Seasonal variability of the Bay of Bengal circulation inferred from TOPEX/Poseidon altimetry

Eigenheer, Andreas; Quadfasel, Detlef

doi:10.1029/1999jc900291

Cited by 69 publications

(32 citation statements)

References 21 publications

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“…3). The surface current reverses its direction twice a year, in agreement with previous studies (Yu et al, 1991;McCreary et al, 1996;Shetye et al, 1996; Vinay- achandran and Yamagata, 1997; Vinayachandran et al, 1999;Eigenheer and Quadfasel, 2000;Durand et al, 2009;de Vos et al, 2014;Wijesekera et al, 2015;Lee et al, 2016). The mean meridional surface current is northward during boreal spring (Figs.…”

Section: Surface Circulationsupporting

confidence: 80%

“…The subsurface circulation in this region is also potentially important, as high-salinity water from the AS can be subducted beneath the fresher surface water originating from river runoff and precipitation in the northern BoB (Rao and Sivakumar, 2003;Sengupta et al, 2006;Vinayachandran et al, 2013;Gordon et al, 2016;Jensen et al, 2016); this is evident in observations and model studies both during the northeast (Wijesekera et al, 2015) and southwest monsoons (June-August) (Wijesekera et al, 2016b). Little is known about the subsurface structure of the boundary current along the east coast of Sri Lanka.…”

Section: Introductionmentioning

confidence: 99%

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An undercurrent off the east coast of Sri Lanka

et al. 2017

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Abstract. The existence of a seasonally varying undercurrent along 8 • N off the east coast of Sri Lanka is inferred from shipboard hydrography, Argo floats, glider measurements, and two ocean general circulation model simulations. Together, they reveal an undercurrent below 100-200 m flowing in the opposite direction to the surface current, which is most pronounced during boreal spring and summer and switches direction between these two seasons. The volume transport of the undercurrent (200-1000 m layer) can be more than 10 Sv in either direction, exceeding the transport of 1-6 Sv carried by the surface current (0-200 m layer). The undercurrent transports relatively fresher water southward during spring, while it advects more saline water northward along the east coast of Sri Lanka during summer. Although the undercurrent is potentially a pathway of salt exchange between the Arabian Sea and the Bay of Bengal, the observations and the ocean general circulation models suggest that the salinity contrast between seasons and between the boundary current and interior is less than 0.09 in the subsurface layer, suggesting a small salt transport by the undercurrent of less than 4 % of the salinity deficit in the Bay of Bengal.

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Section: Surface Circulationsupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

An undercurrent off the east coast of Sri Lanka

et al. 2017

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“…Rossby waves propagating westward from the eastern boundary are featured throughout the time-longitude plot ( (Yang et al 1998;Eigenheer and Quadfasel 2000), which was attributed to both local wind forcing and the remote forcing from the equatorial region (Yu et al 1991;Potemra et al 1991;McCreary et al 1993). The seasonal variation of SSHA in 2007-08 is consistent with the climatological seasonal pattern in the region (e.g., Yang et al 1998).…”

Section: Indoos and Satellite Observationssupporting

confidence: 59%

“…The local wind-driven circulation in the ocean interior is enhanced (weakened or reversed) if the waves are in the same phase as (opposite to) local wind stress curl. The dominant role of remote equatorial waves in seasonal wind-driven circulation of the Bay of Bengal has been studied extensively using numerical models and satellite SSHA observations (McCreary et al 1993;Vinayachandran et al 1996;Yang et al 1998;Eigenheer and Quadfasel 2000;Yu 2003). We have examined the respective roles of local and remote forcing in generating the band of high SSHA in the central bay using a linear reduced gravity model forced by QuikS-CAT winds.…”

Section: Indoos and Satellite Observationsmentioning

confidence: 99%

Ocean Preconditioning of Cyclone Nargis in the Bay of Bengal: Interaction between Rossby Waves, Surface Fresh Waters, and Sea Surface Temperatures*

McPhaden

2011

Journal of Physical Oceanography

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An in-depth data analysis was conducted to understand the occurrence of a strong sea surface temperature (SST) front in the central Bay of Bengal before the formation of Cyclone Nargis in April 2008. Nargis changed its course after encountering the front and tracked along the front until making landfall. One unique feature of this SST front was its coupling with high sea surface height anomalies (SSHAs), which is unusual for a basin where SST is normally uncorrelated with SSHA. The high SSHAs were associated with downwelling Rossby waves, and the interaction between downwelling and surface fresh waters was a key mechanism to account for the observed SST-SSHA coupling.The near-surface salinity field in the bay is characterized by strong stratification and a pronounced horizontal gradient, with low salinity in the northeast. During the passage of downwelling Rossby waves, freshening of the surface layer was observed when surface velocities were southwestward. Horizontal convergence of freshwater associated with downwelling Rossby waves increased the buoyancy of the upper layer and caused the mixed layer to shoal to within a few meters of the surface. Surface heating trapped in the thin mixed layer caused the fresh layer to warm, whereas the increase in buoyancy from low-salinity waters enhanced the high SSHA associated with Rossby waves. Thus, high SST coincided with high SSHA.The dominant role of salinity in controlling high SSHA suggests that caution should be exercised when computing hurricane heat potential in the bay from SSHA. This situation is different from most tropical oceans, where temperature has the dominant effect on SSHA.

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“…The jets advect the Arabian Sea's salty water eastward along the equator and thereby change the upper ocean salt budgets in the eastern Indian Ocean (Masson et al, 2004). Several observational studies have been conducted to address the hydrographic distributions and the associated circulation in the ETIO for the two monsoon periods and the boreal fall transition period (Suryanarayana et al, 1993;Eigenheer and Quadfasel, et al, 2000;Rao et al, 2006). The seasonal and interannual variability in circulation and its mechanism of formation in the ETIO have been previously studied using numerical models (Hacker et al, 1998;Jensen, 2001).…”

Section: Introductionmentioning

confidence: 99%

Hydrography and Circulation in the Eastern Tropical Indian Ocean during April-May 2011

Qiu

et al. 2012

Atmospheric and Oceanic Science Letters

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The distribution of hydrography and circulation in the eastern tropical Indian Ocean (ETIO) during April-May 2011 were analyzed using cruise observations, satellite observations, and historic hydrographic data. It was observed that warm water (>28°C) occupies the upper 50-m layer in the ETIO. Low-salinity surface water was observed at the mouth of the Bay of Bengal (BOB), which further extends to the Arabian Sea and off Sumatra via the Sri Lanka coast and the eastern bay mouth. Arabian Sea high-salinity water (ASHSW) is carried eastward along the equator to around 90°E by the equatorial undercurrent (EUC). It also runs south of Sri Lanka (north to 3°N) and in the western bay mouth (west to 87°E) but is much shallower than its counterpart at the equator. It is suggested to be the residual of the ASHSW, which intrudes into the BOB during the preceding southwest monsoon. Our results also show that, in the south of Sri Lanka, just below this subsurface high-salinity water, very-low-salinity water (about 34.8) occurs at depths of 100-200 m. Further analysis suggests that this low-salinity water comes from the BOB.

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Seasonal variability of the Bay of Bengal circulation inferred from TOPEX/Poseidon altimetry

Cited by 69 publications

References 21 publications

An undercurrent off the east coast of Sri Lanka

An undercurrent off the east coast of Sri Lanka

Ocean Preconditioning of Cyclone Nargis in the Bay of Bengal: Interaction between Rossby Waves, Surface Fresh Waters, and Sea Surface Temperatures*

Hydrography and Circulation in the Eastern Tropical Indian Ocean during April-May 2011

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