On The Release of Eddy Available Potential Energy in an Extratropical Cyclone System

Stephen E. Kenney Department of Geosciences, Purdue University, West Lafayette, IN 47907

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Phillip J. Smith Department of Geosciences, Purdue University, West Lafayette, IN 47907

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Abstract

A diagnostic analysis of energy conversion processes is undertaken to determine 1) the impact of latent heating and 2) the importance of scale in the release of available potential energy (APE). Data from moist and dry forecasts of an intense extratropical cyclone by the Drexel Limited Area Mesoscale Prediction System model are used to study the role of moist processes. Scale dependence is investigated by partitioning the quantity into an area average and eddy component and then separating the eddy component into long-wave and short-wave regimes.

The results show that the APE release is substantially larger in the moist case than in the dry case and that this difference is most pronounced in the major precipitation regions and above 500 mb. Also, the long-wave regime dominates over the short-wave regime, with the long-wave component comprising 96% of the eddy APE release.

Abstract

A diagnostic analysis of energy conversion processes is undertaken to determine 1) the impact of latent heating and 2) the importance of scale in the release of available potential energy (APE). Data from moist and dry forecasts of an intense extratropical cyclone by the Drexel Limited Area Mesoscale Prediction System model are used to study the role of moist processes. Scale dependence is investigated by partitioning the quantity into an area average and eddy component and then separating the eddy component into long-wave and short-wave regimes.

The results show that the APE release is substantially larger in the moist case than in the dry case and that this difference is most pronounced in the major precipitation regions and above 500 mb. Also, the long-wave regime dominates over the short-wave regime, with the long-wave component comprising 96% of the eddy APE release.

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