Kinetic Energy Budget Analysis During Interaction of Tropical Storm Candy (1968) with an Extratropical Frontal System

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  • 1 Department of Geosciences, Purdue University, West Lafayette, Ind. 47907
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Abstract

A kinetic energy budget over the central United States is constructed using the quasi-Lagrangian scheme of Vincent and Chang (1973), during the 12 h time period 0000–1200 GMT 25 June 1968 when Tropical Storm Candy interacted with a developing extratropical frontal system. Although it is difficult to specifically establish some of the interacting physical mechanisms without consideration of an available potential energy budget, the kinetic energy results, in addition to computations of the release of available potential energy, suggest that there is an interaction taking place between the two cyclone systems.

The major results of the study were as follows: 1) there is a large export of kinetic energy, primarily in the upper troposphere, from the extratropical baroclinic zone toward the tropical system; 2) the tropical system remains warm core during and after interaction with the cold-air-advecting baroclinic zone; 3) the release of available potential energy by the tropical system increases during the 12 h period while that of the extratropical system decreases; 4) the generation of kinetic energy within the tropical system is small, while that within the extratropical system is a dominant energy source, particularly in the upper troposphere where it counterbalances kinetic energy outflow; and 5) subgrid-scale processes (e.g., convective latent heat release and eddy kinetic energy exchange associated with jet stream activity) appear to be important energy sources.

In addition to the main body of results a random error analyses is performed on the grid-point wind and geopotential height data. The kinetic energy results remain essentially unchanged.

Abstract

A kinetic energy budget over the central United States is constructed using the quasi-Lagrangian scheme of Vincent and Chang (1973), during the 12 h time period 0000–1200 GMT 25 June 1968 when Tropical Storm Candy interacted with a developing extratropical frontal system. Although it is difficult to specifically establish some of the interacting physical mechanisms without consideration of an available potential energy budget, the kinetic energy results, in addition to computations of the release of available potential energy, suggest that there is an interaction taking place between the two cyclone systems.

The major results of the study were as follows: 1) there is a large export of kinetic energy, primarily in the upper troposphere, from the extratropical baroclinic zone toward the tropical system; 2) the tropical system remains warm core during and after interaction with the cold-air-advecting baroclinic zone; 3) the release of available potential energy by the tropical system increases during the 12 h period while that of the extratropical system decreases; 4) the generation of kinetic energy within the tropical system is small, while that within the extratropical system is a dominant energy source, particularly in the upper troposphere where it counterbalances kinetic energy outflow; and 5) subgrid-scale processes (e.g., convective latent heat release and eddy kinetic energy exchange associated with jet stream activity) appear to be important energy sources.

In addition to the main body of results a random error analyses is performed on the grid-point wind and geopotential height data. The kinetic energy results remain essentially unchanged.

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