Calibration and Validation of the Integrated Biosphere Simulator (IBIS) for a Brazilian Semiarid Region

The reliability of predictions from climate and weather models is linked to an adequate representation of the land surface processes. To evaluate performance and to improve predictions, land surface models are calibrated against observed data. Despite an extensive literature describing methods of la...

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Bibliographic Details
Published in:Journal of applied meteorology and climatology 2013-12, Vol.52 (12), p.2753-2770
Main Authors: Cunha, Ana Paula M. A., Alvalá, Regina C. S., Sampaio, Gilvan, Shimizu, Marília Harumi, Costa, Marcos Heil
Format: Article
Language:English
Subjects:
Agricultural research
Atmosphere
Atmospheric models
Biosphere
Brazil
Caatinga
Calibration
Climate and weather
Climate change
Climate models
Climate prediction
Climatology. Bioclimatology. Climate change
Computer simulation
Dry seasons
Earth, ocean, space
Ecosystem models
Ecosystems
Energy balance
Exact sciences and technology
External geophysics
Fluxes
General circulation models
Geophysics. Techniques, methods, instrumentation and models
Heat
Heat flux
Heat transfer
Humidity
Hydrology
Land
Land surface models
Latent heat
Latent heat flux
Mathematical models
Meteorology
Methods
Modeling
Modelling
Morphology
Natural vegetation
Optimization
Optimization techniques
Parameters
Parametric models
Performance evaluation
Physics
Physiology
Precipitation
Radiation
Rainy seasons
Semi arid areas
Semiarid lands
Semiarid zones
Sensible and latent heat
Simulation
Simulations
Simulators
Studies
Temperature
Vegetation
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Summary:The reliability of predictions from climate and weather models is linked to an adequate representation of the land surface processes. To evaluate performance and to improve predictions, land surface models are calibrated against observed data. Despite an extensive literature describing methods of land surface model calibration, few studies have applied a calibration method for semiarid natural vegetation, especially for the semiarid northeast of Brazil, which presents caatinga as its natural vegetation. Caatinga is a highly dynamic ecosystem with the physics at the land surface–atmosphere interface still poorly understood. Therefore, in this study a multi-objective hierarchical method, which provides means to estimate optimal values of the model parameters through calibration, is evaluated. This method is applied to caatinga by using the Integrated Biosphere Simulator (IBIS). Results demonstrated that the calibrated set of vegetation parameters produced a considerably different energy balance fromthe default parameters. In general, themodelwas able to simulate the partition of the available energy into sensible and latent heat fluxes when the calibrated parameters were used. The IBIS model was not able to capture short-term, intense changes in latent heat flux from a dry condition to a wetter condition, however, even when the new set of calibrated parameters was used. Therefore, the parameter optimization may not be sufficient if processes are missing or misrepresented. This study is one of the first to understand the physics at the land surface–atmosphere interface in the caatinga ecosystem and to evaluate the ability of the IBIS model to represent the biophysical interactions in this important ecosystem.
ISSN:1558-8424
1558-8432
DOI:10.1175/JAMC-D-12-0190.1