The dynamics of a polar low assessed using potential vorticity inversion

The dynamics of a polar low are examined using a piecewise potential vorticity (PV) inversion method. In previous studies of this and other polar lows, structural evolution has been described in terms of regions of anomalous PV. In this study the relative importance of different PV anomalies and the...

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Bibliographic Details
Published in:Quarterly journal of the Royal Meteorological Society 2009-04, Vol.135 (641), p.880-893
Main Authors: Bracegirdle, Thomas J., Gray, Suzanne L.
Format: Article
Language:English
Subjects:
attribution
case‐study
cyclone
Earth, ocean, space
Exact sciences and technology
External geophysics
Meteorology
Physics of the high neutral atmosphere
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Summary:The dynamics of a polar low are examined using a piecewise potential vorticity (PV) inversion method. In previous studies of this and other polar lows, structural evolution has been described in terms of regions of anomalous PV. In this study the relative importance of different PV anomalies and the interactions between them have been quantified using PV diagnostics. The intensification of the polar low occurred in three stages (in contrast to previous studies of polar lows that have only identified two stages). The dynamical characteristics of stages one and two are consistent with the proposed type C cyclogenesis mechanism. A diabatically‐generated lower‐tropospheric PV anomaly dominated intensification after initial triggering by a positive upper‐level PV anomaly. A phase tilt between the upper and lower levels was maintained through retardation of the positive upper‐level anomaly by the effects of latent heat release. Stage three was a period of growth dominated by wind‐induced surface heat exchange (WISHE), which contributed at least 18% to the amplitude of the mature surface polar low. Copyright © 2009 Royal Meteorological Society
ISSN:0035-9009
1477-870X
DOI:10.1002/qj.411