The impact of northern Indian Ocean rivers on the Bay of Bengal using NEMO global ocean model

Abstract

The effect of river runoff over the northern Indian Ocean (NIO) especially over the Bay of Bengal (BoB) has been studied using global Nucleus for European Modelling of the Ocean (NEMO). Two sensitivity experiments, with and without river runoff are conducted and the influence of river runoff on the Indian Ocean hydrography, stratification and circulation features are studied. It is found that due to river runoff surface salinity over the northern BoB decreases by more than 5 and the East India Coastal Current strengthens by 2 cm/s during post monsoon season. The fresh river water reaches up to 15°N in the BoB and is the main cause for low salinity there. Sea surface temperature in the northwestern BoB increases by more than 0.2°C due to the river runoff in summer monsoon while surface cooling upto 0.2°C is seen in north-west part of BoB in winter season. The seasonal mixed layer depth in the region is found to be dependent on river runoff. The effect of vertical shear and Brunt Vaisala frequency on stratification is also examined. The ocean water becomes highly stratified up to 3 035 m due to the river runoff. It is found that the energy required for mixing is high in the northern and coastal BoB.

References

  1. Akhil V P, Durand F, Lengaigne M, et al. 2014. A modeling study of the processes of surface salinity seasonal cycle in the Bay of Bengal. Journal of Geophysical Research: Oceans, 119(6): 3926–3947, doi: https://doi.org/10.1002/2013JC009632

    Google Scholar 

  2. Anitha G, Ravichandran M, Sayanna R. 2008. Surface buoyancy flux in Bay of Bengal and Arabian Sea. Annales Geophysicae, 26(3): 395–400, doi: https://doi.org/10.5194/angeo-26-395-2008

    Article  Google Scholar 

  3. Balmaseda M A, Mogensen K, Weaver A T. 2013. Evaluation of the ECMWF ocean reanalysis system ORAS4. Quarterly Journal of the Royal Meteorological Society, 139(674): 1132–1161, doi: https://doi.org/10.1002/qj.2063

    Article  Google Scholar 

  4. Behara A, Vinayachandran P N. 2016. An OGCM study of the impact of rain and river water forcing on the Bay of Bengal. Journal of Geophysical Research: Oceans, 121(4): 2425–2446, doi: https://doi.org/10.1002/2015JC011325

    Google Scholar 

  5. Bonjean F, Lagerloef G S E. 2002. Diagnostic model and analysis of the surface currents in the tropical Pacific Ocean. Journal of Physical Oceanography, 32(10): 2938–2954, doi: https://doi.org/10.1175/1520-0485(2002)032<2938:DMAAOT>2.0.CO;2

    Article  Google Scholar 

  6. Callaghan A H, Ward B, Vialard J. 2014. Influence of surface forcing on near-surface and mixing layer turbulence in the tropical Indian Ocean. Deep Sea Research Part I: Oceanographic Research Papers, 94: 107–123, doi: https://doi.org/10.1016/j.dsr.2014.08.009

    Article  Google Scholar 

  7. Chamarthi S P, Ram P S, Josyula L. 2008. Effect of river discharge on Bay of Bengal circulation. Marine Geodesy, 31(3): 160–168, doi: https://doi.org/10.1080/01490410802265476

    Article  Google Scholar 

  8. Chowdary J S, Srinivas G, Fousiya T S, et al. 2016. Representation of Bay of Bengal upper-ocean salinity in general circulation models. Oceanography, 29(2): 38–49, doi: https://doi.org/10.5670/oceanog.2016.37

    Article  Google Scholar 

  9. Da-Allada C Y, Gaillard F, Kolodziejczyk N. 2015. Mixed-layer salinity budget in the tropical Indian Ocean: seasonal cycle based only on observations. Ocean Dynamics, 65(6): 845–857, doi: https://doi.org/10.1007/s10236-015-0837-7

    Article  Google Scholar 

  10. Dai Aiguo, Qian Taotao, Trenberth K E, et al. 2009. Changes in continental freshwater discharge from 1948 to 2004. Journal of Climate, 22(10): 2773–2792, doi: https://doi.org/10.1175/2008JCLI2592.1

    Article  Google Scholar 

  11. de Boyer Montégut C, Mignot J, Lazar A, et al. 2007. Control of salinity on the mixed layer depth in the world ocean: 1. General description. Journal of Geophysical Research: Oceans, 112(C6): C06011

    Article  Google Scholar 

  12. Durand F, Papa F, Rahman A, et al. 2011. Impact of Ganges-Brahmaputra interannual discharge variations on Bay of Bengal salinity and temperature during 1992–1999 period. Journal of Earth System Science, 120(5): 859–872, doi: https://doi.org/10.1007/s12040-011-0118-x

    Article  Google Scholar 

  13. Gan Jianping, Li Li, Wang Dongxia, et al. 2009. Interaction of a river plume with coastal upwelling in the northeastern South China Sea. Continental Shelf Research, 29(4):, doi: https://doi.org/10.1016/j.csr.2008.12.002

    Article  Google Scholar 

  14. Gaspar P, Grégoris Y, Lefevre J M. 1990. A simple eddy kinetic energy model for simulations of the oceanic vertical mixing: Tests at station Papa and Long-Term Upper Ocean Study site. Journal of Geophysical Research: Oceans, 95(C9): 16179–16193, doi: https://doi.org/10.1029/JC095iC09p16179

    Article  Google Scholar 

  15. Gera A, Mitra A K, Mahapatra D K, et al. 2013. Sea surface height and upper ocean heat content variability in Bay of Bengal during contrasting Monsoons 2009 and 2010. NCMRWF research report, NMRF/RR/OCN-1/2013, 1–27

    Google Scholar 

  16. Gopalakrishna V V, Johnson Z, Salgaonkar G, et al. 2005. Observed variability of sea surface salinity and thermal inversions in the Lakshadweep Sea during contrast monsoons. Geophysical Research Letters, 32(18): L18605

    Article  Google Scholar 

  17. Gordon A L, Susanto R D, Vranes K. 2003. Cool Indonesian through-flow as a consequence of restricted surface layer flow. Nature, 425(6960): 824–828, doi: https://doi.org/10.1038/nature02038

    Article  Google Scholar 

  18. Halkides D J, Waliser D E, Lee T, et al. 2015. Quantifying the processes controlling intraseasonal mixed-layer temperature variability in the tropical Indian Ocean. Journal of Geophysical Research: Oceans, 120(2): 692–715, doi: https://doi.org/10.1002/2014JC010139

    Google Scholar 

  19. Harenduprakash L, Mitra A K. 1988. Vertical turbulent mass flux below the sea surface and air-sea interaction-monsoon region of the Indian Ocean. Deep Sea Research Part A. Oceanographic Research Papers, 35(3): 333–346, doi: https://doi.org/10.1016/0198-0149(88)90014-3

    Article  Google Scholar 

  20. Howden S D, Murtugudde R. 2001. Effects of river inputs into the Bay of Bengal. Journal of Geophysical Research: Oceans, 106(C9): 19825–19843, doi: https://doi.org/10.1029/2000JC000656

    Article  Google Scholar 

  21. Jana S, Gangopadhyay A, Chakraborty A. 2015. Impact of seasonal river input on the Bay of Bengal simulation. Continental Shelf Research, 104: 45–62, doi: https://doi.org/10.1016/j.csr.2015.05.001

    Article  Google Scholar 

  22. Jensen T G. 2001. Arabian Sea and Bay of Bengal exchange of salt and tracers in an ocean model. Geophysical Research Letters, 28(20): 3967–3970, doi: https://doi.org/10.1029/2001GL013422

    Article  Google Scholar 

  23. Large W G, Yeager S G. 2009. The global climatology of an interannually varying air-sea flux data set. Climate Dynamics, 33(2–3): 341–364

    Article  Google Scholar 

  24. Madec G. 2012. NEMO-Team. Note du Pôle de modélisation, Institut Pierre-Simon Laplace (IPSL), France. NEMO ocean engine, 27

    Google Scholar 

  25. Mahapatra D K, Rao A D. 2017. Redistribution of low-salinity pools off east coast of India during southwest monsoon season. Estuarine, Coastal and Shelf Science, 184: 21–29, doi: https://doi.org/10.1016/j.ecss.2016.10.037

    Article  Google Scholar 

  26. Momin I M, Mitra A K, Mahapatra D K, et al. 2013. Indian Ocean simulation results from NEMO global ocean model. Indian Journal of Geo-Marine Sciences, 42(4): 425–430

    Google Scholar 

  27. Momin I M, Mitra A K, Mahapatra D K, et al. 2014. Impact of model resolutions on Indian Ocean simulations from Global NEMO Ocean Model. Indian Journal of Geo-Marine Sciences, 43(9): 1667–1674

    Google Scholar 

  28. Neetu S, Lengaigne M, Vincent E M, et al. 2012. Influence of upperocean stratification on tropical cyclone-induced surface cooling in the Bay of Bengal. Journal of Geophysical Research: Oceans, 117(C12): C12020

    Article  Google Scholar 

  29. Perigaud C, McCreary J P Jr, Zhang K Q. 2003. Impact of interannual rainfall anomalies on Indian Ocean salinity and temperature variability. Journal of Geophysical Research: Oceans, 108(C10): 3319, doi: https://doi.org/10.1029/2002JC001699

    Article  Google Scholar 

  30. Prasad T G. 1997. Annual and seasonal mean buoyancy fluxes for the tropical Indian Ocean. Current Science, 73(8): 667–674

    Google Scholar 

  31. Prasanna K S, Narvekar J, Kumar A, et al. 2004. Intrusion of the Bay of Bengal water into the Arabian Sea during winter monsoon and associated chemical and biological response. Geophysical Research Letters, 31(15): L15304, doi: https://doi.org/10.1029/2004GL020247

    Article  Google Scholar 

  32. Rao R R, Sivakumar R. 1999. On the possible mechanisms of the evolution of a mini-warm pool during the pre-summer monsoon season and the genesis of onset vortex in the South-Eastern Arabian Sea. Quarterly Journal of the Royal Meteorological Society, 125(555): 787–809, doi: https://doi.org/10.1002/qj.49712555503

    Article  Google Scholar 

  33. Rao R R, Sivakumar R. 2003. Seasonal variability of sea surface salinity and salt budget of the mixed layer of the north Indian Ocean. Journal of Geophysical Research: Oceans, 108(C1): 9–1–9–14

    Article  Google Scholar 

  34. Sengupta D, Ravichandran M. 2001. Oscillations of Bay of Bengal Sea surface temperature during the 1998 summer monsoon. Geophysical Research Letters, 28(10): 2033–2036, doi: https://doi.org/10.1029/2000GL012548

    Article  Google Scholar 

  35. Sengupta D, Ray P K, Bhat G S. 2002. Spring warming of the eastern Arabian Sea and Bay of Bengal from buoy data. Geophysical Research Letters, 29(15): 24–1–24–4, doi: https://doi.org/10.1029/2002GL015340

    Article  Google Scholar 

  36. Sengupta D, Bharath Raj G N, Shenoi S S C. 2006. Surface freshwater from Bay of Bengal runoff and Indonesian throughflow in the tropical Indian Ocean. Geophysical Research Letters, 33(22): L22609, doi: https://doi.org/10.1029/2006GL027573

    Article  Google Scholar 

  37. Sengupta D, Senan R, Goswami B N, et al. 2007. Intraseasonal variability of equatorial Indian Ocean zonal currents. Journal of Climate, 20(13): 3036–3055, doi: https://doi.org/10.1175/JCLI4166.1

    Article  Google Scholar 

  38. Shenoi S S C, Shankar D, Shetye S R. 2002. Differences in heat budgets of the near-surface Arabian Sea and Bay of Bengal: Implications for the summer monsoon. Journal of Geophysical Research: Oceans, 107(C6): 5–1–5–14

    Article  Google Scholar 

  39. Shetye S R, Gouveia A D, Shankar D, et al. 1996. Hydrography and circulation in the western Bay of Bengal during the northeast monsoon. Journal of Geophysical Research: Oceans, 101(C6): 14011–14025, doi: {rs10.1029/95JC03307 DOI }

    Article  Google Scholar 

  40. Shu Yeqiang, Wang Dongxiao, Zhu Jiang, et al. 2011. The 4-D structure of upwelling and Pearl River plume in the northern South China Sea during summer 2008 revealed by a data assimilation model. Ocean Modeling, 36(3–4)): 228–241

    Google Scholar 

  41. Shu Yeqiang, Chen Ju, Yao Jinglong, et al. 2014. Effects of the Pearl River plume on the vertical structure of coastal currents in the northern South China Sea during summer 2008. Ocean Dynamics, 64: 1743–1752, doi: https://doi.org/10.1007/s10236-014-0779-5

    Article  Google Scholar 

  42. Smyth W D, Moum J N. 2013. Marginal instability and deep cycle turbulence in the eastern equatorial Pacific Ocean. Geophysical Research Letters, 40(23): 6181–6185, doi: https://doi.org/10.1002/2013GL058403

    Article  Google Scholar 

  43. Srivastava A, Dwivedi S, Mishra A K. 2018. Investigating the role of air-sea forcing on the variability of hydrography, circulation, and mixed layer depth in the Arabian Sea and Bay of Bengal. Oceanologia, 60(2): 169–186, doi: https://doi.org/10.1016/j.oceano.2017.10.001

    Article  Google Scholar 

  44. Thomson R E, Fine I V. 2003. Estimating mixed layer depth from oceanic profile data. Journal of Atmospheric and Oceanic Technology, 20(2): 319–329, doi: https://doi.org/10.1175/1520-0426(2003)020<0319:EMLDFO>2.0.CO;2

    Article  Google Scholar 

  45. Varkey M J, Murty V S N, Suryanarayana A. 1996. Physical oceanography of the Bay of Bengal and Andaman Sea. Oceanography and Marine Biology: An Annual Review, 34: 1–70

    Google Scholar 

  46. Vinayachandran P N, Iizuka S, Yamagata T. 2002. Indian Ocean dipole mode events in an ocean general circulation model. Deep Sea Research Part II: Topical Studies in Oceanography, 49(7–8): 1573–1596

    Article  Google Scholar 

  47. Vinayachandran P N, Jahfer S, Nanjundiah R S. 2015. Impact of river runoff into the ocean on Indian summer monsoon. Environmental Research Letters, 10(5): 054008, doi: https://doi.org/10.1088/1748-9326/10/5/054008

    Article  Google Scholar 

  48. Weller R A, Fischer A S, Rudnick D L, et al. 2002. Moored observations of upper-ocean response to the monsoons in the Arabian Sea during 1994–1995. Deep Sea Research Part II: Topical Studies in Oceanography, 49(12): 2195–2230, doi: https://doi.org/10.1016/S0967-0645(02)00035-8

    Article  Google Scholar 

  49. Zweng M M, Reagan J R, Antonov J I, et al. 2013. World ocean atlas 2013. Volume 2: Salinity. Silver Spring, MD

    Google Scholar 

Download references

Acknowledgments

This study was done under MOES-NERC BoBBLE project. We also thank NCEP/NCAR, CORE 2, OSCAR and other data centres for providing reanalysis and observations data publicly for research purpose. OSCAR is generated by Earth Space Research (ESR) https://www.esr.org/research/oscar. We also express our thanks to Head NCMRWF for encouraging this study. We also thank the NEMO consortium for making the NEMO model code available.

Author information

Affiliations

Authors

Corresponding author

Correspondence to Atul Srivastava.

Additional information

Foundation item: MOES-NERC Bay of Bengal BLE project.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Srivastava, A., Gera, A., Momin, I.M. et al. The impact of northern Indian Ocean rivers on the Bay of Bengal using NEMO global ocean model. Acta Oceanol. Sin. 39, 45–55 (2020). https://doi.org/10.1007/s13131-020-1537-9

Download citation

Key words

  • Bay of Bengal
  • sea surface temperature
  • salinity
  • mixed layer depth
  • stratification