Generation of Quasi‐Biweekly Yanai Waves in the Equatorial Indian Ocean

Arzeno, Isabella B.; Giddings, Sarah N.; Pawlak, Geno; Pinkel, Robert

doi:10.1029/2020gl088915

Cited by 6 publications

(32 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Arzeno et al. (2020) reported westward propagating biweekly mixed Rossby‐gravity waves in satellite altimetry with a mean phase speed of 3.4 m s −1 , which is close to our c x estimates considering the uncertainties.…”

Section: Basin‐scale Structure Of the Biweekly Wavessupporting

confidence: 91%

“…Aided by satellite and reanalysis products, we also examine the biweekly mixed Rossby‐gravity wave's basin‐scale structure and how it corresponds with the flow fields inferred from the moored velocities. Our interpretation of the moored velocity and satellite‐derived data in terms of Rossby‐gravity wave theory extends the results of past studies that are exclusively based on either satellite products (e.g., Arzeno et al., 2020), sparser mooring data (e.g., Sengupta et al., 2004), or numerical experiments (Miyama et al., 2006).…”

Section: Introductionsupporting

confidence: 85%

See 1 more Smart Citation

Biweekly Mixed Rossby‐Gravity Waves in the Equatorial Indian Ocean

Pujiana

McPhaden

2021

JGR Oceans

View full text Add to dashboard Cite

The tropical Indian Ocean exhibits a host of wind-forced oceanic phenomena across a broad spectrum of timescales from days to years that are fundamental in regulating ocean-atmosphere interactions and climate on both regional and global scales. Most notable are the seasonally reversing ocean currents driven by Asian monsoon winds (e.g., Schott et al., 2009) and the unique surface eastward jet that appears twice a year along the equator in response to energetic westerlies during the transitions between the Northeast and Southwest monsoons (e.g., McPhaden, 1982;Wyrtki, 1973). Another unique feature of the circulation is the seasonal cross-equatorial meridional overturning circulation, with frictional flow at the surface toward the winter hemisphere in the open ocean and a return flow in the thermocline below (Miyama, McCreary, Jensen, et al., 2003;Wang & McPhaden, 2017). Embedded within this monsoon wind-driven circulation are intraseasonal variations associated with the atmospheric Madden-Julian oscillation (MJO) (e.g., Zhang, 2013) that excite large-scale oceanic responses in terms of equatorial waves and mixed layer dynamics (e.g., Nagura & McPhaden, 2008;Pujiana et al., 2018).Although not as well studied as the above phenomena, near surface variations in the biweekly period band are very prominent. Reppin et al. (1999), using near-surface current meter data at 80.

show abstract

Section: Basin‐scale Structure Of the Biweekly Wavessupporting

confidence: 91%

Section: Introductionsupporting

confidence: 85%

Biweekly Mixed Rossby‐Gravity Waves in the Equatorial Indian Ocean

Pujiana

McPhaden

2021

JGR Oceans

View full text Add to dashboard Cite

show abstract

“…Moreover, the ADCPE velocity spectrum (Figure 7) shows a significant peak at a period of about 15 days, suggesting an influence from wind‐forced Yanai waves over the SP region. In further support of this hypothesis seasonality in current variance is also observed at these periods, with larger amplitudes at the peak of the monsoons in February and August (Figure 8), consistent with the seasonal variability of the Yanai waves (Arzeno et al., 2020; Chatterjee et al., 2013). These waves impinge on the SP and, in turn, produce plateau‐trapped signals with maximum amplitudes during monsoon months when winds are stronger than during intermonsoon periods.…”

Section: Discussionsupporting

confidence: 80%

“…At frequencies lower than 7 days, a significant peak in the counterclockwise energy at a period of 15 days reflects the influence of intraseasonal variability. This period suggests the influence of equatorial mixed Rossby‐gravity (Yanai) waves on the SP (Arzeno et al., 2020; Chatterjee et al., 2013; Kindle & Thompson, 1989; Luyten & Roemmich, 1982; Sengupta et al., 2004; Schott et al., 2009).…”

Section: Observations Atop the Seychelles Plateaumentioning

confidence: 99%

Observations and Modeling of Ocean Circulation in the Seychelles Plateau Region

et al. 2021

Self Cite

View full text Add to dashboard Cite

The ocean circulation around and over the Seychelles Plateau (SP) is characterized using 35 months of temperature and velocity measurements along with a numerical model. The results here provide the first documented description of the ocean circulation atop the SP. The SP is an unusually broad (∼200 km), shallow (∼50 m) plateau, dropping off steeply to the abyss. It is situated in a dynamic location (3.5–5.5°S, 54‐57°E) in the south‐western tropical Indian Ocean where northwesterly winds are present during austral summer and become southeasterly in austral winter, following the reversal of the western Indian ocean monsoon winds. Measurements around the Inner Islands, on the SP, have been carried out since 2015. Velocity measurements show that most of the depth‐averaged current variance on the SP arises from near‐inertial oscillations and lower‐frequency variability. Lower‐frequency variability encompasses seasonal and intraseasonal variability, the latter of which includes the effects of mixed Rossby‐gravity waves and mesoscale eddies. A global 0.1° numerical ocean simulation is used in conjunction with these observations to describe the regional circulation around the SP. Atop the SP, circulation is dominated by ageostrophic processes consistent with Ekman dynamics, while around the SP, both geostrophic and ageostrophic processes are important and vary seasonally. Stratification responds to the sea surface height semiannual signal which is due to Ekman pumping‐driven upwelling (related to the Seychelles‐Chagos Thermocline Ridge) and the arrival of an annual downwelling Rossby wave.

show abstract

“…Although Yanai wave energy is strongest in the eastern region of the Indian Ocean (Chatterjee et al., 2013; Miyama et al., 2006), Arzeno et al. (2020) argue that vertical mode‐2 Yanai waves are generated westward of the Seychelles Plateau. As previously observed by Sengupta et al.…”

Section: Introductionmentioning

confidence: 99%

Generation of Low‐Latitude Seamount‐Trapped Waves: A Case Study of the Seychelles Plateau

et al. 2021

Self Cite

View full text Add to dashboard Cite

Baroclinic seamount‐trapped waves are thought to influence their surrounding ecosystem; however, trapped waves are not well‐studied in near‐equatorial settings, where stratification is strong and Burger numbers (S=N2H2f2LH2) are large. Motivated by observations, we use daily output (2005–2009) from the global Parallel Ocean Program Model (POP) to examine topographically trapped baroclinic waves around the Seychelles Plateau (S>400) in the tropical Indian Ocean. These trapped waves are associated with velocity and temperature oscillations at periods of 15–16 days, similar to the dominant period of some equatorial Yanai waves. Energy flux maps using POP output suggest that quasi‐biweekly equatorial Yanai waves excite trapped waves on the western and south‐western flanks of the Seychelles Plateau, near the surface. The anticyclonic energy flux associated with the trapped wave extends vertically throughout the water column and around most of the plateau circumference, diminishing on the eastern flank of the plateau. This work highlights the role that equatorial planetary waves and trapped waves play in facilitating energy redistribution, dissipation, and mixing in the tropical ocean.

show abstract

Generation of Quasi‐Biweekly Yanai Waves in the Equatorial Indian Ocean

Cited by 6 publications

References 42 publications

Biweekly Mixed Rossby‐Gravity Waves in the Equatorial Indian Ocean

Biweekly Mixed Rossby‐Gravity Waves in the Equatorial Indian Ocean

Observations and Modeling of Ocean Circulation in the Seychelles Plateau Region

Generation of Low‐Latitude Seamount‐Trapped Waves: A Case Study of the Seychelles Plateau

Contact Info

Product

Resources

About