Frequency-wavenumber spectra of equatorial waves detected from satellite altimeter data

Wakata, Yoshinobu

doi:10.1007/s10872-007-0043-4

Cited by 29 publications

(17 citation statements)

References 18 publications

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“…It is demonstrated that wavenumber-frequency spectral analysis is useful for identifying signals of atmospheric equatorial waves including Yanai waves, and for isolating their structure. While the observed dispersion relationships of equatorial Kelvin and Rossby waves in the ocean were identified recently by wavenumber-frequency spectra of satellite-derived sea surface height (SSH) (Wakata 2007;Farrar 2008;Shinoda et al 2009), the resolution of the satellite altimeter data was insufficient to describe oceanic Yanai waves in frequency-wavenumber space until recently. This situation has begun to change because of multiple satellite launches in recent years.…”

Section: Introductionmentioning

confidence: 99%

Observed Dispersion Relation of Yanai Waves and 17-Day Tropical Instability Waves in the Pacific Ocean

Shinoda

2010

SOLA

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Using sea surface height (SSH) data derived from recent satellite observations, we present the observed dispersion relationship of mixed Rossby Gravity (Yanai) waves in the Pacific Ocean. A wavenumber-frequency spectral analysis of SSH fields shows prominent spectral peaks along the dispersion curves of first and second baroclinic mode oceanic Yanai waves. Also, salient features of tropical instability waves (TIWs) with a period of ~17 days can be effectively isolated based on a cross-correlation analysis of sea surface temperature (SST) and SSH time series that are filtered in wavenumber-frequency domain. These statistical representations of oceanic Yanai waves and TIWs are important for the evaluation of numerical model simulations of these waves and for improving our understanding of the physics of 17-day TIWs.

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Section: Introductionmentioning

confidence: 99%

Observed Dispersion Relation of Yanai Waves and 17-Day Tropical Instability Waves in the Pacific Ocean

Shinoda

2010

SOLA

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“…[The Tropical Atmosphere Ocean (TAO)-Triangle Trans-Ocean Buoy Network (TRITON) (McPhaden et al 1998) in the tropical Pacific would also allow such analyses, but those data will not be used here.] Studies using satellite altimetry observations to characterize the variability of equatorial sea level as a function of both zonal wavenumber and frequency are rare (e.g., Périgaud 1990;Zang et al 2002;Wakata 2007). The present study extends these previous efforts by applying methods used in the meteorological literature (Yanai and Murakami 1970;Zangvil and Yanai 1980;Wheeler and Kiladis 1999;Roundy and Frank 2004a) to altimetric data so as to allow further insight into the spectral characteristics of equatorial waves in the Pacific Ocean at periods exceeding a few weeks.…”

Section: Introductionmentioning

confidence: 82%

Observations of the Dispersion Characteristics and Meridional Sea Level Structure of Equatorial Waves in the Pacific Ocean

Farrar

2008

Journal of Physical Oceanography

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Spectral techniques applied to altimetry data are used to examine the dispersion relation and meridional sea level structure of wavelike variability with periods of about 20 to 200 days in the equatorial Pacific Ocean. Zonal wavenumber-frequency power spectra of sea surface height, when averaged over about 7°S-7°N, exhibit spectral peaks near the theoretical dispersion curves of first baroclinic-mode equatorial Kelvin and Rossby waves. There are distinct, statistically significant ridges of power near the first and second meridional-mode Rossby wave dispersion curves. Sea level variability near the theoretical Kelvin wave and first meridional-mode Rossby wave dispersion curves is dominantly (but not perfectly) symmetric about the equator, while variability near the theoretical second meridional-mode Rossby wave dispersion curve is dominantly antisymmetric. These results are qualitatively consistent with expectations from classical or shear-modified theories of equatorial waves.The meridional structures of these modes resemble the meridional modes of equatorial wave theory, but there are some robust features of the meridional profiles that were not anticipated. The meridional sea level structure in the intraseasonal Kelvin wave band closely resembles the theoretically expected Gaussian profile, but sea level variability coherent with that at the equator is detected as far away as 11.75°S, possibly as a result of the forced nature of these Kelvin waves. Both first and second meridional-mode Rossby waves have larger amplitude in the Northern Hemisphere. The meridional sea level structure of tropical instability waves closely resembles that predicted by Lyman et al. using a model linearized about a realistic equatorial zonal current system.

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“…However, despite chaotic behaviors in thermal equilibrium, the β-FPU chain can still exhibit certain regular structures, such as the effective dispersive characteristics [19,20]. The wave-number-frequency spectral (WFS) analysis [21][22][23] is applied to confirm the existence of the dispersion relation of these turbulent waves. The dispersion relation obtained from the WFS method, referred to as the renormalized * zdz@sjtu.edu.cn † cai@cims.nyu.edu dispersion relation, can deviate substantially from the linear dispersion.…”

Section: Introductionmentioning

confidence: 99%

Renormalized dispersion relations ofβ-Fermi-Pasta-Ulam chains in equilibrium and nonequilibrium states

Jiang

Zhou

et al. 2014

Phys. Rev. E

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We study the nonlinear dispersive characteristics in β-Fermi-Pasta-Ulam (FPU) chains in both thermal equilibrium and nonequilibrium steady state. By applying a multiple scale analysis to the FPU chain, we analyze the contribution of the trivial and nontrivial resonance to the renormalization of the dispersion relation. Our results show that the contribution of the nontrivial resonance remains significant to the renormalization, in particular, in strongly nonlinear regimes. We contrast our results with the dispersion relations obtained from the Zwanzig-Mori formalism and random phase approximation to further illustrate the role of resonances. Surprisingly, these theoretical dispersion relations can be generalized to describe dispersive characteristics well at the nonequilibrium steady state of the FPU chain with driving-damping in real space. Through numerical simulation, we confirm that the theoretical renormalized dispersion relations are valid for a wide range of nonlinearities in thermal equilibrium as well as in nonequilibrium steady state. We further show that the dispersive characteristics persist in nonequilibrium steady state driven-damped in Fourier space.

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Frequency-wavenumber spectra of equatorial waves detected from satellite altimeter data

Cited by 29 publications

References 18 publications

Observed Dispersion Relation of Yanai Waves and 17-Day Tropical Instability Waves in the Pacific Ocean

Observed Dispersion Relation of Yanai Waves and 17-Day Tropical Instability Waves in the Pacific Ocean

Observations of the Dispersion Characteristics and Meridional Sea Level Structure of Equatorial Waves in the Pacific Ocean

Renormalized dispersion relations ofβ-Fermi-Pasta-Ulam chains in equilibrium and nonequilibrium states

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