DYNAMIC COUPLING OF HYDROLOGICAL AND ATMOSPHERIC ...

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XVI International Conference on Computational Methods in Water Resources (CMWR-XVI) Ingeniørhuset

DYNAMIC COUPLING OF HYDROLOGICAL AND ATMOSPHERIC MODELS TO EXAMINE FEEDBACK EFFECTS
Paper
Author:Jesper Overgaard <jov@dhi.dk> (DHI - Water & Environment)
Michael B. Butts <mib@dhi.dk> (DHI - Water & Environment)
Dan Rosbjerg <dr@er.dtu.dk> (Environment & Resources - Technical University of Denmark)
Presenter:Michael B. Butts <mib@dhi.dk> (DHI - Water & Environment)
Date: 2006-06-18     Track: Special Sessions     Session: Field measurements and simulations of land-atmosphere interaction
DOI:10.4122/1.1000000559
DOI:10.4122/1.1000000560

Understanding the interaction between terrestrial microclimate, hydrology and ecology is a key to determining the effect of land-use and climate change on hydrological systems. Traditionally, the hydrological impacts of climate change have been based on driving hydrological models with the output of regional climate models. These climate models often operate at spatial and temporal scales that are much larger than the scales required to analyse the effects on the hydrological system. This is in part because of computational limitations and in part because of the physics of the regional models do not justify much higher resolution. Furthermore there is an inherent contradiction in this approach since these climate models include their own hydrological model component. Similarly in analysing the hydrological effects of land-use change the feedback to the meteorological system is often neglected. To address these issues a dynamically coupled hydrological and meteorological model system has been developed for evaluating interactions at hydrological (catchment) scales. Such a coupled system provides a unique framework for investigation of land surface - atmosphere interactions at hydrological scales. A comprehensive hydrological modelling system describing the terrestrial component of the hydrological cycle MIKE SHE has been modified to allow coupling to a local scale meteorological model. The coupling exploits the European Open Modelling Interface and Environment (OpenMI) Open MI to link the two models systems. As simulations can be run with and without coupling to the meteorological model, it is possible to evaluate the impact of feedbacks between the two systems on hydrological predictions. The uncoupled system has been validated against remote sensing and eddy correlation measurements at the field and landscape scale describing the hydrological and energy fluxes on the land-surface. The coupled system is then validated against field data describing both the atmosphere and hydrological system. Finally, a sensitivity analysis is carried out to examine the sensitivity of hydrological predictions to atmospheric feedbacks to identify where feedback will significantly affect the simulated impact.