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Lagrangian and eulerian correlations and energy spectra of geostrophic velocities
Author(s) -
Kao S.K.,
Bullock W. S.
Publication year - 1964
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49709038406
Subject(s) - geostrophic wind , eulerian path , kinetic energy , zonal and meridional , autocorrelation , eddy diffusion , physics , spectral line , lagrangian , atmospheric sciences , mechanics , classical mechanics , turbulence , mathematics , mathematical physics , statistics , astronomy
An analysis is made of the dispersion of the end‐points of geostrophic trajectories initiated daily at 0000Z for the International Geophysical Year, 1958, at 500 mb over Seattle, Washington. Computations of the yearly mean of the Lagrangian autocorrelation coefficients and eddy diffusivities show that the Lagrangian integral time scale, ·, is equal to 5·0 × 10 4 sec. It is found that the zonal, x , and meridional, y , components of eddy diffusivity are respectively K x = 5·90 × 10 10 cm 2 sec −1 and K y = 2·30 × 10 10 cm 2 sec −1 . Spectral analysis of the kinetic energy of the Lagrangian geostrophic velocities shows that the kinetic energy densities of both the zonal and meridional components of the geostrophic winds generally increase from high to low frequency with a peak of the meridional component occurring at the frequency of 0·01 cycles hr −1 . Analyses are also made of the Eulerian autocorrelation coefficients and energy spectra of the geostrophic velocities. It is found that the Eulerian integral time‐scale, ϵ −1 , is equal to 9·4 × 10 4 sec, making the ratio of the Lagrangian and Eulerian time‐scales near 0·5.