Satellite observations of the Pacific tropical instability wave characteristics and their interannual variability

Pezzi, Luciano Ponzi; Caltabiano, A.; Challenor, Peter

doi:10.1080/01431160500380588

Cited by 11 publications

(7 citation statements)

References 47 publications

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“…This study applied a twofold approach: a bidirectional (period and wavelength) band pass filter was used to extract the TIW signal, and this field 150 was considered as the perturbation, and a transient (time-dependent) basic state was defined, both for energetics. It will be shown that this methodology maintains TIW signal in a manner similar to that reported by Pezzi and Richards (Pezzi and Richards, 2003), Caltabiano et al (Caltabiano et al, 2005) and Pezzi et al (Pezzi et al, 2006). Consistent advancements regarding TIW physics and dynamics will be achieved with the employment of this methodology.…”

Section: Introductionsupporting

confidence: 75%

Revisiting Tropical Instability Wave Variability in the Atlantic Ocean using SODA reanalysis

Decco

Torres

Pezzi

et al. 2016

Preprint

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ABSTRACT. The spatial and temporal variability of energy exchange in Tropical Instability Waves (TIWs) in the Atlantic 15Ocean were investigated. A spectral analysis was used to filter the 5-day mean results from Simple Ocean Data Assimilation reanalysis spanning from 1958 to 2008. TIWs were filtered over periods of 15 to 60 days and between wavelengths of 4 and 20 longitude degrees. The main approach of this study was the use of bidirectionally filtered TIW time series as the perturbation fields, and the difference in these time series from the SODA total results was considered to be the basic state for energetics analysis. The main result was that the annual cycle (period of ~360 days) was the main source of variability of 20 the waves, and the semi-annual cycle (period of ~180 days) was a secondary variation, which indicated that TIWs occurred throughout the year but with intensity that varies seasonally. Barotropic instability acts as the mechanism that feeds and extracts energy to/from TIWs as alternate zonal bands at equatorial Atlantic. Baroclinic instability is the main mechanism that extracts energy from TIWs to the equatorial circulation north of Equator. All TIW patterns of variability were observed at west of ~10ºW. The present study reveals new evidences regarding TIW variability and suggests that future investigations 25 should include a detailed description of TIW dynamics as part of Atlantic Ocean equatorial circulation. IntroductionA Tropical Instability Wave (TIW) is defined as a cusp-shaped oscillation of the equatorial thermal front that propagates westward. These waves are associated with the seasonal variability of the 30 equatorial current system, and they are observed when the cold tongue ( Figure 1) is well established (Chelton et al., 2000; Jochum et al., 2004a, Legeckis andReverdin, 1987;Philander et al., 1986;Steger and Carton, 1991;Weisberg and Horigan, 1981). These westward waves have wavelengths ranging from 600 km to 2600 km and periods varying between 15 and 37 days in the Atlantic Ocean (Caltabiano et al., 2005;Chelton et al., 2000;Düing et al., 1975;Jochum et al., 2004b; Legeckis and Reverdin, 35 1987;Pezzi and Richards, 2003;Weisberg, 1984), and Athie and Marin (Athie and Marin, 2008) describes a wider range (periods of 15-50 days). The formation process is the naturally generated instability of the equatorial zonal current system with alternating bands of eastward and westward flows 1 Ocean Sci. Discuss., doi:10.5194/os-2016Discuss., doi:10.5194/os- -84, 2016 Manuscript under review for journal Ocean Sci. Published: 15 November 2016 c Author(s) 2016. CC-BY 3.0 License. (Philander, 1976). In the Atlantic, the zonal flows at the top ocean layers are modulated by the coupled air-sea dynamics and have a strong seasonal cycle, as presented by Stramma and Schott (Stramma and 40 Schott, 1999). The authors described the westward South Equatorial Current (SEC) as divided by three bands composed of northern, central and southern regions (the schematic surface circulation and its ...

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Section: Introductionsupporting

confidence: 75%

Revisiting Tropical Instability Wave Variability in the Atlantic Ocean using SODA reanalysis

Decco

Torres

Pezzi

et al. 2016

Preprint

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“…The Tropical Instability Waves (TIWs; Qiao and Weisberg, 1998;Pezzi et al 2006) are also likely to be a crucial factor in this region, although they are not fully resolved by the low-resolution model. Figure 8 depicts the horizontal TS fields at 50 m depth in the eastern equatorial Pacific on 13-17 October 2010, the peak of the 2010/ 2011 La Niña event.…”

Section: Discussion Of Factors In Increasing the Impactsmentioning

confidence: 99%

Evaluating the impacts of the tropical Pacific observing system on the ocean analysis fields in the global ocean data assimilation system for operational seasonal forecasts in JMA

Fujii

Ogawa²,

Brassington

et al. 2015

Journal of Operational Oceanography

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“…The RMS of AR and ARMA model residuals very clearly show the presence of the Tropical Instability Waves (TIWs), known also as Legeckis waves, in the equatorial Pacific in the form of equidistant spots separated by ∼1100 km (Legeckis, 1977;Philander et al, 1986;Lawrence and Angell, 2000;Liu et al, 2000;Kosek, 2001;Pezzi et al, 2006) (Figs. 2 and 3).…”

Section: Resultsmentioning

confidence: 99%

An Application of Low-Order Arma and Garch Models for Sea Level Fluctuations

Niedzielski¹,

Kosek²

2010

Artificial Satellites

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ABSTRACT. The paper presents the analysis of geographically-dependent irregular sea level fluctuations, often referred to as residual terms around deterministic signals, carried out by means of stochastic low-order autoregressive moving average (ARMA) and generalised autoregressive conditional heteroscedastic (GARCH) models. The gridded sea level anomaly (SLA) time series from TOPEX/Poseidon (T/P) and Jason-1 (J-1) satellite altimetry, commencing on 10th January 1993 and finishing on 14th July 2003, has been examined. The aforementioned models, limited to low-orders being combinations of 0,1 and 2, have been fitted to the SLA data. The root mean square and the Shapiro-Wilk test for the normal distribution have been used to calculate statistics of the residuals from these models. It has been found that autoregressive (AR) models as well as ARMA ones serve well the purpose of adequate modelling irregular sea level fluctuations, with a successful fit in some patchy bits of the equatorial Pacific. In contrast, GARCH models have been shown to be rather inaccurate, specifically in the vicinity of the tropical Pacific, in the North Pacific and in the equatorial Indian Ocean. The pattern of the Tropical Instability Waves (TIWs) has been noticed in the statistics of AR and ARMA model residuals indicating that the dynamics of these waves cannot be captured by the aforementioned linear stochastic processes.

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Satellite observations of the Pacific tropical instability wave characteristics and their interannual variability

Cited by 11 publications

References 47 publications

Revisiting Tropical Instability Wave Variability in the Atlantic Ocean using SODA reanalysis

Revisiting Tropical Instability Wave Variability in the Atlantic Ocean using SODA reanalysis

Evaluating the impacts of the tropical Pacific observing system on the ocean analysis fields in the global ocean data assimilation system for operational seasonal forecasts in JMA

An Application of Low-Order Arma and Garch Models for Sea Level Fluctuations

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