Abstract ID: 647

Radiation and available water controls on modeled evapotranspiration seasonality across eight flux tower sites: Results from the LBA-MIP

One of the goals of recent syntheses of flux tower observations is to understand the dominant mechanisms controlling the seasonality of evapotranspiration (ET). These tower syntheses indicate a regionally varying relative importance of radiation and available water on ET. The LBA-Model Intercomparison Project (LBA-MIP) involves 10+ participating models and exists to gain comparative understanding of ecosystem models and to validate model predictions with flux tower datasets. All models were run at individual grid points corresponding to eight flux towers, parameterized using consistent surface datasets of soil properties and vegetation cover, and consistently driven using flux tower-derived gap-filled meteorological data. Here we place model results within the context of tower ET syntheses in order to identify concordance or disparity among model predictions and observations and to direct future research. We do so by using multiple regression of modeled ET first on driver variables of net radiation and precipitation, followed by model variables such as root zone soil moisture or soil wetness which are not routinely measured and are thus excluded from flux tower syntheses. In order to relate complex belowground hydrology schemes of models to available data, we in turn explore the degree to which empirical soil moisture bucket models concord with model predicted seasonal and interannual variability in vertically integrated soil moisture. Finally, we examine the model-predicted partitioning of ET into transpiration and evaporation components, and discuss the dominant model mechanisms responsible.

Session:  Carbon - The LBA Model-Intercomparison Project.

Presentation Type:  Oral