Using Flux Data at a Range of Time-scales to Characterise the Role of the Land Surface in Evapotranspiration

Abstract:

Flux data gives information at a range of scales: from hourly to interannual (and in some cases decadal).

By analysing different timescales and using some different sampling strategies, it is possible to diagnose different aspects of the land surface that affect the energy partition into sensible and latent heat (evapotranspiration).

For instance, the night to day time ratio tells us about the aerodynamic roughness of the surface, the seasonality of the partition tells us about the phenology of the vegetation and the speed of dry down after a rainfall event tells us about the sizes of the stores of moisture both held within the canopy of the vegetation and in the root zone below the ground.

This study analyses a range of flux data at sites across the world in varying climate conditions, with carrying land cover attributes: trees, grasses and crops, deciduous and evergreen, broadleaf and needleleaf. The method designed to characterise the surface’s control of the evapotranspiration is quantified.

Ultimately the data is needed for model validation. In this case, the characterisation of the surface is used to inform a land surface model (JULES) which is used in global climate, weather and water resource applications.