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| Titel |
Impact analysis of climate change for an Alpine catchment using high resolution dynamic downscaling of ECHAM4 time slices |
| VerfasserIn |
H. Kunstmann, K. Schneider, R. Forkel, R. Knoche |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
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| Erschienen |
In: Hydrology and Earth System Sciences ; 8, no. 6 ; Nr. 8, no. 6, S.1031-1045 |
| Datensatznummer |
250005991
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| Publikation (Nr.) |
 copernicus.org/hess-8-1031-2004.pdf |
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| Zusammenfassung |
| Global climate change affects spatial and temporal patterns of precipitation and so has a major impact on surface
and subsurface water balances. While global climate models are designed to describe climate change on global or continental scales, their
resolution is too coarse for them to be suitable for describing regional climate change. Therefore, regional climate models are applied to
downscale the coarse meteorological fields to a much higher spatial resolution to take account of regional climate phenomena. The changes
of atmospheric state due to regional climate change must be translated into surface and sub-surface water fluxes so that the impact on water
balances in specific catchments can be investigated. This can be achieved by the coupled regional climatic/hydrological simulations presented
here. The non-hydrostatic regional climate model MCCM was used for dynamic downscaling for two time slices of a global climate model
simulation with the GCM ECHAM4 (IPCC scenario IS92a, "business as usual") from 2.8° × 2.8° to 4 × 4 km2 resolution for the years 1991–1999
and 2031–2039. This allowed derivation of detailed maps showing changes in precipitation and temperature in a region of southern Germany and
the central Alps. The performance of the downscaled ECHAM4 to reproduce the seasonality of precipitation in central Europe for the recent
climate was investigated by comparison with dynamically downscaled ECMWF reanalyses in 20 × 20 km2 resolution. The downscaled ECHAM4 fields
underestimate precipitation significantly in summer. The ratio of mean monthly downscaled ECHAM4 and ECMWF precipitation showed little
variation, so it was used to adjust the course of precipitation for the ECHAM4/MCCM fields before it was applied in the hydrological model.
The high resolution meteorological fields were aggregated to 8-hour time steps and applied to the distributed hydrological model WaSiM to
simulate the water balance of the alpine catchment of the river Ammer (c. 700 km2) at 100 × 100 m2 resolution. To check the reliability of
the coupled regional climatic/hydrological simulation results for the recent climate, they were compared with those of a station-based
hydrological simulation for the period 1991–1999. This study shows the changes in the temperature and precipitation distributions in the
catchment from the recent climate to the future climate scenario and how these will affect the frequency distribution of runoff.
Keywords: coupled climate-hydrology simulations, dynamic downscaling, distributed hydrological modelling, ECHAM4 climate scenario, alpine hydrology |
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