A Trial of Search for Minor Components of Lunar Tides and Short Period Free Oscillations of the Atmosphere in Surface Pressure Data

Matsuno, Taisuke

doi:10.2151/jmsj1965.58.4_281

Cited by 13 publications

(15 citation statements)

References 6 publications

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“…Because their eigenfrequencies are reasonably removed from zero and from one another, these gravest normal modes have proven individually distinguishable. (Although we have con-centrated exclusively on rotational modes, recent evidence has appeared for the gravest, wave number 1, eastward gravity mode: the Kelvin mode [Matsuno, 1980;Hamilton, 1984]. Its amplitude is smaller than those of the rotational modes, consistent with its shorter period, 32 hours.…”

Section: Discussionmentioning

confidence: 67%

Survey of planetary‐scale traveling waves: The state of theory and observations

Salby¹

1984

Reviews of Geophysics

252

186

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There exists a considerable body of evidence relating the gravest‐scale transient components of planetary wave activity (periods shorter than a couple of weeks) to the eigenmodes of an unbounded isothermal atmosphere in uniform rotation. The latter, termed “Lamb modes,” have horizontal structures of Hough functions, with a 10‐km equivalent depth, and the external vertical structure of a Lamb wave. They asymptote, for large total wave number, to normal modes of the nondivergent barotropic vorticity equation. Phase speeds of the gravest modes, however, are significantly retarded by divergence. A historical account of the development of large‐scale traveling waves is presented, culminating with the emergence of global observations and the identification of several modes in atmospheric data. Theoretical ingredients of the simple normal mode problem are reviewed. The relationship between these features and extratropical transients is developed via the notion of a “planetary wave spectrum.” Influences of realistic distributions of dissipation and refractive properties are discussed for a prototypical mode. Calculations for several of the gravest modes are then presented for typical climatological configurations. For all of these the simple eigenstructures are largely preserved at tropospheric levels. Recent observational evidence is collected from global satellite and conventional meteorological analyses and compared with theoretical concepts. An overview of realistic considerations, requisite for an understanding of “particular realizations” of these features, is developed. Response to localized, transient forcing is shown to consist not of any single mode, but rather of a spectrum of normal modes. For sufficiently large amplitudes, Lamb modes can give rise to vacillations in eddy flux fields via modulation of the stationary waves. These, in turn, may be accompanied by vacillations in the basic stream.

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Section: Discussionmentioning

confidence: 67%

Survey of planetary‐scale traveling waves: The state of theory and observations

Salby¹

1984

Reviews of Geophysics

252

186

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“…All these waves have easterly phase propagation and each has been identified with a particular normal mode Rossby wave (e. g., Salby, 1981a, b). Recently Matsuno (1980) has presented some limited evidence for the existence of another resonance.…”

Section: Introductionmentioning

confidence: 99%

“…It appears that this oscillation is reasonably coherent over the roughly 30* longitude separation of the stations.Following Matsuno (1980) this "33 hour wave" is tentatively identified with the gravest, zonal wavenumber one normal mode Kelvin wave. The present analysis makes possible the first determination of the surface pressure amplitude of this oscillation; this was found to be roughly one-fifth that of the more familiar "five day" Rossby normal mode in the tropics as estimated by Madden and Julian (1973) .…”

mentioning

confidence: 98%

Evidence for a Normal Mode Kelvin Wave in the Atmosphere

Hamilton

1984

Journal of the Meteorological Society of Japan

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Spectral analysis of long time series of three-hourly barometric observations at three Pacific Island stations was performed.In each case there was evidence for a peak in power near periods of about 33 hours. It appears that this oscillation is reasonably coherent over the roughly 30* longitude separation of the stations.Following Matsuno (1980) this "33 hour wave" is tentatively identified with the gravest, zonal wavenumber one normal mode Kelvin wave. The present analysis makes possible the first determination of the surface pressure amplitude of this oscillation; this was found to be roughly one-fifth that of the more familiar "five day" Rossby normal mode in the tropics as estimated by Madden and Julian (1973) .

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“…This oscillation displays a meridional structure that is equatorially trapped, like that anticipated for a Kelvin mode (although there are some large amplitudes at very high latitudes in the northern hemisphere as well). The external Kelvin normal mode in the atmosphere is predicted to have a period of about 33 h (Matsuno, 1980;Hamilton, 1984;Hamilton and Garcia, 1986), and so cannot be identified with the 4.8-day spectral peak seen in the model results. Both the rel.atively long period and short meridional trapping scale seen in Fig.…”

Section: Structure Offltered Feldsmentioning

confidence: 92%

Untitled

1987

Tellus A

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Atmospheric simulations produced by the Canadian Climate Centre general circulation model (GCM) were examined to detect Rossby normal modes such as the familiar "5-day" and "16-day" waves. Space-time spectral analysis of the simulated geopotential fields showed a concentration of power near the scales and frequencies predicted for the two gravest Rossby modes of both zonal wavenumbers one and two. By filtering the time series of simulated geopotential and wind fields in narrow bands around these spectral peaks, the vertical and meridional structures of these prominent oscillations were revealed. These structures were in good agreement with those theoretically predicted for the Rossby normal modes. The overall amplitudes of these modes appear to be realistic and even the day-today evolution of the modal amplitudes in the GCM is similar to that observed in the real atmosphere.A more complicated picture emerged when the same analysis was applied to the lower frequency "16-day" wave (i.e., the second gravest symmetric Rossby mode). The spectra produced from the GCM fields hiled to reproduce the peak in power in westward propagating zonal wavenumber one variance near 15-20 days that has been observed by Speth and Madden (1983). Examination of the geopotential field after it had been filtered to include only low frequency westward-propagating zonal wavenumber one variance did reveal at least one isolated episode when the meridional structure displayed some resemblance to the second gravest symmetric Rossby mode of theory. However, amplitudes are much stronger in the winter hemisphere than in the summer. A similar hemispheric asymmetry in the "16-day'' wave has been found in observations.The strength of the gravest symmetric zonal wavenumber one Rossby mode ("5-day" wave) was examined in a series of GCM simulations performed with climatological sea surface temperatures and in simulations that had anomalously warm sea surface temperatures imposed in the tropical Pacific. There is a clear tendency for the 5-day wave to be stronger in the simulations with warm Ocean temperatures, in agreement with observations of the interannual variability of this mode in real data.The excellent simulation of the gravest Rossby modes in the model suggests that the forcing and dissipation mechanisms for the modes in the GCM may also be realistic. An attempt was made to examine the forcing and dissipation of the modes in the model through a diagnostic study of the energetics of the simulated fields. The interaction with topography acts as a net sink for the modal energy. The dissipation arising from the parameterized mechanical friction in the GCM is much more important for these modes than that due to radiative heating and cooling.

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A Trial of Search for Minor Components of Lunar Tides and Short Period Free Oscillations of the Atmosphere in Surface Pressure Data

Cited by 13 publications

References 6 publications

Survey of planetary‐scale traveling waves: The state of theory and observations

Survey of planetary‐scale traveling waves: The state of theory and observations

Evidence for a Normal Mode Kelvin Wave in the Atmosphere

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