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| Titel |
Downscaling of surface moisture flux and precipitation in the Ebro Valley (Spain) using analogues and analogues followed by random forests and multiple linear regression |
| VerfasserIn |
G. Ibarra-Berastegi, J. Saénz, A. Ezcurra, A. Elías, J. Diaz Argandoña, I. Errasti |
| 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 ; 15, no. 6 ; Nr. 15, no. 6 (2011-06-21), S.1895-1907 |
| Datensatznummer |
250012858
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| Publikation (Nr.) |
 copernicus.org/hess-15-1895-2011.pdf |
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| Zusammenfassung |
| In this paper, reanalysis fields from the ECMWF have been statistically
downscaled to predict from large-scale atmospheric fields, surface moisture
flux and daily precipitation at two observatories (Zaragoza and Tortosa,
Ebro Valley, Spain) during the 1961–2001 period. Three types of downscaling
models have been built: (i) analogues, (ii) analogues followed by random
forests and (iii) analogues followed by multiple linear regression. The
inputs consist of data (predictor fields) taken from the ERA-40 reanalysis.
The predicted fields are precipitation and surface moisture flux as measured
at the two observatories. With the aim to reduce the dimensionality of the
problem, the ERA-40 fields have been decomposed using empirical orthogonal
functions. Available daily data has been divided into two parts: a training
period used to find a group of about 300 analogues to build the downscaling
model (1961–1996) and a test period (1997–2001), where models' performance
has been assessed using independent data. In the case of surface moisture
flux, the models based on analogues followed by random forests do not
clearly outperform those built on analogues plus multiple linear regression,
while simple averages calculated from the nearest analogues found in the
training period, yielded only slightly worse results. In the case of
precipitation, the three types of model performed equally. These results
suggest that most of the models' downscaling capabilities can be attributed
to the analogues-calculation stage. |
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