Recent changes in the summer monsoon circulation and their impact on dynamics and thermodynamics of the Arabian Sea

Kad, Pratik; Parekh, Anant; Karmakar, Ananya; Chowdary, Jasti S.; Gnanaseelan, C.

doi:10.1007/s00704-018-2493-6

Cited by 19 publications

(6 citation statements)

References 39 publications

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“…It is reported that during 1980–2014 the strength of the Findlater Jet enhanced 35 and future projections based on CMIP models suggest that it may further intensify in the warming climate 36 . Notably, at the same time, negative windstress curl over the interior Arabian Sea suggest a positive trend 37 , favouring upper ocean warming by deepening the thermocline. Since, strengthening of summer monsoon winds helps in enhancing the thermal gradient across the Arabian Sea and therefore, in combination with increasing upper ocean heat content, favouring an enhanced moisture transport to the Indian land masses.…”

Section: Discussionmentioning

confidence: 96%

Annihilation of the Somali upwelling system during summer monsoon

Chatterjee

Kumar

Prakash

et al. 2019

Sci Rep

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Somali upwelling system during northern summer is believed to be the largest upwelling region in the Indian Ocean and has motivated some of the early studies on the Indian Ocean. Here we present results from observations and ocean model to show that the upwelling along the Somali coast is limited to the early phase of the summer monsoon and later primarily limited to the eddy dominated flows in the northern and some extent in the southern part of the coast. Major part of the Somali coast (~60% of the entire coastal length) shows prominent downwelling features driven by offshore negative windstress curl and subsurface entrainment mixing. Further, we show that the surface cooling of coastal waters are dominantly driven by subsurface entrainment and surface heat fluxes. These findings not only augment the existing knowledge of the Somali upwelling system, but also have serious implications on the regional climate. Most importantly, our analysis underscores the use of alongshore winds only to project future (climate driven) changes in the upwelling intensity along this coast.

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Section: Discussionmentioning

confidence: 96%

Annihilation of the Somali upwelling system during summer monsoon

Chatterjee

Kumar

Prakash

et al. 2019

Sci Rep

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“…Contrary to expectation, there is a negative trend in the net heat flux despite the warming trend in the Indian Ocean SSTs (Rahul and Gnanaseelan 2013). This suggests that local ocean dynamics and ocean-atmosphere interaction also have a major role in the observed warming pattern in the Indian Ocean (Lau and Nath 2000;Du et al 2009;Rahul and Gnanaseelan 2016;Pratik et al 2019;Rao et al 2012). The period 2000-2013 witnessed strong warming in the southern Indian Ocean south of 10°S inducing a north-south SST gradient.…”

Section: Attribution Of Sst Trends To Anthropogenic Emissionsmentioning

confidence: 58%

Indian Ocean Warming

Roxy

Gnanaseelan

Parekh

et al. 2020

Assessment of Climate Change Over the Indian Region

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Sea surface temperature (SST) and upper ocean heat content (OHC, upper 700 m) in the tropical Indian Ocean underwent rapid warming during 1950–2015, with the SSTs showing an average warming of about 1 °C. The SST and OHC trends are very likely to continue in the future, under different emission scenarios. Climate models project a rise in tropical Indian Ocean SST by 1.2–1.6 °C and 1.6–2.7 °C in the near (2040–2069) and far (2070–2099) future across greenhouse gas (GHG) emissions scenarios RCP4.5 and RCP8.5, relative to the reference period of 1976–2005. Indian Ocean warming has very likely resulted in decreasing trend in oxygen (O2) concentrations in the tropical Indian Ocean, and declining trends in pH and marine phytoplankton over the western Indian Ocean. The observed trends in O2, pH and marine phytoplankton are projected to increase in the future with continued GHG emissions.

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“…7b,d). The surface warming trend over the Indian Ocean is mainly contributed by the trends in the curl of meridional wind stress vectors and associated transport than the heat fluxes (Swapna et al 2014;Rahul and Gnanaseelan 2016;Chowdary et al 2016;Pratik et al 2019). Nevertheless, the warming stabilizes the water column and for a given increase in wind stress, the change in mixing has to be ascertained.…”

Section: Resultsmentioning

confidence: 99%

Oceanic Mixing over the Northern Arabian Sea in a Warming Scenario: Tug of War between Wind and Buoyancy Forces

Praveen

Valsala

Ajayamohan

et al. 2020

Journal of Physical Oceanography

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A consensus of the twenty-first-century climate change in the ocean is surface warming, stratification due to extreme freshening and subsequent weakening of mixing, overturning circulation, and biological production. Counterintuitively, certain parts of the tropical ocean may develop a resistance to changes in mixing, where the climate change impacts of atmosphere and ocean are complementary to each other. Under the poleward shift of monsoon low-level jet (LLJ) in the twenty-first century, a part of the northern Arabian Sea has a tendency to maintain the mixed layer depth intact. The process is studied using a set of high-resolution regional ocean model downscaling experiments for the present and future climate. It is found that the wind intensification caused by the shift in LLJ tends to counteract the stratification gained by surface ocean warming and maintains the mixing process in a warming scenario. The mixing energetics shed light on the way in which this is achieved. Intensified winds promote shear production and surface ocean warming demotes buoyancy production of turbulent kinetic energy (TKE), with a net effect of an increase in TKE. However, TKE appears to be dissipating quickly because of the presence of a larger number of small-scale eddies. This causes the mixing length and mixed layer depth to remain intact. Therefore, the interpretations of impacts of future climate change in ocean mixing should be viewed with caution, at least regionally, by focusing on the detailed changes of the governing mechanisms.

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Recent changes in the summer monsoon circulation and their impact on dynamics and thermodynamics of the Arabian Sea

Cited by 19 publications

References 39 publications

Annihilation of the Somali upwelling system during summer monsoon

Annihilation of the Somali upwelling system during summer monsoon

Indian Ocean Warming

Oceanic Mixing over the Northern Arabian Sea in a Warming Scenario: Tug of War between Wind and Buoyancy Forces

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