Eddies and currents in the Bay of Bengal during summer monsoons

Pirro, Annunziata; Fernando, Harindra J. S.; Wijesekera, H. W.; Jensen, Tommy G.; Centurioni, Luca; Jinadasa, S.U.P.

doi:10.1016/j.dsr2.2019.104728

Cited by 20 publications

(17 citation statements)

References 39 publications

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“…High sea surface chlorophyll-a concentration (SSC) areas generally are identified in the upwelling and coastal areas feeding by nutrient-rich water from deeper layer and runoff, respectively (Figure 1a). The global SSC is found subject to multi-scale variability associated with ocean dynamical processes such as upwelling, mesoscale eddies, and sea ice melting [4][5][6][7]. Previous investigations show no significant trend in global annual median chlorophyll-a from 1998 to 2015 [8].…”

Section: Introductionmentioning

confidence: 93%

“…2021, 13, x FOR PEER REVIEW 2 of 20 deeper layer and runoff, respectively (Figure 1a). The global SSC is found subject to multiscale variability associated with ocean dynamical processes such as upwelling, mesoscale eddies, and sea ice melting [4][5][6][7]. Previous investigations show no significant trend in global annual median chlorophyll-a from 1998 to 2015 [8].…”

Section: Introductionmentioning

confidence: 93%

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Satellite-Observed Multi-Scale Variability of Sea Surface Chlorophyll-a Concentration along the South Coast of the Sumatra-Java Islands

Wei

et al. 2021

Remote Sensing

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The southern coast of Java is known as one of the most productive fishing grounds for tuna, feeding by nutrient-rich water along the coast caused by the subsurface water upwelling. This primary productivity can be evidenced by the high sea surface chlorophyll-a concentration (SSC). Based on satellite remote sensing products, we investigate the multi-scale variability in SSC along the Sumatra-Java coast. The results show that seasonal variability of SSCs is primarily due to monsoon-driven upwelling and rainfall in the Indian Ocean and Indonesian seas sides of the Sumatra and Java Islands, respectively. Local Ekman pumping plays a secondary role, while rainfall input to the ocean has little effect. Coastally trapped Kelvin waves and mesoscale eddies are responsible for the intraseasonal SSC anomalies in regions along the south coast of Java and off the Sunda and Lombok Straits, respectively. The interannual variability in SSC is caused by the anomalous upwelling related to the Indian Ocean Dipole. There was a weak increasing trend of ~0.1–0.2 mg/m3 per decade, above the global averaged trend, which may be related to enhanced local Ekman pumping. These analyses provide an overall description of SSC variations based on satellite observations; however, further investigations based on in situ observations are needed to achieve better quantification.

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Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 93%

Satellite-Observed Multi-Scale Variability of Sea Surface Chlorophyll-a Concentration along the South Coast of the Sumatra-Java Islands

Wei

et al. 2021

Remote Sensing

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“…The interaction between SMC and Rossby waves is complex, so the influence of SMC's location and strength on ISV of current and the distribution of eddy kinetic energy in BOB. Recent in situ observations show that the interaction between westward‐propagating Rossby waves and the SMC can affect the upper circulation variability at eastern Sri Lanka (Pirro, Fernando, et al., 2020; Wijesekera, Teague, et al., 2016) where the SMC's mainstream axis is located (Figure 1 in Wijesekera, Wang, et al., 2016). The process of eddy‐mean flow interactions for the northwestern Sumatra (around 90°E) has not been studied.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Intraseasonal Variability of the Upper Layers in the Southern Bay of Bengal During the Summer 2016

et al. 2021

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Intraseasonal variability (ISV) of the upper 500 m circulation in the southern Bay of Bengal (SBOB) is investigated by using mooring observations and analyzing model outputs. An enhanced ISV is found in the upper 500 m currents during summer 2016. In summer 2016, a boreal summer intraseasonal oscillation (BSISO) propagated northward in tropical Indian Ocean. The intraseasonal easterly anomaly associated with the BSISO forces the equatorial wave to propagate into SBOB, driving the ISV of the upper currents. However, the analysis shows that the enhancement of ISV may be more related to the oceanic instability. During summer 2016, the intensity of the southwest monsoon current (SMC) significantly increased with the position of the flow axis closer to the SBOB's eastern boundary. Energy analysis reveals that the SMC could strengthen the westward propagating Rossby wave through baroclinic and barotropic instability, which can lead to the enhanced ISV of the upper currents in SBOB.

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“…which is moving southward along the Sri Lanka coast, from warm, saltier water at the eastern end of the transect [16]. The latter represents the Arabian Sea water moving north/northeastward as the southwest monsoon current [18]. The shipboard ADCP measurements support this concept [8].…”

Section: Oceanography and Fisheries Open Access Journalmentioning

confidence: 72%

Turbulence and Mixing in Energetic Environment of the Coastal Waters of Sri Lanka

Jinadasa

2021

OFOAJ

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In order to obtain first insights on the ocean turbulence and mixing in the waters around Sri Lanka, the microstructure measurements in the South Monsoon Current to the south of Weligama (along 80.5°E and near the shelf break) and in the East Indian Coastal Current in the Bay of Bengal to the east of Trincomalee (along 8°N) was conducted by National Aquatic Resources Research and Development Agency (NARA) of Sri Lanka aboard the research vessel Samuddrika. It is shown that in strongly startified pycnocline, which is dynamically detached from the low-saline surface mixed layer, the probability distributions of the logarithm of the kinetic energy dissipation rate 10 log ε follow generalized extreme value (GEV) model. This could be associated with the occurrence of rare highly-energetic turbulent patches in the pycnocline due to intermittent breaking of internal-wave and sporadic shear-induced instabilities. The mixing Reynolds number (a nomalized eddy diffusivity) was found to be a function of the gradient Richardson number, and followed the parameterization proposed by [1].

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Eddies and currents in the Bay of Bengal during summer monsoons

Cited by 20 publications

References 39 publications

Satellite-Observed Multi-Scale Variability of Sea Surface Chlorophyll-a Concentration along the South Coast of the Sumatra-Java Islands

Satellite-Observed Multi-Scale Variability of Sea Surface Chlorophyll-a Concentration along the South Coast of the Sumatra-Java Islands

Enhanced Intraseasonal Variability of the Upper Layers in the Southern Bay of Bengal During the Summer 2016

Turbulence and Mixing in Energetic Environment of the Coastal Waters of Sri Lanka

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