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| Titel |
On the uncertainties associated with using gridded rainfall data as a proxy for observed |
| VerfasserIn |
C. R. Tozer, A. S. Kiem, D. C. Verdon-Kidd |
| 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 ; 16, no. 5 ; Nr. 16, no. 5 (2012-05-23), S.1481-1499 |
| Datensatznummer |
250013301
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| Publikation (Nr.) |
 copernicus.org/hess-16-1481-2012.pdf |
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| Zusammenfassung |
| Gridded rainfall datasets are used in many hydrological and climatological
studies, in Australia and elsewhere, including for hydroclimatic
forecasting, climate attribution studies and climate model performance
assessments. The attraction of the spatial coverage provided by gridded data
is clear, particularly in Australia where the spatial and temporal
resolution of the rainfall gauge network is sparse. However, the question
that must be asked is whether it is suitable to use gridded data as a proxy
for observed point data, given that gridded data is inherently "smoothed"
and may not necessarily capture the temporal and spatial variability of
Australian rainfall which leads to hydroclimatic extremes (i.e. droughts,
floods). This study investigates this question through a statistical
analysis of three monthly gridded Australian rainfall datasets – the Bureau
of Meteorology (BOM) dataset, the Australian Water Availability Project
(AWAP) and the SILO dataset. The results of the monthly, seasonal and annual
comparisons show that not only are the three gridded datasets different
relative to each other, there are also marked differences between the
gridded rainfall data and the rainfall observed at gauges within the
corresponding grids – particularly for extremely wet or extremely dry
conditions. Also important is that the differences observed appear to be
non-systematic. To demonstrate the hydrological implications of using
gridded data as a proxy for gauged data, a rainfall-runoff model is applied
to one catchment in South Australia initially using gauged data as the
source of rainfall input and then gridded rainfall data. The results
indicate a markedly different runoff response associated with each of the
different sources of rainfall data. It should be noted that this study does
not seek to identify which gridded dataset is the "best" for Australia, as
each gridded data source has its pros and cons, as does gauged data. Rather,
the intention is to quantify differences between various gridded data
sources and how they compare with gauged data so that these differences can
be considered and accounted for in studies that utilise these gridded
datasets. Ultimately, if key decisions are going to be based on the outputs
of models that use gridded data, an estimate (or at least an understanding)
of the uncertainties relating to the assumptions made in the development of
gridded data and how that gridded data compares with reality should be made. |
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