Energy-based land-surface modelling: New opportunities in integrated hydrological modelling

Jesper Overgaard

Research output: Book/ReportPh.D. thesisResearch

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Abstract

The aim of this project is to identify and explore some of the new opportunities that arise from combining energy-based land-surface modelling and integrated hydrological modelling. Focus is on the improved possibilities for linking hydrological modelling, atmospheric modelling and remote sensing.

Initially, an energy-based two-layer land-surface model (LSM) was implemented in the integrated hydrological MIKE SHE model. The new land-surface model was evaluated against data comprising simultaneous measurements of all fluxes required to close the land-surface energy budget (net-radiation and latent, sensible and soil heat). The simulated fluxes were found to compare well to observations, despite significant differences in vegetation development stages and stress conditions in the four periods used in the evaluation.

A sensitivity experiment identified albedo, leaf area index and unstressed stomata resistance as the most important land-surface controls of total evapotranspiration. The largest sensitivities, however, were related to air temperature, air humidity and global radiation, stressing the importance of using climate data with a high quality as well as a high spatial and temporal resolution.

The new LSM permits the simulation of effective land-surface temperatures, which opens for a more efficient use of remote sensing for evaluation purposes. Remotely sensed land-surface temperatures have previously been used to qualitatively evaluate the spatial distribution of land-surface fluxes through a direct comparison of simulated and observed temperatures. This evaluation method is taken one step further here by proposing and testing a method to convert the differences between simulated and remotely sensed surface temperature into a corresponding difference in latent heat flux.

Finally, the energy-based LSM allows for a dynamical coupling between MIKE SHE and a meso-scale atmospheric model. Such a coupled model system will provide a unique framework for investigation of land surface-atmosphere interactions at hydrological scales. The development of such a system is described in detail with a focus on the interface between the two models, and the developed system is evaluated against both land surface and atmospheric observations. Finally, it is being used to investigate the significance of feedback in hydrological impact assessment studies.
Original languageEnglish
Place of PublicationKgs. Lyngby
PublisherDTU Environment
Number of pages31
ISBN (Print)87-89220-98-6
Publication statusPublished - Jun 2005

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