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| Titel |
Up-scaling short-term process-level understanding to longer timescales using a covariance-based approach |
| VerfasserIn |
W. H. Lim, M. L. Roderick |
| 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 ; 18, no. 1 ; Nr. 18, no. 1 (2014-01-06), S.31-45 |
| Datensatznummer |
250120243
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| Publikation (Nr.) |
 copernicus.org/hess-18-31-2014.pdf |
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| Zusammenfassung |
| General experience in hydrologic modelling suggests that the parameterisation
of a model changes over different time and space scales. As a result,
hydrologists often re-parameterise their models whenever different temporal
or spatial resolutions are required. Here, we investigate theoretical aspects
of this issue in a search for the cause(s) of the need for
re-parameterisations. Based on Taylor series expansion, we present a
mathematical approach for temporal up-scaling that involves covariance-based
corrections. We apply the theory using a unique database of half-hourly pan
evaporation measurements (comprising 237 days) and examine how the model
parameters change when integrating from half-hour to daily and then monthly
integration periods. We show that the model parameters change over different
integration periods because of changes in the covariance between the model
variables. In our model system, we find that the covariance-based correction
is highly variable from day to day but settles down to a reasonably constant
value over periods longer than about 15 days. The 15 days timescale is
likely to be specific to our model system, nonetheless the underlying
principle that there is a characteristic timescale for the covariance-based
scaling correction of a particular hydrologic process might be general. If
that proved true it would open up the possibility of systematically searching
for characteristic integration periods for the key covariance-based scaling
terms in other key hydrologic processes. That would in turn enable the
development of more generalised hydrologic closure scheme(s). |
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