Meridional Asymmetry and Energetics of Tropical Instability Waves

Yu, Zuojun; McCreary, Julian P.; Proehl, Jeffrey A.

doi:10.1175/1520-0485(1995)025<2997:maaeot>2.0.co;2

Cited by 76 publications

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“…This spectral peak is associated with TIWs, but a complete description cannot come from sea level fluctuations alone. The wide range of wavelengths and periods previously reported for TIWs (e.g., Table 1 of Qiao and Weisberg 1995, and references therein) and the multiple unstable modes found in linear stability analyses of the equatorial current system (e.g., McCreary and Yu 1992;Yu et al 1995;Lyman et al 2005) suggest that there are different instabilities occurring at different wavelengths and periods. It is becoming increasingly clear that there are strong disturbances that resemble mixed Rossbygravity waves, with higher frequencies (periods around 17 days), a strong meridional velocity signal on the equator, and a relatively weak sea level signal, as well as disturbances resembling equatorially trapped Rossby waves, with periods around 33 days and large sea level signals and subsurface vertical displacements near 58N (e.g., Miller et al 1985;Halpern et al 1988;McPhaden 1996;Lyman et al 2007).…”

Section: Introductionmentioning

confidence: 90%

Barotropic Rossby Waves Radiating from Tropical Instability Waves in the Pacific Ocean

Farrar

2011

Journal of Physical Oceanography

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Tropical instability waves are triggered by instabilities of the equatorial current systems, and their sea level signal, with peak amplitude near 58N, is one of the most prominent features of the dynamic topography of the tropics. Cross-spectral analysis of satellite altimetry observations shows that there is sea level variability in the Pacific Ocean as far north as Hawaii (i.e., 208N) that is coherent with the sea level variability near 58N associated with tropical instability waves. Within the uncertainty of the analysis, this off-equatorial variability obeys the dispersion relation for nondivergent, barotropic Rossby waves over a fairly broad range of periods (26-38 days) and zonal wavelengths (98-238 of longitude) that are associated with tropical instability waves. The dispersion relation and observed wave properties further suggest that the waves are carrying energy away from the instabilities toward the North Pacific subtropical gyre, which, together with the observed coherence of the sea level signal of the barotropic waves with that of the tropical instability waves, suggests that the barotropic Rossby waves are being radiated from the tropical instability waves. The poleward transport of kinetic energy and westward momentum by these barotropic Rossby waves may influence the circulation in the subtropics.

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Section: Introductionmentioning

confidence: 90%

Barotropic Rossby Waves Radiating from Tropical Instability Waves in the Pacific Ocean

Farrar

2011

Journal of Physical Oceanography

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“…Cox (1980) showed that baroclinic instability, though less important, is also a source of the EKE that is drawn from the mean potential energy. In addition, frontal instability (Yu et al 1995) and Kelvin-Helmholtz instability (Proehl 1996) were shown to be important EKE sources for the TIWs. A more comprehensive numerical study of the generation and the energetics of Pacific TIWs has shown that the northern temperature front is baroclincally unstable, while shear of the zonal currents causes barotropic instability at the equator (Masina et al 1999, hereafter MPB).…”

Section: Introductionmentioning

confidence: 98%

Feedback of Tropical Instability-Wave-Induced Atmospheric Variability onto the Ocean

et al. 2007

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The effects of atmospheric feedbacks on tropical instability waves (TIWs) in the equatorial Atlantic Ocean are examined using a regional high-resolution coupled climate model. The analysis from a 6-yr hindcast from 1999 to 2004 reveals a negative correlation between TIW-induced wind perturbations and TIW-induced ocean currents, which implies damping of the TIWs. On the other hand, the feedback effect from the modification of Ekman pumping velocity by TIWs is small compared to the contribution to TIW growth by baroclinic instability. Overall, the atmosphere reduces the growth of TIWs by adjusting its wind response to the evolving TIWs. The analysis also shows that including ocean current (mean ϩ TIWs) in the wind stress parameterization reduces the surface stress estimate by 15%-20% over the region of the South Equatorial Current. Moreover, TIW-induced perturbation ocean currents can significantly alter surface stress estimations from scatterometers, especially at TIW frequencies. Finally, the rectification effect from the atmospheric response to TIWs on latent heat flux is small compared to the mean latent heat flux.

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“…A validação desta combinação de dados encontra-se em Zhang et al (2006). Os dados diários utilizados neste trabalho são calculados a partir da média dos dados de resolução de 6 h. As componentes zonal e meridional da tensão de cisalhamento do vento são respectivamente calculadas da seguinte forma:…”

Section: Por Volta De 7-8unclassified

“…A identificação com base na teoria revelou que é possível diferenciar observa- (PHILANDER, 1978;YU et al, 1995). Na escala destas ondas, os mecanismos de interação oceano-atmosfera atuam de forma que a atmosfera responda aos fluxos de calor sensível e latente do oceano (CHELTON e XIE, 2010;SMALL et al, 2008).…”

Section: Considerações Finais E Sugestões De Trabalhos Futurosunclassified

“…[De Philander (1990); Cane e Sarachik (1976) FLAMENT et al, 1996). O desenvolvimento das ondas está associado à geração de instabilidades pelo intenso cisalhamento das correntes zonais que fluem em sentidos alternados (PHILANDER, 1978;COX, 1980) e aos fortes gradientes de temperatura da superfície do mar induzidos pela ressurgência equatorial (YU et al, 1995). Assim, as OITs podem ser observadas na região da língua fria, que limita as águas frias da ressurgência das águas quentes ao norte (LEGECKIS, 1977;DÜING et al, 1975 (HAYES et al, 1989;DESER et al, 1993;XIE et al, 1998;HASHIZUME et al, 2001;SMALL et al, 2003).…”

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Dinâmica e interação oceano-atmosfera de ondas de instabilidade tropical e ondas de Rossby curtas

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Meridional Asymmetry and Energetics of Tropical Instability Waves

Cited by 76 publications

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Barotropic Rossby Waves Radiating from Tropical Instability Waves in the Pacific Ocean

Barotropic Rossby Waves Radiating from Tropical Instability Waves in the Pacific Ocean

Feedback of Tropical Instability-Wave-Induced Atmospheric Variability onto the Ocean

Dinâmica e interação oceano-atmosfera de ondas de instabilidade tropical e ondas de Rossby curtas

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