1. 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

2. 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

3. IBIS Basic Structure

5. 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

6. 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

7. 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

8. 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

9. 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)

10. 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

11. Calibration-validation-application philosophy
New data becomes available
Calibration
Validation
Application

12. 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

13. Current (or next) calibration cycle
We are looking for new opportunities/ collaborations to improve model calibration and validation
Glad to be here!

14. 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

15. 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