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| Titel |
Tracers of diabatic changes in potential temperature and potential vorticity: Integral interpretation in terms of net heating and circulation and applications to model consistency across resolutions |
| VerfasserIn |
Oscar Martinez-Alvarado, Suzanne Gray, John Methven |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250134645
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| Publikation (Nr.) |
 EGU/EGU2016-15389.pdf |
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| Zusammenfassung |
| Diabatic processes in the atmosphere can be characterised by the changes they produce on
potential temperature (θ) and potential vorticity (PV) following an air parcel. Diabatic tracers
of θ and PV track the changes undergone by those two variables due to the action of diabatic
processes in a Lagrangian frame by splitting θ and PV into components that are materially
conserved and components that are diabatically generated. Since diabatic tracers are subject
to advection by the three-dimensional wind field, they are useful tools for the investigation of
the interaction of diabatic processes with the atmospheric flow and the impact of diabatic
processes on the evolution of the atmosphere. In this contribution, we present a novel
integral interpretation of diabatic tracers over suitably defined control volumes,
which depend on the weather system under consideration. Using two contrasting
extratropical cyclones as examples, it is shown that θ tracers can be used to assess and
systematically compare the cross-isentropic mass transport around each cyclone, which
is related to the amount and distribution of heat produced during each cyclone’s
development. PV tracers are related to circulation and area-average isentropic vorticity
through the application of Stoke’s theorem. Using the impermeability theorem for PV,
which states there can be no PV flux across isentropic surfaces, it is also shown that
cross-isentropic motion within the control volumes does not directly influence circulation.
Instead, the influence of diabatic processes on the circulation crucially depends on the
balance between the fluxes along isentropic surfaces of the materially-conserved
and diabatically-generated PV components across the lateral boundaries of the
control volumes. Finally, the application of the integral interpretation of diabatic
tracers for the assessment of model consistency across different model resolutions is
discussed. |
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