Quasi-Lagrangian Kinetic Energy Budgets of Composite Cyclone-Anticyclone Couplets

Tai-Jen George Chen Department of Atmospheric Science,State University of New York at Albany, Albany, N.Y. 12222

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Lance F. Bosart Department of Atmospheric Science,State University of New York at Albany, Albany, N.Y. 12222

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Abstract

A composite quasi-Lagrangian kinetic energy budget is constructed from four synoptically similar cases of polar air penetration into the Caribbean from off the North American continent. Computations were carried out for both the upstream anticyclone and downstream cyclone accompanying the polar outbreak.

Use of the residual technique suggests an average upscale energy exchange of 45.0 W m−2 over the anticyclone volume with a corresponding downscale energy transfer of 59.0 W m−2 over the cyclone volume for the 24 h period centered on the time of furthest southward cold air thrust as defined by the 1000–500 mb thickness patterns. The results also indicate that the vertical flux of kinetic energy ranges from 50 to 100% of the horizontal flux of kinetic energy and is of opposite sign below 400 mb in the cyclone volume. Further-more, during incipient surface cyclogenesis the horizontal boundary flux of 17.7 m m−2 is a signification of the local kinetic energy generation of 24.5 W m−2 whereas in the following 12 h time period these numbers become 32.2 and 64.6 W m−2, respectively. The corresponding figures for the anticyclone region include a horizontal export of kinetic energy of 37.2 and 55.0 W m−2 and local kinetic energy destruction of 9.5 and 6.0 W m−2 respectively, for the same 12 h time periods.

Abstract

A composite quasi-Lagrangian kinetic energy budget is constructed from four synoptically similar cases of polar air penetration into the Caribbean from off the North American continent. Computations were carried out for both the upstream anticyclone and downstream cyclone accompanying the polar outbreak.

Use of the residual technique suggests an average upscale energy exchange of 45.0 W m−2 over the anticyclone volume with a corresponding downscale energy transfer of 59.0 W m−2 over the cyclone volume for the 24 h period centered on the time of furthest southward cold air thrust as defined by the 1000–500 mb thickness patterns. The results also indicate that the vertical flux of kinetic energy ranges from 50 to 100% of the horizontal flux of kinetic energy and is of opposite sign below 400 mb in the cyclone volume. Further-more, during incipient surface cyclogenesis the horizontal boundary flux of 17.7 m m−2 is a signification of the local kinetic energy generation of 24.5 W m−2 whereas in the following 12 h time period these numbers become 32.2 and 64.6 W m−2, respectively. The corresponding figures for the anticyclone region include a horizontal export of kinetic energy of 37.2 and 55.0 W m−2 and local kinetic energy destruction of 9.5 and 6.0 W m−2 respectively, for the same 12 h time periods.

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