechanistic photosynthesis (Farquhar et al.) • Semi-mechanistic stomatal conductance (Ball & Berry) • Coupled photosynthesis-stomatal conductance model (Collatz et al.) • coupled flow of carbon & water • Canopy scaling
IBIS Formulations • Canopy phenology: • Budburst and leaf fall of winter-deciduous plants based on climatic limits • Drought deciduous plants respond to net canopy carbon budget
IBIS Formulations • Vegetation dynamics: • 12 Plant Functional Types (PFTs: 8 in upper canopy, and 4 in lower canopy) • Compete for light & water • Competition is a consequence of the annual carbon balance
IBIS Formulations • Soil biogeochemistry: • CENTURY-like model • Active microbial pool • Net Primary Productivity = NPP NPP = GPP – Autotrophic Respiration (RA) • Net Ecosystem Exchange = NEE NEE = NPP – Heterotrophic Respiration (RH)
Calibration-validation-application philosophy • Quality of model results is proportional to the quantity, quality and independence of the data used during model calibration and validation • The larger the number of output variables calibrated, the more confidence we have in the model results
Calibration-validation-application philosophy New data becomes available Calibration Validation Application
Current (or next) calibration cycle We are looking for new opportunities/ collaborations to improve model calibration and validation Glad to be here!
Current calibration cycle (Amazon only) • Iterative hierarchical calibration • Calibrate the faster processes first, then the slower • Iterate until satisfactory • Use several tower sites for the same biome Calibrate in this order
Current efforts in LBA • Use newly produced LBA data to improve model credibility • Simulate effects of deforestation and rising CO2 concentration on the Amazon climate and feedbacks on forest structure, considering • biophysical effects (exchange of mass & energy) • physiological effects • biogeochemical feedbacks through atmospheric CO2 concentrations • Couple IBIS to a river biogeochemistry model and close the terrestrial/fluvial/atmospheric carbon cycle