Long Wave Resonance in Tropical Oceans and Implications on Climate: The Pacific Ocean

Pinault, Jean-Louis

doi:10.1007/s00024-015-1212-9

Cited by 15 publications

(32 citation statements)

References 17 publications

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“…The resonance requires the adjustment of the natural period of the baroclinic waves to the forcing period. This is for example what occurs in the tropical Pacific during the annual and quadrennial QSWs [18]. It is also what is observed where the western boundary currents leave the continents to re-enter the interior flow of the subtropical gyres, while Rossby waves are embedded in the wind-driven circulation.…”

Section: Introductionsupporting

confidence: 51%

“…The 1-year period QSW is interpreted as a first vertical mode, fourth meridional mode Rossby wave resonantly forced by surface stress [18]. Antinodes ( Figure 1) are noticeable north of the equator, between 2 • N and 15 • N. The maximum height of the northernmost antinode is reached in June-July, which occurs between November-December for the southernmost antinode.…”

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confidence: 99%

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Resonantly Forced Baroclinic Waves in the Oceans: Subharmonic Modes

Pinault¹

2018

JMSE

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The study of resonantly forced baroclinic waves in the tropical oceans at mid-latitudes is of paramount importance to advancing our knowledge in fields that investigate the El Niño-Southern Oscillation (ENSO), the decadal climate variability, or the resonant feature of glacial-interglacial cycles that are a result of orbital forcing. Indeed, these baroclinic waves, the natural period of which coincides with the forcing period, have a considerable impact on ocean circulation and in climate variability. Resonantly Forced Waves (RFWs) are characterized by antinodes at sea surface height anomalies and nodes where modulated geostrophic currents ensure the transfer of warm water from an antinode to another, reflecting a quasi-geostrophic motion. Several RFWs of different periods are coupled when they share the same node, which involves the geostrophic forces at the basin scale. These RFWs are subject to a subharmonic mode locking, which means that their average periods are a multiple of the natural period of the fundamental wave, that is, one year. This property of coupled oscillator systems is deduced from the Hamiltonian (the energy) of the Caldirola-Kanai (CK) oscillator. In this article, it is shown how the CK oscillator, which is usually used to develop a phenomenological single-particle approach, is transposable to RFWs. Subharmonic modes ensure the durability of the resonant dissipative system, with each oscillator transferring as much interaction energy to all the others that it receives periodically.

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Section: Introductionsupporting

confidence: 51%

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confidence: 99%

Resonantly Forced Baroclinic Waves in the Oceans: Subharmonic Modes

Pinault¹

2018

JMSE

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“…RRH anomalies in Indonesia and in equatorial America are out of phase relative to the temporal reference -SOI (Figure 2), while the SST anomaly in the Central Pacific is in phase with -SOI [49]. This is because atmospheric Rossby and Kelvin waves induce high pressure on both sides of the Pacific.…”

Section: Regions Subject To the Rrh Oscillation In The 5-10 Year Bandmentioning

confidence: 92%

“…The most significant rainfall oscillation occurs in Indonesia and in equatorial America where it is closely linked to the SST anomaly extending in the central equatorial Pacific [49]. The RRH anomaly may reach 20% when the SST anomaly in the central Pacific is 0.45 °C ( Figure 5).…”

Section: Regions Subject To the Rrh Oscillation In The 5-10 Year Bandmentioning

confidence: 99%

Regions Subject to Rainfall Oscillation in the 5–10 Year Band

Pinault¹

2018

Climate

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Abstract:The decadal oscillation of rainfall in Europe that has been observed since the end of the 20th century is a phenomenon well known to climatologists. Consequences are considerable because the succession of wet or dry years produces floods or, inversely, droughts. Moreover, much research has tried to answer the question about the possible link between the frequency and the intensity of extra-tropical cyclones, which are particularly devastating, and global warming. This work aims at providing an exhaustive description of the rainfall oscillation in the 5-10 year band during one century on a planetary scale. It is shown that the rainfall oscillation results from baroclinic instabilities over the oceans. For that, a joint analysis of the amplitude and the phase of sea surface temperature anomalies and rainfall anomalies is performed, which discloses the mechanisms leading to the alternation of high and low atmospheric pressure systems. For a prospective purpose, some milestones are suggested on a possible link with very long-period Rossby waves in the oceans.

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“…Significant TIW signals appeared in boreal autumn and winter and became especially strong in La Niña years (Contreras, 2002;Moum et al, 2009;Pezzi, Caltabiano, & Challenor, 2006;Wu & Bowman, 2007;Yu & Liu, 2003). The TIWs can influence the El Niño-Southern Oscillation (ENSO), which is the strongest interannual variation signal in the tropical atmosphere-ocean system (e.g., Wang, Deser, Yu, DiNezio, & Clement, 2017;Xie, 2009), along with westerly wind bursts (e.g., Chen et al, 2015;Gebbie, Eisenman, Wittenberg, & Tziperman, 2007) and the resonance of baroclinic waves (e.g., Pinault, 2016Pinault, , 2018. The TIWs can heat the cold tongue through horizontal advection (e.g., Graham, 2014;Jochum, Cronin, Kessler, & Shea, 2007;Wang & McPhaden, 1999) and thus have a negative feedback on ENSO (e.g., An, 2008).…”

Section: Introductionmentioning

confidence: 99%

An Empirical Tropical Instability Wave-induced Wind Stress Model in the Equatorial Pacific and its Incorporation into the Ocean Model

2018

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Satellite observations revealed that there is a close relationship between perturbations of sea surface temperature (SST) and wind stress (τ) induced by tropical instability waves (TIWs; SST TIW and τ TIW ). Using the empirical relationship observed between TIW-induced wind stress divergence (curl) and downwind (crosswind) SST gradients, this study establishes a TIW-induced wind stress field perturbation model τ TIW = F(SST). This empirical model solves τ TIW from the TIW-induced wind stress divergence and curl, which are estimated from the downwind and crosswind SST gradients. This empirical τ TIW = F(SST) model can be incorporated into the ocean model to take into account the effect of τ TIW . By comparing two experiments with and without the τ TIW effect, this study demonstrates that τ TIW has a substantial effect on the equatorial Pacific heat budget and induces the long-term mean SST to exhibit a 0.2°C difference, which is consistent with previous studies. RÉSUMÉ [Traduit par la rédaction] Les observations émanant de satellites révèlent qu'il existe une relation étroite entre les ondes d'instabilité tropicales (TIW), et les perturbations de la température de surface de la mer (SST) et de la tension du vent (τ) que ces ondes induisent, soit SST TIW et τ TIW . Nous élaborons ici un modèle, τ TIW = F(SST), de perturbation du champ de la tension du vent que génèrent les TIW, et ce, en appliquant la relation empirique observée entre la divergence (le rotationnel) de la tension du vent et le gradient des SST en aval (perpendiculaire au vent), que produisent les TIW. Ce modèle empirique résout τ TIW à partir de la divergence et du rotationnel de la tension du vent qu'induisent les TIW, et ceux-ci sont estimés à partir des gradients de SST perpendiculaire au vent et en aval. Ce modèle empirique, τ TIW = F(SST), peut s'insérer dans le modèle océanique pour prendre en compte l'effet de τ TIW . En comparant des simulations avec et sans l'effet τ TIW , nous démontrons que τ TIW influe considérablement sur le bilan thermique du Pacifique équatorial et génère à long terme une différence de 0,2°C de la moyenne de la SST, ce qui concorde avec des études antérieures.

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Long Wave Resonance in Tropical Oceans and Implications on Climate: The Pacific Ocean

Cited by 15 publications

References 17 publications

Resonantly Forced Baroclinic Waves in the Oceans: Subharmonic Modes

Resonantly Forced Baroclinic Waves in the Oceans: Subharmonic Modes

Regions Subject to Rainfall Oscillation in the 5–10 Year Band

An Empirical Tropical Instability Wave-induced Wind Stress Model in the Equatorial Pacific and its Incorporation into the Ocean Model

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