Is there an effect of Bay of Bengal salinity on the northern Indian Ocean climatological rainfall?

Krishnamohan, K. S.; Vialard, Jérôme; Lengaigne, Matthieu; Masson, Sébastien; Samson, Guillaume; Pous, Stéphane; Suresh, N.; Durand, Fabien; Shenoi, S. S. C.; Madec, Gurvan

doi:10.1016/j.dsr2.2019.04.003

Cited by 20 publications

(10 citation statements)

References 55 publications

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“…This strong salinity stratification has important implications, because it inhibits vertical mixing (e.g. de Boyer et al 2007;Thadathil et al 2016; Krishnamohan et al 2019). Salinity stratification indeed reduces the cooling under tropical cyclones in the BoB right after the monsoon (Sengupta et al 2008;Neetu et al 2012), allowing a stronger surface evaporation that sustains the cyclone intensification (Neetu et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Redistribution of riverine and rainfall freshwater by the Bay of Bengal circulation

Chaitanya

Vialard²,

Lengaigne³

et al. 2021

Ocean Dynamics

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We use satellite-derived currents and a Lagrangian approach to investigate the redistribution of the precipitation minus evaporation (P-E) and river freshwater inputs into Bay of Bengal (BoB) by the oceanic circulation. We find a key role of Ekman transport in shaping the BoB freshwater distribution. Until September, the summer monsoon winds induce eastward Ekman transport, which maintains freshwater near its major rivers and rain sources in the northeastern BoB. The winter monsoon Ekman transport strongly contributes to the surface flow in many areas of the interior BoB. This ~ 0.15 m s−1 westward transport overcomes the weaker offshore transport by mesoscale motions and pushes a ~ 40/45% mixture of P-E and Ganges-Brahmaputra freshwater into the East Indian Coastal Current (EICC). In agreement with previous studies, we find that the EICC then transports Ganges-Brahmaputra freshwater southward, allowing the formation of a narrow freshwater tongue or "river in the sea" along the coast east of India in November. Ekman transport thus operates jointly with the EICC to allow the "river in the sea" formation. The EICC is nonetheless a "leaky pipe" as only ~ 22% of the Ganges-Brahmaputra, and ~ 9% of the P-E monsoonal freshwater inputs exit the BoB near Sri Lanka. The winter monsoon anticyclonic circulation in fact brings more rain freshwater from the equatorial Indian Ocean into the southeastern BoB than it exports freshwater through the EICC. As a result, the BoB circulation contributes to a net freshwater gain that amounts to 11% of the local rain and freshwater inputs.

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Section: Introductionmentioning

confidence: 99%

Redistribution of riverine and rainfall freshwater by the Bay of Bengal circulation

Chaitanya

Vialard²,

Lengaigne³

et al. 2021

Ocean Dynamics

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“…Li et al (2017a) use a combination of observations and modelling results to demonstrate that barrier layers in the Bay of Bengal influence the amplitude of intraseasonal oscillations in SST and precipitation. However, a recent coarse-resolution coupled modelling study suggests that freshwater has little influence on SST or rainfall, since the SST tendency caused by a reduction in mixing is offset by changes in surface heat fluxes (Krishnamohan et al, 2019).…”

Section: Vertical Mixingmentioning

confidence: 99%

Progress in understanding of Indian Ocean circulation, variability, air–sea exchange, and impacts on biogeochemistry

et al. 2021

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Abstract. Over the past decade, our understanding of the Indian Ocean has advanced through concerted efforts toward measuring the ocean circulation and air–sea exchanges, detecting changes in water masses, and linking physical processes to ecologically important variables. New circulation pathways and mechanisms have been discovered that control atmospheric and oceanic mean state and variability. This review brings together new understanding of the ocean–atmosphere system in the Indian Ocean since the last comprehensive review, describing the Indian Ocean circulation patterns, air–sea interactions, and climate variability. Coordinated international focus on the Indian Ocean has motivated the application of new technologies to deliver higher-resolution observations and models of Indian Ocean processes. As a result we are discovering the importance of small-scale processes in setting the large-scale gradients and circulation, interactions between physical and biogeochemical processes, interactions between boundary currents and the interior, and interactions between the surface and the deep ocean. A newly discovered regional climate mode in the southeast Indian Ocean, the Ningaloo Niño, has instigated more regional air–sea coupling and marine heatwave research in the global oceans. In the last decade, we have seen rapid warming of the Indian Ocean overlaid with extremes in the form of marine heatwaves. These events have motivated studies that have delivered new insight into the variability in ocean heat content and exchanges in the Indian Ocean and have highlighted the critical role of the Indian Ocean as a clearing house for anthropogenic heat. This synthesis paper reviews the advances in these areas in the last decade.

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“…Li et al (2017) intraseasonal oscillations in SST and precipitation. However, a recent coarse resolution coupled modelling study suggests that freshwater has little influence on SST or rainfall, since the SST tendency caused by a reduction in mixing is offset by changes in surface heat fluxes (Krishnamohan et al, 2019) Surface freshwater advection can create subsurface reservoirs of heat and salt that can be accessed when the winds are strong enough, such as during cyclones that regularly form in the Bay during October and November. In one dramatic example Qiu et al (2019) report up to 5 psu increases in SSS and only a smaller 0.5°C decrease in SST following the passage of Cyclone Phailin (2013).…”

Section: Vertical Mixingmentioning

confidence: 99%

Progress in understanding of Indian Ocean circulation, variability, air-sea exchange and impacts on biogeochemistry

Phillips

Tandon

Furue

et al. 2021

Preprint

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Abstract. Over the past decade, our understanding of the Indian Ocean has advanced through concerted efforts toward measuring the ocean circulation and its water properties, detecting changes in water masses, and linking physical processes to ecologically important variables. New circulation pathways and mechanisms have been discovered, which control atmospheric and oceanic mean state and variability. This review brings together new understanding of the ocean-atmosphere system in the Indian Ocean since the last comprehensive review, describing the Indian Ocean circulation patterns, air-sea interactions and climate variability. The second International Indian Ocean Expedition (IIOE-2) and related efforts have motivated the application of new technologies to deliver higher-resolution observations and models of Indian Ocean processes. As a result we are discovering the importance of small scale processes in setting the large-scale gradients and circulation, interactions between physical and biogeochemical processes, interactions between boundary currents and the interior, and between the surface and the deep ocean. In the last decade we have seen rapid warming of the Indian Ocean overlaid with extremes in the form of marine heatwaves. These events have motivated studies that have delivered new insight into the variability in ocean heat content and exchanges in the Indian Ocean, and climate variability on interannual to decadal timescales.This synthesis paper reviews the advances in these areas in the last decade.

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Is there an effect of Bay of Bengal salinity on the northern Indian Ocean climatological rainfall?

Cited by 20 publications

References 55 publications

Redistribution of riverine and rainfall freshwater by the Bay of Bengal circulation

Redistribution of riverine and rainfall freshwater by the Bay of Bengal circulation

Progress in understanding of Indian Ocean circulation, variability, air–sea exchange, and impacts on biogeochemistry

Progress in understanding of Indian Ocean circulation, variability, air-sea exchange and impacts on biogeochemistry

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