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| Titel |
Potential Vorticity Attribution and Causality |
| VerfasserIn |
T. Spengler, J. Egger |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250060295
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| Zusammenfassung |
| The electrostatic analogy provides a well known paradigm for the concept of potential
vorticity (PV) attribution. Just as electric fields can be attributed to electric charges, so are
localized PV anomalies thought to induce far-fields of flow and temperature, at least after
geostrophic adjustment. Piecewise PV inversion (PPVI) exploits this concept. Idealized
examples of PPVI are discussed by selecting isolated anomalies which are inverted
to yield the far-field ’caused’ by the PV anomaly. The causality of attribution is
tested in this study by seeking an unbalanced initial state containing the same PV
anomaly but without a far-field from which the balanced state can be attained by
geostrophic adjustment. It is shown that the far-field of a balanced axisymmetric
PV-anomaly in shallow water, without mean PV-gradients, may evolve from a localized
anomaly without a far-field. For the more general example of the electrostatics
analogy, namely a three-dimensional spherical PV-anomaly, the initial state has to be
non-hydrostatic and needs to exhibit a mass deficit. As this mass deficit cannot be removed
during hydrostatic and geostrophic adjustment, it follows that PV attribution does not
imply a causal relationship between the far-field of a PV anomaly and the anomaly
itself. |
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