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| Titel |
Analysis of aggregation and disaggregation effects for grid-based hydrological models and the development of improved precipitation disaggregation procedures for GCMs |
| VerfasserIn |
H. S. Wheater, T. J. Jolley, C. Onof, N. Mackay, R. E. Chandler |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 3, no. 1 ; Nr. 3, no. 1, S.95-108 |
| Datensatznummer |
250000758
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| Publikation (Nr.) |
 copernicus.org/hess-3-95-1999.pdf |
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| Zusammenfassung |
Appropriate representation of hydrological processes
within
atmospheric General Circulation Models (GCMs) is important with respect to internal model
dynamics (e.g. surface feedback effects on atmospheric fluxes, continental runoff
production) and to simulation of terrestrial impacts of climate change. However, at the
scale of a GCM grid-square, several methodological problems arise. Spatial disaggregation
of grid-square average climatological parameters is required in particular to produce
appropriate point intensities from average precipitation. Conversely, aggregation of land
surface heterogeneity is necessary for grid-scale or catchment scale application.
The
performance of grid-based hydrological models is evaluated for two large
(104km2)
UK catchments. Simple schemes, using sub-grid average of individual land use at 40 km
scale and with no calibration, perform well at the annual time-scale and, with the
addition of a (calibrated) routing component, at the daily and monthly time-scale.
Decoupling of hillslope and channel routing does not necessarily improve performance or
identifiability. Scale dependence is investigated through application of distribution
functions for rainfall and soil moisture at 100 km scale. The results depend on climate,
but show interdependence of the representation of sub-grid rainfall and soil moisture
distribution.
Rainfall distribution is analysed directly using radar rainfall data from
the UK and the Arkansas Red River, USA. Among other properties, the scale dependence of
spatial coverage upon radar pixel resolution and GCM grid-scale, as well as the serial
correlation of coverages are investigated. This leads to a revised methodology for GCM
application, as a simple extension of current procedures.
A new location-based approach
using an image processing technique is then presented, to allow for the preservation of
the spatial memory of the process. |
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