Abstract
MITgcm is configured in a realistic situation to study the inter-seasonal variability of internal waves (IWs) in the western Bay of Bengal. Monthly climatology of the density fields from WOA09, modified ETOPO2 topography and barotropic tidal forcing are feed to the model for simulating IWs. The preliminary objective of the study is to identify IWs through the stratification and topographic configuration that support IWs. In this context numerical experiments are performed for January, April, July and October representing the winter, pre-monsoon, summer monsoon and post-monsoon, respectively, and analyses are made extensively over the western Bay of Bengal. Mixing caused by density overturning and shear instability is studied at the Gopalpur cross section for all seasons. The density time series are subjected to spectral analysis to find the energy associated with IWs of semi-diurnal frequency. Analysis depicts that the spectral estimates are high in the concave coastline pockets in the southern part and over a broader region on the shelf slope in the northern part. October shows higher estimates in response to highly stratified waters. Several cross sections are analyzed to obtain the spectral energy extent over the shelf slope. It is noticed in October that the peak estimate is within the shelf for shelf angles greater than 0.12° and it falls outside the shelf for shelf angles less than 0.12°.
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Adcroft A, Hill C, Marshall J (1997) Representation of topography by shaved cells in a height coordinate ocean model. Mon Weather Rev 125(9):2293–2315. doi:10.1175/1520-0493(1997)125%3C2293:rotbsc%3E2.0.co;2
Babu SV, Rao AD (2011) Mixing in the surface layers in association with internal waves during winter in the northwestern Bay of Bengal. Nat Hazards 57(3):551–562. doi:10.1007/s11069-010-9607-5
Gargettt AE, Hughes BA (1972) On the interaction of surface and internal waves. J Fluid Mech 52:179–191. doi:10.1017/s0022112072003027
Guo C, Chen X, Vlasenko V, Stashchuk N (2011) Numerical investigation of internal solitary waves from the luzon strait: generation process, mechanism and three-dimensional effects. Ocean Model 38(3–4):203–216. doi:10.1016/j.ocemod.2011.03.002
Haury LR, Briscoe MG, Orr MH (1979) Tidally generated internal wave packets in Massachusetts bay. Nature 278(5702):312–317. doi:10.1038/278312a0
Holligan PM, Pingree RD, Mardell GT (1985) Oceanic solitons, nutrient pulses and phytoplankton growth. Nature 314(6009):348–350. doi:10.1038/314348a0
Holloway PE, Merrifield MA (2003) On the spring-neap variability and age of the internal tide at the Hawaiian ridge. J Geophys Res 108(C4):3126. doi:10.1029/2002jc001486
Kang D, Fringer O (2011) Energetics of barotropic and baroclinic tides in the Monterey bay area. J Phys Oceanogr 42(2):272–290. doi:10.1175/jpo-d-11-039.1
Khatiwala S (2003) Generation of internal tides in an ocean of finite depth: analytical and numerical calculations. Deep Sea Res Part 1 Oceanogr Res Pap 50(1):3–21. doi:10.1016/s0967-0637(02)00132-2
Kurkina OE, Talipova TG (2011) Huge internal waves in the vicinity of the spitsbergen island (barents sea). Nat Hazards Earth Syst Sci 11:981–986. doi:10.5194/nhess-11-981-2011
Marshall J, Adcroft A, Hill C, Perelman L, Heisey C (1997) A finite-volume, incompressible navier stokes model for studies of the ocean on parallel computers. J Geophys Res 102(C3):5753–5766. doi:10.1029/96jc02775
Merrifield MA, Holloway PE (2002) Model estimates of M2 internal tide energetics at the Hawaiian ridge. J Geophys Res 107(C8):5-1–5-12. doi:10.1029/2001jc000996
Orlanski I (1976) A simple boundary condition for unbounded hyperbolic flows. J Comput Phys 21(3):251–269. doi:10.1016/0021-9991(76)90023-1
Pradhan H, Rao AD, Joshi M (2015a) Neap—spring variability of internal waves over the shelf-slope along western Bay of Bengal associated with local stratification. Nat Hazards. doi:10.1007/s11069-015-2027-9
Pradhan H, Rao AD, Mohanty S (2015b) Generation of internal tides: an interaction of tides with variable topography and coastal geometry. Ocean Sci J 50(2):183–194. doi:10.1007/s12601-015-0014-4
Rao AD, Babu SV, Prasad KVSR, RamanaMurty TV, Sadhuram Y, Mahapatra DK (2010) Investigation of the generation and propagation of low frequency internal waves: a case study for the east coast of India. Estuar Coast Shelf Sci 88(1):143–152. doi:10.1016/j.ecss.2010.03.010
Vlasenko V, Stashchuk N (2007) Three-dimensional shoaling of large-amplitude internal waves. J Geophys Res 112(C11):C11018. doi:10.1029/2007jc004107
Acknowledgments
The authors are thankful to the Naval Research Board (NRB), Government of India, for the financial support for carrying out this study. The valuable suggestions and support of Prof. B. S. R. Reddy for preparation of this paper are gratefully acknowledged. The first author also appreciates the financial support of CSIR, New Delhi, in the form of his research fellowship.
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Pradhan, H.K., Rao, A.D. & Mohanty, S. Inter-seasonal variability of internal tides in the western Bay of Bengal. Nat Hazards 84, 809–820 (2016). https://doi.org/10.1007/s11069-016-2459-x
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DOI: https://doi.org/10.1007/s11069-016-2459-x