Abstract
Abstract. In this study we evaluate a methodology for disaggregating land surface energy fluxes estimated with the Two-Source Energy Balance (TSEB)-based Dual-Temperature Difference (DTD) model which uses day and night polar orbiting satellite observations of land surface temperature (LST) as a remotely sensed input. The DTD model is run with MODIS input data at a spatial resolution of around 1 km while the disaggregation uses Landsat observations to produce fluxes at a nominal spatial resolution of 30 m. The higher-resolution modelled fluxes can be directly compared against eddy covariance (EC)-based flux tower measurements to ensure more accurate model validation and also provide a better visualization of the fluxes' spatial patterns in heterogeneous areas allowing for development of, for example, more efficient irrigation practices. The disaggregation technique is evaluated in an area covered by the Danish Hydrological Observatory (HOBE), in the west of the Jutland peninsula, and the modelled fluxes are compared against measurements from two flux towers: the first one in a heterogeneous agricultural landscape and the second one in a homogeneous conifer plantation. The results indicate that the coarse-resolution DTD fluxes disaggregated at Landsat scale have greatly improved accuracy as compared to high-resolution fluxes derived directly with Landsat data without the disaggregation. At the agricultural site the disaggregated fluxes display small bias and very high correlation (r ≈ 0.95) with EC-based measurements, while at the plantation site the results are encouraging but still with significant errors. In addition, we introduce a~modification to the DTD model by replacing the "parallel" configuration of the resistances to sensible heat exchange by the "series" configuration. The latter takes into account the in-canopy air temperature and substantially improves the accuracy of the DTD model.
Highlights
The reliable estimation of surface energy fluxes in agricultural landscapes requires that the model’s spatial resolution matches the dominant landscape feature scale (Kustas and Albertson, 2003; Kustas et al, 2004)
In this study we evaluate a methodology for disaggregating land surface energy fluxes estimated with the TwoSource Energy Balance (TSEB)-based Dual-Temperature Difference (DTD) model which uses day and night polar orbiting satellite observations of land surface temperature (LST) as a remotely sensed input
In many heterogeneous agricultural landscapes the field sizes can be of order of a couple of hectares, meaning that the spatial resolution of the LST satellite observation needs to be in the order of 100 m × 100 m
Summary
The reliable estimation of surface energy fluxes (latent heat – LE, sensible heat – H , ground heat – G, and net radiation – Rn) in agricultural landscapes requires that the model’s spatial resolution matches the dominant landscape feature scale (Kustas and Albertson, 2003; Kustas et al, 2004). In many heterogeneous agricultural landscapes the field sizes can be of order of a couple of hectares, meaning that the spatial resolution of the LST satellite observation needs to be in the order of 100 m × 100 m. There are a number of methodologies which can exploit the Landsat-derived LST for estimating surface energy fluxes. They range from empirical, like the triangle approach (Stisen et al, 2008), to more physically based, such as one-source energy balance (Bastiaanssen et al, 1998) or Published by Copernicus Publications on behalf of the European Geosciences Union
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
