Energy spectra within cut-off low regimes

The kinetic energy structure of two cut-off low situations is measured by the application of a numerical filtering technique. The filters are applied in both an east-west and a north- south direction to 500 mb geopotential height fields and the spectra for u and vcomponents of wind deduced. The results are summarised in four kinetic energy diagrams for each situation examined. Each diagram depicts the distribution of the kinetic energy spectral density of uorv, as a function of position and the easterly or northerly wavenumber component. The results are quantitative and show the importance of being able to resolve wavelengths of 1200 nautical miles and less in order to adequately resolve the cut-off low systems.