A statistical analysis of mesoscale eddies in the Bay of Bengal from 22–year altimetry data

Cui, Wei; Yang, Jungang; Ma, Yi

doi:10.1007/s13131-016-0945-3

Cited by 44 publications

(37 citation statements)

References 29 publications

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“…4. The amplitude of the eddy was at least 3 cm (Chaigneau et al, 2011;Cui et al, 2016). The amplitude of an eddy was defined as the absolute value of the SLA difference between the eddy center and its edge.…”

Section: Eddy Identification and Some Improvementsmentioning

confidence: 99%

“…Therefore, even though the AVISO gridded SLA products represent the merging of data from different altimeters, it is difficult to claim that ocean signals under a variance of 2 cm could be captured precisely in the SLA fields, especially for the gaps in altimeter tracks that are interpolated from other observation points. This change avoided large, ameba-like eddy structures effectively because eddies with amplitude less than 3 cm tended to be broad and relatively flat (Cui et al, 2016;Dufau et al, 2016).…”

Section: Eddy Identification and Some Improvementsmentioning

confidence: 99%

“…By combining satellite altimetry and Argo profiling float data, Zhang et al (2014) found that eddy-induced zonal mass transport was comparable in magnitude to that of the large-scale wind-and thermohalinedriven circulation, which suggested mesoscale eddies have a strong impact on global climate change and air-sea interaction. Mesoscale eddies also have an important influence on the local circulation of marginal seas, such as the South China Sea (Zheng et al, 2017), the Bay of Bengal (Cui et al, 2016), or the Mediterranean Sea (Escudier et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…More and more research uses a purely geometric method based on sea level anomaly (SLA) that is more accurate and is becoming more of a mainstream method in recent years (Faghmous et al, 2015;Souza et al, 2011;Sun et al, 2017). The purely geometric method for eddy identification stems from Chelton et al (2011), and some developments and practical improvements have been made by many researchers (Cui et al, 2016;Mason et al, 2014;Schlax and Chelton, 2016). Chelton et al (2011) recognized that their original identification algorithm can yield eddies with more than one local extremum of SLA.…”

Section: Introductionmentioning

confidence: 99%

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Multicore structures and the splitting and merging of eddies in global oceans from satellite altimeter data

et al. 2019

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Abstract. This study investigated the statistics of eddy splitting and merging in the global oceans based on 23 years of altimetry data. Multicore structures were identified using an improved geometric closed-contour algorithm of sea surface height. Splitting and merging events were discerned from continuous time series maps of sea level anomalies. Multicore structures represent an intermediate stage in the process of eddy evolution, similar to the generation of multiple nuclei in a cell as a preparatory phase for cell division. Generally, splitting or merging events can substantially change (by a factor of 2 or more) the eddy scale, amplitude, and eddy kinetic energy. Specifically, merging (splitting) generally causes an increase (decrease) of eddy properties. Multicore eddies were found to tend to split into two eddies with different intensities. Similarly, eddy merging is not an interaction of two equal-intensity eddies, and it tends to manifest as a strong eddy merging with a weaker one. A hybrid tracking strategy based on the eddy overlap ratio, considering both multicore and single-core eddies, was used to confirm splitting and merging events globally. The census revealed that eddy splitting and merging do not always occur most frequently in eddy-rich regions; e.g., their frequencies of occurrence in the Antarctic Circumpolar Current and western boundary currents were found to be greater than in midlatitude regions (20–35∘) to the north and south. Eddy splitting and merging are caused primarily by an unstable configuration of multicore structures due to obvious current– or eddy–topography interaction, strong current variation, and eddy–mean flow interaction.

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Section: Eddy Identification and Some Improvementsmentioning

confidence: 99%

Section: Eddy Identification and Some Improvementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multicore structures and the splitting and merging of eddies in global oceans from satellite altimeter data

et al. 2019

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“…Benefitting from approximately three decades of high spatiotemporal coverage of satellite measurements, the horizontal evolution patterns (e.g., the genesis, polarity, propagation, lifetime and spatiotemporal variability) and kinematic properties of the BOB eddies have been thoroughly investigated through a statistical analysis of altimeter data (e.g., [14][15][16]). The abovementioned eddy-rich domain in the western boundary that was revealed by field observations has been fully confirmed [14,16]. In addition, another critical region for eddy generation is located at the eastern boundary over the BOB, according to altimeter measurements [14,[16][17].…”

Section: Introductionmentioning

confidence: 99%

Thermohaline Structures and Heat/Freshwater Transports of Mesoscale Eddies in the Bay of Bengal Observed by Argo and Satellite Data

2019

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Knowledge of mesoscale eddies in the Bay of Bengal (BOB) is key for further understanding the climate variability in this region and beyond, but little is known about the vertical structure of these eddies. In this study, the three−dimensional structure and transport characteristics of mesoscale eddies in the BOB were comprehensively investigated by the combined use of Argo profiles and satellite data. The composite analysis showed that eddy−induced ocean anomalies are mainly confined to the upper 300 m of the water. The spatial structure of eddy−induced thermohaline perturbations is characterized by a dominant dipole structure in the near surface layer, arising from horizontal advection of the background thermohaline gradient by eddy rotation, and a monopole structure in the subsurface layer, caused by eddy−induced vertical displacements of the isopycnal surfaces. In the eddy core, the maximum temperature anomalies induced by a cyclonic eddy (CE) and an anticyclonic eddy (AE) are about −1.2 °C and +1.2 °C, respectively. The anomalies are located at approximately 100 m. The corresponding salinity anomalies are located at approximately 50 m with a value of −0.1 psu (0.1 psu) for CE (AE). The eddy thermohaline structure has a seasonal character. A deeper temperature and salinity core occurs in both CE and AE in spring compared to that in other seasons, which is primarily caused by the relatively deep thermocline and halocline during that season. In addition, unique warming anomalies induced by CE are present in the mixed layer during winter due to the vertical advection of the BL (Barrier Layer) warmer water by eddies. The total meridional heat transport induced by the composite eddy is poleward (equatorward) south (north) to 10°N with a value of 0.01 PW (−0.013 PW), whereas the total meridional freshwater transport is equatorward with a value of 0.046 Sv over a one−year period. The volume of freshwater export out of the bay is approximately 35% of the annual net freshwater input from local precipitation and river discharge.

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Mesoscale eddies with anomalous sea surface temperature and its relation with atmospheric convection over the North Indian Ocean

Gulakaram

Anandh

Bhaskaran

2023

Intl Journal of Climatology

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Mesoscale eddies are the important phenomenon of world oceans that play a prominent role in influencing the near-surface atmosphere and transport of heat. Ocean and atmosphere responses due to the presence of oceanic mesoscale eddies are not well studied in the Northern Indian Ocean (NIO) region.The present study analysed the ocean and atmospheric response due to the presence of mesoscale eddies using a composite analysis. Generally, it is assumed that the anti-cyclonic eddies are associated with the positive anomalies of sea surface temperature (SST), and cyclonic eddies are accompanied by negative anomalies. However, for the two marginal seas in the NIO, that is, the Bay of Bengal (BoB) and Arabian Sea (AS), the composite picture of SST anomalies associated with mesoscale eddies showed an abnormal response of SST. This unusual behaviour of cold SST near anti-cyclonic eddies and warm SST near cyclonic eddies in BoB and AS is analysed with the mean composites of precipitation, outgoing longwave radiation (OLR), and turbulent fluxes. The mean composites over all anti-cyclonic eddies reveal the presence of enhanced precipitation and convection (low OLR), whereas over cyclonic eddies, suppressed convection and negative precipitation anomalies are evident. The composites of latent heat flux (LHF), precipitation and OLR near surface cold anticyclonic eddies indicate the loss of heat from the ocean to the atmosphere, intense precipitation along with cloudy conditions are responsible for the cooling of the ocean. Along with this, stronger winds are also evident during cloudy conditions could play a role in anomalous cooling of SST observed near anti-cyclonic through intense surface mixing. Similarly, vice versa is observed near the surface warm cyclonic eddies. The overlying atmosphere and abnormal response of SST near oceanic eddies are essential for understanding the significant role of oceanic mesoscale eddies in influencing the large-scale circulation of the atmosphere and climate.

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A statistical analysis of mesoscale eddies in the Bay of Bengal from 22–year altimetry data

Cited by 44 publications

References 29 publications

Multicore structures and the splitting and merging of eddies in global oceans from satellite altimeter data

Multicore structures and the splitting and merging of eddies in global oceans from satellite altimeter data

Thermohaline Structures and Heat/Freshwater Transports of Mesoscale Eddies in the Bay of Bengal Observed by Argo and Satellite Data

Mesoscale eddies with anomalous sea surface temperature and its relation with atmospheric convection over the North Indian Ocean

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