Understanding water and energy fluxes in the Amazonia: Lessons from an observation-model intercomparison

Area of Science:

• Earth and Environmental Sciences
• Atmospheric Science
• Ecology

Background:

• Tropical forests significantly influence global water and energy cycles.
• Modeling the seasonality of land-atmosphere exchanges in these forests remains challenging.

Purpose of the Study:

• To report seasonality of heat fluxes and radiation at four Amazonian tropical forest sites.
• To investigate vegetation and climate impacts on these fluxes.
• To evaluate land surface model performance against observations.

Main Methods:

• Measured fluxes of latent heat (LE), sensible heat (H), and radiation at four diverse Amazonian sites.
• Analyzed the influence of vegetation and climate on observed fluxes.
• Compared land surface model simulations with observational data.

Main Results:

• Models inaccurately simulated dry-season evapotranspiration (ET) increases, overestimating Bowen ratios and vegetation temperatures.
• Models showed discrepancies in canopy emissivity and reflectance (albedo).
• These model-observation discrepancies biased seasonal estimates of net radiation (Rn), affecting LE and H simulations.

Conclusions:

• Improved representation of phenology-related parameters (leaf optical properties, canopy interception, skin temperature) is crucial.
• Enhancements can improve simulations of vegetation-atmosphere exchange.
• This will reduce uncertainty in regional and global biogeochemical models.