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 Basic Structure

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: Net Primary Productivity = NPP 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

Calibration-validation-application philosophy Calibration cycle Period Calibration data Validation data Applications 1 1995 – 1996 Previous LSX calibration Literature Vegetation patterns Large-scale runoff ISLSCP LAI Foley et al GBC 96 Costa & Foley JGR 97 2 1998 – 2000 Tower fluxes Soil moisture Idem NPP Soil C Delire & Foley JGR 99 Levis et al 99, 00 Kucharik et al GBC 00 Costa & Foley 00 Foley et al 00 Botta & Foley GBC 02 Coe et al JGR 02 Foley et al GBC 02 3 (current) 2002 – 2005 Multi-site tower fluxes On-site NPP MODIS products

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 1. Solar radiation/PAR balance 2. Net radiation balance 3. Night carbon fluxes 4. Latent/sensible/ground heat fluxes; daily carbon fluxes 5. Seasonal carbon allocation 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