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| Titel |
Structural and statistical properties of the collocation technique for error characterization |
| VerfasserIn |
S. Zwieback, K. Scipal, W. Dorigo, W. Wagner |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 19, no. 1 ; Nr. 19, no. 1 (2012-02-09), S.69-80 |
| Datensatznummer |
250014159
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| Publikation (Nr.) |
 copernicus.org/npg-19-69-2012.pdf |
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| Zusammenfassung |
| The validation of geophysical data sets (e.g. derived from models,
exploration techniques or remote sensing) presents a formidable challenge as
all products are inherently different and subject to errors. The collocation
technique permits the retrieval of the error variances of different data
sources without the need to specify one data set as a reference. In addition
calibration constants can be determined to account for biases and different
dynamic ranges. The method is frequently applied to the study and comparison
of remote sensing, in-situ and modelled data, particularly in hydrology and
oceanography. Previous studies have almost exclusively focussed on the
validation of three data sources; in this paper it is shown how the technique
generalizes to an arbitrary number of data sets. It turns out that only parts
of the covariance structure can be resolved by the collocation technique,
thus emphasizing the necessity of expert knowledge for the correct validation
of geophysical products. Furthermore the bias and error variance of the
estimators are derived with particular emphasis on the assumptions necessary
for establishing those characteristics. Important properties of the method,
such as the structural deficiencies, dependence of the accuracy on the number
of measurements and the impact of violated assumptions, are illustrated by
application to simulated data. |
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