The benefits of spatial resolution increase in global simulations of the hydrological cycle evaluated for the Rhine and Mississippi basins
<p>To study the global hydrological cycle and its response to a changing climate, we rely on global climate models (GCMs) and global hydrological models (GHMs). The spatial resolution of these models is restricted by computational resources and therefore limits the processes and level of detai...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-04-01
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| Series: | Hydrology and Earth System Sciences |
| Online Access: | https://www.hydrol-earth-syst-sci.net/23/1779/2019/hess-23-1779-2019.pdf |
| Summary: | <p>To study the global hydrological cycle and its response to a
changing climate, we rely on global climate models (GCMs) and global
hydrological models (GHMs). The spatial resolution of these models is
restricted by computational resources and therefore limits the processes and
level of detail that can be resolved. Increase in computer power therefore
permits increase in resolution, but it is an open question where this
resolution is invested best: in the GCM or GHM. In this study, we evaluated
the benefits of increased resolution, without modifying the representation of
physical processes in the models. By doing so, we can evaluate the benefits
of resolution alone. We assess and compare the benefits of an increased
resolution for a GCM and a GHM for two basins with long observational
records: the Rhine and Mississippi basins. Increasing the resolution of a GCM
(1.125 to 0.25<span class="inline-formula"><sup>∘</sup></span>) results in an improved precipitation budget over the
Rhine basin, attributed to a more realistic large-scale circulation. These
improvements with increased resolution are not found for the Mississippi
basin, possibly because precipitation is strongly dependent on the
representation of still unresolved convective processes. Increasing the
resolution of the GCM improved the simulations of the monthly-averaged
discharge for the Rhine, but did not improve the representation of extreme
streamflow events. For the Mississippi basin, no substantial differences in
precipitation and discharge were found with the higher-resolution GCM
and GHM. Increasing the
resolution of parameters describing vegetation and orography in the
high-resolution GHM (from 0.5 to 0.05<span class="inline-formula"><sup>∘</sup></span>) shows no significant
differences in discharge for both basins. A straightforward resolution
increase in the GHM is thus most likely not the best method to improve
discharge predictions, which emphasizes the need for better representation of
processes and improved parameterizations that go hand in hand with resolution
increase in a GHM.</p> |
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| ISSN: | 1027-5606 1607-7938 |