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| Titel |
Bias Adjusted Precipitation Threat Scores |
| VerfasserIn |
F. Mesinger |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7340
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| Digitales Dokument |
URL |
| Erschienen |
In: Observation, Prediction and Verification of Precipitation (EGU Session 2007) ; Nr. 16 (2008-04-09), S.137-142 |
| Datensatznummer |
250013081
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| Publikation (Nr.) |
 copernicus.org/adgeo-16-137-2008.pdf |
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| Zusammenfassung |
Among the wide variety of performance measures available
for the assessment of skill of deterministic precipitation forecasts, the
equitable threat score (ETS) might well be the one used most frequently. It
is typically used in conjunction with the bias score. However, apart from
its mathematical definition the meaning of the ETS is not clear. It has been
pointed out (Mason, 1989; Hamill, 1999) that forecasts with a larger bias
tend to have a higher ETS. Even so, the present author has not seen this
having been accounted for in any of numerous papers that in recent years
have used the ETS along with bias "as a measure of forecast accuracy".
A method to adjust the threat score (TS) or the ETS so as to arrive at their
values that correspond to unit bias in order to show the model's or
forecaster's accuracy in \textit{placing} precipitation has been proposed earlier by the
present author (Mesinger and Brill, the so-called dH/dF method). A serious
deficiency however has since been noted with the dH/dF method in that the
hypothetical function that it arrives at to interpolate or extrapolate the
observed value of hits to unit bias can have values of hits greater than
forecast when the forecast area tends to zero. Another method is proposed
here based on the assumption that the increase in hits per unit increase in
false alarms is proportional to the yet unhit area. This new method removes
the deficiency of the dH/dF method. Examples of its performance for 12 months of
forecasts by three NCEP operational models are given. |
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