The Shape, Propagation and Mean-Flow Interaction of Large-Scale Weather Systems

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Abstract
For a zonal average operator the Eliassen-Palm flux provides a diagnostic of both eddy behavior and the feedback of the eddies onto the mean flow. This paper addresses the diagnosis problem for other averaging operators and, in particular, for time averaging which has proved in recent years such a powerful means of viewing the three-dimensional tropospheric flow. The horizontal velocity correlation tensor gives a measure of the characteristic horizontal eddy shape at a point. It also implies the direction of the group velocity relative to the mean flow in cases where such a concept is valid. However the major emphasis here is on the mean-flow feedback of eddies. In this respect, the eddy vorticity flux is determined by derivatives of the components of the anisotropic part of the tensor. Making a reasonable approximation allows the eddy vorticity flux convergence to be written in terms of E = (v′2 − u′2¯, u′v′¯). A simple interpretation of the mean flow feedback of eddies is then possible. A sligh... Abstract For a zonal average operator the Eliassen-Palm flux provides a diagnostic of both eddy behavior and the feedback of the eddies onto the mean flow. This paper addresses the diagnosis problem for other averaging operators and, in particular, for time averaging which has proved in recent years such a powerful means of viewing the three-dimensional tropospheric flow. The horizontal velocity correlation tensor gives a measure of the characteristic horizontal eddy shape at a point. It also implies the direction of the group velocity relative to the mean flow in cases where such a concept is valid. However the major emphasis here is on the mean-flow feedback of eddies. In this respect, the eddy vorticity flux is determined by derivatives of the components of the anisotropic part of the tensor. Making a reasonable approximation allows the eddy vorticity flux convergence to be written in terms of E = (v′2 − u′2¯, u′v′¯). A simple interpretation of the mean flow feedback of eddies is then possible. A sligh...

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