Ocean Dynamics

, Volume 65, Issue 2, pp 173–186 | Cite as

Observed year-to-year sea surface salinity variability in the Bay of Bengal during the 2009–2014 period

  • Akurathi Venkata Sai Chaitanya
  • Fabien Durand
  • Simi Mathew
  • Vissa Venkata Gopalakrishna
  • Fabrice Papa
  • Matthieu Lengaigne
  • Jerome Vialard
  • Chanda Kranthikumar
  • R. Venkatesan


The present study describes the observed sea surface salinity (SSS) interannual variability in the Bay of Bengal over the 2009–2014 period. It is based on an original compilation of all available in situ SSS observations in that region, assembled in a 2°-resolution trimonthly gridded field. We find that year-to-year SSS variability is particularly strong in the north-eastern part of the bay. Over recent years, this variability takes the form of two successive and opposite phases: a saltening phase from mid-2009 to late 2010, immediately followed by a freshening phase from late 2010 to late 2011. The typical magnitude of each anomalous spell is about one in the practical salinity scale, making this area one of the most variable of the tropical oceans at interannual timescales. A simple mixed-layer salt budget indicates that year-to-year large-scale SSS variability in the Northern Bay of Bengal is primarily driven by freshwater flux variability with a correlation of 0.68, with rather independent contributions from precipitation and river run-off. The oceanic surface circulation variability contributes less systematically to the large-scale SSS evolution in the Northern Bay of Bengal over the entire record with a correlation of 0.13, despite a strong contribution at times, in particular, during the 2011 positive Indian Ocean Dipole (IOD) freshening.


SSS Bay of Bengal Argo Ganges Brahmaputra IOD 



We thank the three anonymous reviewers for their constructive comments on our paper. XCTD and bucket salinity observations are supported by the Ministry of Earth Sciences, through the Indian National Center for Ocean Information Services, Hyderabad, India. We thank the numerous people who spent a long time at sea collecting the salinity observations. Thermosalinograph data were collected and processed by the French SSS Observation Service ( We sincerely thank the team efforts of NIOT technical and scientific staff for providing continuous data from the OMNI moorings. We are thankful to Argo and RAMA programmes for making their salinity data available to all. FD, FP, ML and JV are funded by Institut de Recherche pour le Développement (IRD). Part of this work was done when CAVS and FD visited the Indo-French Cell for Water Sciences (Joint International Laboratory IRD-IISc, Bangalore, India). Support from this laboratory is gratefully acknowledged. We acknowledge constructive comments by Debasis Sengupta. This is CSIR-NIO contribution No. 5689


  1. Akhil VP, Durand F, Lengaigne M, Vialard J, Keerthi MG, Gopalakrishna VV, Deltel C, Papa F, de Boyer MC (2014) A modeling study of the processes of surface salinity seasonal cycle in the Bay of Bengal. J Geophys Res-Oceans 119:3926–3947. doi: 10.1002/2013JC009632 CrossRefGoogle Scholar
  2. Alory G, Maes C, Delcroix T, Reul N, Illig S (2012) Seasonal dynamicsof sea surface salinity off Panama: the far Eastern Pacific Fresh Pool. J Geophys Res 117(C04028). doi: 10.1029/2011JC007802
  3. Benshila R, Durand F, Masson S, Bourdalle-Badie R, de Boyer MC, Papa F, Madec G (2014) The upper Bay of Bengal salinity structure in a high-resolution model. Ocean Model 74:36–52CrossRefGoogle Scholar
  4. Bonjean F, Lagerloef GSE (2002) Diagnostic model and analysis of the surface currents in the tropical pacific ocean. J Phys Oceanogr 32(10):2938–2954CrossRefGoogle Scholar
  5. Chaitanya A V S, Lengaigne M, Vialard J, Gopalakrishna VV, Durand F, Kranthikumar C, Amritash S, Suneel V, Papa F, Ravichandran M (2014) Salinity measurements collected by fishermen reveal a “river in the sea” flowing along the east coast of India. Bull Am Meteorol Soc., in pressGoogle Scholar
  6. Chatterjee A, Shankar D, Shenoi SSC, Reddy GV, Michael GS, Ravichandran M, Gopalakrishna VV, Rama Rao EP, UdayaBhaskar TVS, Sanjeevan VN (2012) A new atlas of temperature and salinity for the north Indian ocean. J Hydrol Earth Syst Sci 121(3):559–593CrossRefGoogle Scholar
  7. Da-Allada C Y, Alory G, du Penhoat Y, Kestenare E, Durand F, Hounkonnou N M (2013) Seasonal mixed-layer salinity balance in the tropical Atlantic Ocean: mean state and seasonal cycle. J Geophys Res 118. doi: 10.1029/2012JC008357
  8. de Boyer MC, Madec G, Fischer AS, Lazar A, Iudicone D (2004) Mixed layer depth over the global ocean: an examination of profile data and a profile-based climatology. J Geophys Res 109(C12003). doi: 10.1029/2004JC002378
  9. de Boyer MC, Mignot CJ, Lazar A, Cravatte S (2007) Control of salinity on the mixed layer depth in the world ocean: 1. General description. J Geophys Res 112:C06011. doi: 10.1029/2006JC003953 Google Scholar
  10. de Boyer MC, Durand F, Bourdallé-Badie R, Blanke B (2014) Barrier layer in the Arabian Sea during summer monsoon. Ocean Dyn. doi: 10.1007/s10236-014-0716-7 Google Scholar
  11. Dee DP et al (2011) The ERA-interim reanalysis: configuration and performance of the data assimilation system. Q J R Meteorol Soc 137:553–597. doi: 10.1002/qj.828 CrossRefGoogle Scholar
  12. Delcroix T, McPhaden MJ, Dessier A, Gouriou Y (2005) Time and space scales for sea surface salinity in the tropical oceans. Deep Sea Res Part I 52(5):787–813. doi: 10.1016/j.dsr.2004.11.012 CrossRefGoogle Scholar
  13. Durand F, Shankar D, Birol F, Shenoi SSC (2009) Spatiotemporal structure of the east India coastal current from satellite altimetry. J Geophys Res 114, C02013. doi: 10.1029/2008JC004807 Google Scholar
  14. Durand F, Papa F, Rahman A, Bala SK (2011) Impact of Ganges–Brahmaputra interannual discharge variations on Bay of Bengal salinity and temperature during 1992–1999 period. J Earth Syst Sci 120:859–872CrossRefGoogle Scholar
  15. Durand F, Alory G, Dussin R, Reul N (2013) SMOS reveals the signature of Indian Ocean Dipole events. Ocean Dyn. doi: 10.1007/s10236-013-0660-y Google Scholar
  16. Furuichi T, Win Z, Wasson RJ (2009) Discharge and suspended sediment transport in the Ayeyarwady River, Myanmar: centennial and decadal changes. Hydrol Process 23:1631–1641. doi: 10.1002/hyp.7295 CrossRefGoogle Scholar
  17. Gadgil S (2003) The Indian monsoon and its variability. Annu Rev Earth Planet Sci 31:429–467CrossRefGoogle Scholar
  18. Gadgil S, Joseph PV, Joshi NV (1984) Ocean–atmosphere coupling over monsoonal regions. Nature 312:141–143CrossRefGoogle Scholar
  19. Girishkumar M S, Ravichandran M, McPhaden MJ (2013) Temperature inversions and their influence on themixed layer heat budget during the winters of 2006–2007 and 2007–2008 in the Bay of Bengal. J Geophys Res 118. doi: 10.1002/jgrc.20192
  20. Han W, McCreary JP, Kohler KE (2001) Influence of precipitation minus evaporation and Bay of Bengal rivers on dynamics, thermodynamics, and mixed layer physics in the upper Indian ocean. J Geophys Res 106(C4):6895–6916CrossRefGoogle Scholar
  21. Horii T, Ueki I, Ando K, Mizuno K (2013) Eastern Indian Ocean warming associated with the negative Indian Ocean dipole: a case study of the 2010 event. J Geophys Res 118:536–549. doi: 10.1002/jgrc.20071 CrossRefGoogle Scholar
  22. Huffman GJ, Adler RF, Bolvin DT, Gu GJ, Nelkin EJ, Bowman KP, Hong Y, Stocker EF, Wolff DB (2007) The TRMM multisatellite precipitation analysis (TMPA): quasi-global, multiyear, combined-sensor precipitation estimates at fine scales. J Hydrometeorol 8(1):38–55CrossRefGoogle Scholar
  23. Jensen TG (2007) Wind-driven response of the northern Indian Ocean to climate extremes. J Clim 20:2978–2993. doi: 10.1175/JCLI4150.1 CrossRefGoogle Scholar
  24. Jian J, Webster PJ, Hoyos CD (2009) Large-scale controls on Ganges and Brahmaputra river discharge on intraseasonal and seasonal time-scales. Q J R Meteorol Soc 135:353–370. doi: 10.1002/qj.384 CrossRefGoogle Scholar
  25. Lee T, Fukumori I, Tang B (2004) Temperature advection: internal versus external processes. J Phys Oceanogr 34:1936–1944CrossRefGoogle Scholar
  26. McPhaden MJ, Meyers G, Ando K, Masumoto Y, Murty VSN, Ravichandran M, Syamsudin F, Vialard J, Yu L, Yu W (2009) RAMA: the research moored array for African-Asian-Australian monsoon analysis and prediction. Bull Am Meteorol Soc 90:459–480CrossRefGoogle Scholar
  27. Mujumdar M, Preethi B, Sabin TP, Ashok K, Saeed S, Pai DS, Krishnan R (2012) The Asian summer monsoon response to the La Niña event of 2010. Meteorol Appl 19:216–225CrossRefGoogle Scholar
  28. Neetu S, Lengaigne M, Vincent EM, Vialard J, Madec G, Samson G, Ramesh Kumar MR, Durand F (2012) Influence of upper-ocean stratification on tropical cyclone-induced surface cooling in the Bay of Bengal. J Geophys Res 117(C12020). doi: 10.1029/2012JC008433
  29. Papa F, Durand F, Rossow WB, Rahman A Bala SK (2010) Satellite altimeter-derived monthly discharge of the Ganga-Brahmaputra river and its seasonal to interannual variations from 1993 to 2008. J Geophys Res, 115(C12013). doi: 10.1029/2009JC006075
  30. Papa F, Bala SK, Pandey RK, Durand F, Gopalakrishna VV, Rahman A, Rossow WB (2012) Ganga–Brahmaputra river discharge from Jason-2 radar altimetry:an update to the long-term satellite-derived estimates of continentalfreshwater forcing flux into the Bay of Bengal. J Geophys Res 117(C11021). doi: 10.1029/2012JC008158
  31. Parampil SR, Gera A, Ravichandran M, Sengupta D (2010) Intraseasonal response of mixed layer temperature and salinity in the Bay ofBengal to heat and freshwater flux. J Geophys Res 115(C0500). doi: 10.1029/2009JC005790
  32. Praveen Kumar B, Vialard J, Lengaigne M, Murty VSN, McPhaden MJ (2012) TropFlux: air-sea fluxes for the global tropical oceans - description and evaluation. Clim Dyn 38:1521–1543. doi: 10.1007/s00382-011-1115-0 CrossRefGoogle Scholar
  33. Rao RR, Sivakumar R (2003) Seasonal variability of sea surface salinity and salt budget of the mixed layer of the north Indian Ocean. J Geophys Res 108. doi: 10.1029/2001JC000907
  34. Rao SA, Gopalakrishna VV, Shetye SR, Yamagata T (2002a) Why were cool SST anomalies absent in the Bay of Bengal during the 1997 Indian Ocean Dipole event ? Geophys Res Lett 29(0). doi: 10.1029/2001/GL014645
  35. Rao SA, Behera SK, Masumoto Y, Yamagata T (2002b) Interannual subsurface variability in the tropical Indian Ocean with a special emphasis on the Indian Ocean Dipole. Deep-Sea Res II(49):1549–1572Google Scholar
  36. Rao SA, et al. (2011) Modulation of SST, SSS over northern Bay of Bengal on ISO time scale. J Geophys Res 116. doi: 10.1029/2010JC006804
  37. Reverdin G, Cadet DL, Gutzler D (1986) Interannual displacements of convection and surface circulation over the equatorial Indian Ocean. QJRMS 112(471):43–67CrossRefGoogle Scholar
  38. Roemmich D, Johnson GC, Riser S, Davis R, Gilson J, Owens WB, Garzoli SL, Schmid C, Ignaszewski M (2009) The Argo program: observing the global ocean with profiling floats. Oceanography 22(2):34–43. doi: 10.5670/oceanog.2009.36 CrossRefGoogle Scholar
  39. Saji NH, Goswami BN, Vinayachandran PN, Yamagata T (1999) A dipole mode in the tropical Indian ocean. Nature 401:360–363Google Scholar
  40. Sengupta D, Bharath Raj GN, Shenoi SSC (2006) Surface freshwater from Bay of Bengal runoff and Indonesian throughflow in the tropical Indian Ocean. Geophys Res Lett 33(L22609). doi: 10.1029/2006GL027573
  41. Sengupta D, Bharath Raj GN, Anitha DS (2008) Cyclone-induced mixing does not cool SST in the post-monsoon north Bay of Bengal. Atmos Sci Let 9:1–6. doi: 10.1002/asi.162 CrossRefGoogle Scholar
  42. Shenoi SSC, Shankar D, Shetye SR (2002) Differences in heat budgets of the near-surface Arabien Sea and Bay of Bengal: implications for the summer monsoon. J Geophys Res 107(C6). doi: 10.1029/2000JC000679
  43. Shesu RV, UdayaBhaskar TVS, Pattabhi Rama Rao E, Devender R, HemasundarRao T (2013) Open source architecture for web-based oceanographic data services. Data Sci J 12:47–55CrossRefGoogle Scholar
  44. Subrahmanyam B, Grunseich G, Nyadjro ES (2013) Preliminary SMOS salinity measurements and validation in the Indian Ocean. IEEE Trans Geosci Remote Sens 51(1):19–27CrossRefGoogle Scholar
  45. Tang W, Yueh SH, Fore AG, Hayashi A (2014) Validation of Aquarius sea surface salinity with in situ measurements from Argo floats and moored buoys. J Geophys Res-Oceans 119:6171–6189. doi: 10.1002/2014JC010101 CrossRefGoogle Scholar
  46. Tanguy Y, Arnault S, Lattes P (2010) Isothermal, mixed, and barrier layers in the subtropical and tropical Atlantic Ocean during the ARAMIS experiment. Deep Sea Res I 57(4):501–517. doi: 10.1016/j.dsr.2009.12.012 CrossRefGoogle Scholar
  47. Thompson B, Gnanaseelan C, Salvekar PS (2006) Variability in the Indian Ocean circulation and salinity and its impact on SST anomalies during dipole events. J Mar Res 64:853–880CrossRefGoogle Scholar
  48. Venkatesan R, Arul Muthiah M, Ramesh K, Ramasundaram S, Sundar R, Atmanand MA (2013) Satellite communication systems for ocean observational platforms: societal importance and challenges. J Ocean Technol 8(3):47–73Google Scholar
  49. Vinayachandran PN, Nanjundiah RS (2009) Indian Ocean sea surface salinity variations in a coupled model. Clim Dyn. doi: 10.1007/s00382-008-0511-6 Google Scholar
  50. Vinayachandran, PN, Neema CP, Mathew S, RemyaR (2012) Mechanisms of summer intraseasonal sea surface temperature oscillations in the Bay of Bengal. J Geophys Res 117(C01005). doi: 10.1029/2011JC007433
  51. Webster PJ, Moore AM, Loschnigg JP, Leben RR (1999) Coupled ocean–atmosphere dynamics in the Indian Ocean during 1997–98. Nature 401:356–360. doi: 10.1038/43848 CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Akurathi Venkata Sai Chaitanya
    • 1
  • Fabien Durand
    • 1
    • 2
  • Simi Mathew
    • 4
  • Vissa Venkata Gopalakrishna
    • 1
  • Fabrice Papa
    • 2
    • 3
  • Matthieu Lengaigne
    • 5
    • 6
  • Jerome Vialard
    • 5
  • Chanda Kranthikumar
    • 1
  • R. Venkatesan
    • 4
  1. 1.CSIR/National Institute of Oceanography (NIO)GoaIndia
  2. 2.IRD/Laboratoire d’études en Géophysique et Océanographie Spatiales (LEGOS)ToulouseFrance
  3. 3.Indo-French Cell for Water Sciences, IISc-NIO-IITM–IRD Joint International Laboratory, IIScBangaloreIndia
  4. 4.National Institute of Ocean Technology (NIOT)ChennaiIndia
  5. 5.Sorbonne Universités, UPMC Univ Paris 06, UMR 7159, LOCEANParisFrance
  6. 6.Indo-French Cell for Water SciencesNational Institute of OceanographyDona PaulaIndia

Personalised recommendations