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| Titel |
Probabilistic prediction of raw and BMA calibrated AEMET-SREPS: the 24 of January 2009 extreme wind event in Catalunya |
| VerfasserIn |
P. Escribà, A. Callado, D. Santos, C. Santos, J. A. García-Moya, J. Simarro |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7340
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| Digitales Dokument |
URL |
| Erschienen |
In: 11th EGU Plinius Conference on Mediterranean Storms (2009) ; Nr. 26 (2010-11-22), S.119-124 |
| Datensatznummer |
250015992
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| Publikation (Nr.) |
 copernicus.org/adgeo-26-119-2010.pdf |
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| Zusammenfassung |
At 00:00 UTC of 24 January 2009 (24Jan09) an explosive cyclogenesis placed at
the Gulf of Vizcaya, reached its maximum intensity with observed surface
pressures below 970 hPa on its center. During its path through the south of
France there were strong westerly and north-westerly winds over Iberian
Peninsula (above 150 km/h). These extreme winds leaved 8 casualties in
Catalunya, the north-east region of Spain.
The aim of this work is validating the skill of the Spanish Meteorological
Agency (AEMET) Short Range Ensemble Prediction System (SREPS) in forecasting
this event. Two probabilistic forecasts of wind are compared, a
non-calibrated (or raw) and a calibrated one using the Bayesian Model
Averaging (BMA).
AEMET runs a daily experimental SREPS twice a day (00:00 and
12:00 UTC). This system consists on 25 members that are constructed by
integrating five different Limited Area Models (LAMs) at 0.25 degrees of
horizontal resolution. Each model uses five different initial and boundary
conditions from five Global Models (GMs). Thus it is obtained a probabilistic
forecast that takes into account initial, contour and model uncertainties.
BMA is a statistical tool for combining predictive Probability Distribution
Functions (PDFs) from different sources. BMA predictive PDF is a weighted
average of PDFs centered on the individual bias-corrected forecasts. Each
weight is a measure of the corresponding forecast skill. Here BMA is applied
to calibrate probabilistic forecasts of wind speed.
In this work two time forecast ranges (H+60 and H+36) of 10-m wind
speed over Catalonia are verified subjectively at 12:00 UTC of 24Jan09 valid
time. We focus on the location and intensity of 10-m wind speed maximum
values. Observations at 29 automatic ground stations of AEMET are used for
the verification.
On one hand results indicate that raw AEMET-SREPS is able to forecast 60 h
ahead mean winds higher than 36 and 54 km/h and that it correctly
locates them in three different areas. On the other hand, predicted
probability loses its skill after BMA calibration of the ensemble. This is
due to the fact that BMA bias correction underestimates the intensity of
wind. |
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