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| Titel |
Objective quantification of perturbations produced with a piecewise PV inversion technique |
| VerfasserIn |
L. Fita, R. Romero, C. Ramis |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 25, no. 11 ; Nr. 25, no. 11 (2007-11-29), S.2335-2349 |
| Datensatznummer |
250015944
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| Publikation (Nr.) |
 copernicus.org/angeo-25-2335-2007.pdf |
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| Zusammenfassung |
| PV inversion techniques have been widely used in numerical studies of severe
weather cases. These techniques can be applied as a way to study the sensitivity of the
responsible meteorological system to changes in the initial conditions of the
simulations. Dynamical effects of a collection of atmospheric features involved in the
evolution of the system can be isolated. However, aspects, such as the definition of the
atmospheric features or the amount of change in the initial conditions, are largely
case-dependent and/or subjectively defined. An objective way to calculate the modification
of the initial fields is proposed to alleviate this problem. The perturbations are
quantified as the mean absolute variations of the total energy between the original and
modified fields, and an unique energy variation value is fixed for all the perturbations
derived from different PV anomalies. Thus, PV features of different dimensions and
characteristics introduce the same net modification of the initial conditions from an
energetic point of view. The devised quantification method is applied to study the
high impact weather case of 9–11 November 2001 in the Western Mediterranean
basin, when a deep and strong cyclone was formed. On the Balearic Islands 4 people died,
and sustained winds of 30 ms−1 and precipitation higher than 200 mm/24 h were
recorded. Moreover, 700 people died in Algiers during the first phase of the event. The
sensitivities to perturbations in the initial conditions of a deep upper
level trough, the anticyclonic system related to the North Atlantic high and the surface
thermal anomaly related to the baroclinicity of the environment are determined. Results
reveal a high influence of the upper level trough and the surface thermal anomaly and a
minor role of the North Atlantic high during the genesis of the cyclone. |
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