Sea Level Variability and Trends in the North Indian Ocean
Sea level rise (over the globe as well as over the Indian Ocean) is one of the most serious issues considering its potential threat to the low-lying coastal areas and coastal population. TOPEX/Poseidon altimeter observations suggest a sea level rise over the Arabian Sea and Bay of Bengal. The rate of sea level rise over the Arabian Sea is about 0.5–3 mm/year, whereas over the Bay of Bengal, it is 0.75–6 mm/year. Major contributors to these changes in the Indian Ocean are steric effect and short-term climate variability such as El Niño–Southern Oscillation (ENSO) and the Indian Ocean Dipole. This affirms that sea level trends over north Indian Ocean get modulated by inter-annual and decadal scale natural climate variability. The inter-annual variability is stronger than decadal variability, which in turn is stronger than the long-term sea level trend. Sea level change in the Indian Ocean is about 1.5 mm/year in the past sixty years or so, whereas the global sea level trends are a bit higher. This picture completely changed in the recent years with very significant sea level rise in the Indian Ocean and is comparable to the global trends. A future projection for the sea level rise over the Indian Ocean based on the highest emission scenario is 40–67 cm for the averaged span of 2071–2100 with the base period of 1921–1990.
We thank Director, IITM, and MoES for support. PSMSL and AVISO are acknowledged for providing tide gauges and altimeter-merged observations on their Web site. Some of the figures are prepared using Ferret. PAOS-Colorado is acknowledged for providing wavelet software online.
- Aparna, S. G., McCreary, J. P., Shankar, D. and Vinayachandran, P. N. (2012), Signatures of Indian Ocean Dipole and El Nino–Southern Oscillation events in sea level variations in the Bay of Bengal. J. Geophys. Res. C, 117, C10012, 13.Google Scholar
- Cabanes, C., A. Cazenave, and C. Le Provost (2001a), Sea level change from TOPEXPoseidon altimetry for 1993 –1999 and possible warming of the southern oceans, Geophys. Res. Lett., 28(1), 9–12.Google Scholar
- Cabanes, C., A. Cazenave, and C. Le Provost (2001b), Sea level rise during past 40 years determined from satellite and in situ observations, Science, 294, 840–842. Cazenave, A., K. Dominh, M. C. Gennero, and B. Ferret (1998), Global mean sea level changes observed by TOPEX-Poseidon and ERS-1, Phys. Chem. Earth, 23(9–10), 1069– 1075.Google Scholar
- Cazenave, A., and R. S. Nerem (2004), Present-day sea level change: Observations and causes, Rev. Geophys., 42, RG3001, doi: 10.1029/2003RG000139.
- Cazenave, A., K. Dominh, F. Ponchaut, L. Soudarin, J.-F.Cretaux, and C. Le Provost (1999), Sea level changes from TOPEXPoseidon altimetry and tide gauge, and vertical crustal motions from DORIS, Geophys. Res. Lett., 26(14), 2077–2080.Google Scholar
- Chelton, D. B., J. C. Ries, B. J. Haines, L.-L.Fu, and P. S. Callahan (2001), Satellite altimetry, in Satellite Altimetry and Earth Sciences, edited by L.-L. Fu and A. Cazenave, pp. 1– 131, Academic, San Diego, Calif.Google Scholar
- Christensen, E. J., et al. (1994), Calibration of TOPEX/Poseidon at Platform Harvest, J. Geophys. Res., 99(C12), 24,465–24,486.Google Scholar
- Church, J. A., Gregory, J. M., Huybrechts, Kuhn, M., Lambeck, K., Nhuan, M. T., Qin, D. and Woodworth, P. L.(2001), Changes in sea level. In Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University, Press, Cambridge, UK, pp. 639–693.Google Scholar
- Church J A, and White N J (2011), Sea-Level Rise from the Late 19th to the Early 21st Century, Surv Geophys (2011) 32:585–602Google Scholar
- Church J A, White N J and Hunter J R (2006), Sea-level rise at tropical Pacific and Indian Ocean islands; Global and Planetary Change, 53 155–168.Google Scholar
- Douglas, B. C. (2001), Sea level change in the era of the recording tide gauge, in Sea Level Rise: History and Consequences, Int. Geophys. Ser., vol. 75, edited by B. C. Douglas, M. S. Kearney, and S. P. Leatherman, chap. 3, pp. 37 – 64, Elsevier, New York.Google Scholar
- Han, W. et al.(2010), Patterns of Indian Ocean sea-level change in a warming climate. Nature Geoscience, 3, 546–550; DOI: 10.1338/NGEO 901.
- Kusche, J., B. Uebbing, R. Rietbroek, C. K. Shum, and Z. H. Khan (2016), Sea level budget in the Bay of Bengal (2002–2014) from GRACE and altimetry, J. Geophys. Res. Oceans, 121, doi: 10.1002/2015JC011471.
- Mitchum, G. T. (1994), Comparison of TOPEX sea surface heights and tide gauge sea levels, J. Geophys. Res., 99(C12), 24,541– 24,554.Google Scholar
- Nerem, R. S., and G. T. Mitchum (2002). ”Estimates of vertical crustal motion derived from differences of TOPEX/POSEIDON and tide gauge sea level measurements.” Geophysical Research Letters 29: 40-1Google Scholar
- Nicholls, R.J., P.P. Wong, V.R. Burkett, J.O. Codignotto, J.E. Hay, R.F. McLean, S. Ragoonaden and C.D. Woodroffe, (2007) Coastal systems and low-lying areas. Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson, Eds., Cambridge University Press, Cambridge, UK, 315-356.Google Scholar
- Nidheesh, A. G., Lengaigne, M., Vialard, J., Unnikrishnan, A. S. and Dayan, H.(2013), Decadal and long-term sea level variability in the tropical Indo-Pacific Ocean. Climate Dyn., 41(2), 381–402.Google Scholar
- Parekh A.(2010), A Note on Sea Level Rise, Int. J. Earth Sciences and Engineering,,03, CAS Ref. No.: 172238.Google Scholar
- Palanisamy, H., Cazenave, A., Meyssignac, B., Soudarin, L., Wöppelmann, G. and Becker, M. (2014) Regional sea level variability, total relative sea level rise and its impacts on islands and coastal zones of Indian Ocean over the last sixty years. Global Planet. Change, doi: 10.1016/j.gloplacha.2014.02.001.
- Rahul S, C. Gnanaseelan (2015) Can large scale surface circulation changes modulate the sea surface warming pattern in the Tropical Indian Ocean?. Clim Dyn 10.1007/s00382-015-2790-z
- Rietbroek R, Brunnabend SE, Kusche J, Schröter J (2012) Resolving sea level contributions by identifying fingerprints in time-variable gravity and altimetry. J Geodyn 59:72–81.Google Scholar
- Sayantani Ojha, C. Gnanaseelan (2015) Tropical Indian Ocean subsurface temperature variability and the forcing mechanisms, Clim Dyn 44:2447–2462.Google Scholar
- Shankar, D. et al. (2010), Minima of interannual sea-level variability in the Indian Ocean. Prog. Oceanogr., 84(3–4), 225–241.Google Scholar
- Shetye, S.R.,Gouveia, A.D, Pathak, M.C.(1990) Vulnerability of the Indian coastal region to damage from sea level rise. Current Science, Vol.59; 152-156Google Scholar
- Sreenivas, P., Gnanaseelan, C., and Prasad, K.V.S.R., (2012), Influence of El Niño and Indian Ocean Dipole on sea level variability in the Bay of Bengal, Global and Planetary Change, 80-81, 215-225, doi: 10.1016/j.gloplacha.2011.11.
- Tapley, B. D. (1994), et al., Precision orbit determination for TOPEX/POSEIDON, J. Geophys. Res., 99(C12), 24,383 – 24,404.Google Scholar
- Torrence, C., G. Compo (1998), A practical guide to wavelet analysis, Bull. Am. Meteorol. Soc., 79,61–78.Google Scholar
- Unnikrishnan, A. S., K. Rupa Kumar, Sharon E. Fernandes, G. S. Michael and S. K. Patwardhan (2006), Sea level changes along the Indian coast: Observations and projections, Curr. Sci.,, Vol. 90, 362-368.Google Scholar
- Unnikrishnan, A. S. and Shankar, D. (2007), Are sea-level-rise trends along the north Indian Ocean coasts consistent with global estimates? Global Planet. Change, 57, 301–307.Google Scholar
- Unnikrishnan A. S., A. G. Nidheesh and M. Lengaigne (2015), Sea-level-rise trends off the Indian coasts during the last two decades,, Curr.Sci., Vol. 108, 966-971.Google Scholar
- Unnikrishnan, A.S.; RameshKumar, M.R.; Sindhu, B. (2011) Tropical cyclones in the Bay of Bengal and extreme sea-level projections along the east coast of India in a future climate scenario, Curr. Sci.: 101(3); 327-331.Google Scholar
- Woodworth, P. L., and R. Player (2003), The Permanent Service for Mean Sea Level: An update to the 21st century, J. Coastal Res., 19, 287–295.Google Scholar