Characteristics of Tides in the Bay of Bengal

Sindhu, B.; Unnikrishnan, A.S.

doi:10.1080/01490419.2013.781088

Cited by 68 publications

(22 citation statements)

References 16 publications

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“…The harmonic analysis of astronomical tide provides us with 37 tidal constituents, among which the principal diurnal and semidiurnal constituents are tabulated in table S1. These values comply closely with those reported earlier by Unnikrishnan (1999) and Sindhu and Unnikrishnan (2013).…”

Section: Regionalized Design Rainfall ( R) and Storm-tide ( T) Scenariossupporting

confidence: 94%

Tide-rainfall flood quotient: an incisive measure of comprehending a region’s response to storm-tide and pluvial flooding

Mohanty

Sherly

Ghosh

et al. 2020

Environ. Res. Lett.

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It is undeniable that coastal regions worldwide are facing unprecedented damages from catastrophic floods attributable to storm-tide (tidal) and extreme rainfall (pluvial). For flood-risk assessment, although recognizing compound impact of these drivers is a conventional practice, the marginal/individual impacts cannot be overlooked. In this letter, we propose a new measure, Tide-Rainfall Flood Quotient (TRFQ), to quantify the driver-specific flood potential of a coastal region arising from storm-tide or rainfall. A set of inundation and hazard maps are derived through a series of numerical and hydrodynamic flood model simulations comprising of design rainfall and design storm-tide. These experiments are demonstrated on three different geographically diverse flood-affected coastal regions in India. The new measure throws light on existing knowledge gaps on the propensity of coastal flooding induced by the marginal/individual contribution of storm-tide and rainfall. It shall prove useful in rationalizing long-term flood management strategies customizable for storm-tide and pluvial dominated global coastal regions.

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Section: Regionalized Design Rainfall ( R) and Storm-tide ( T) Scenariossupporting

confidence: 94%

Tide-rainfall flood quotient: an incisive measure of comprehending a region’s response to storm-tide and pluvial flooding

Mohanty

Sherly

Ghosh

et al. 2020

Environ. Res. Lett.

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“…The M 2 harmonic constants are barely larger than the formal error estimate (Figure a), and the power spectrum is not visibly reduced by subtracting the stationary tide (Figure b). Tides in the region exceed 1 m at the coast [ Murty and Henry , ; Sindhu and Unnikrishnan , ], and significant interactions between tides and storm surges occur here [ Antony and Unnikrishnan , ]. It might be speculated that the tidal nonstationarity is caused by nonlinear interactions of the barotropic tide with nontidal processes; however, the power spectrum is very clearly peaked at

k_{M 2}

and suggests that quasi‐linear internal tides are responsible for the variability.…”

Section: Regional Examplesmentioning

confidence: 99%

Mapping the nonstationary internal tide with satellite altimetry

Zaron

2017

JGR Oceans

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Temporal variability of the internal tide has been inferred from the 23 year long combined records of the TOPEX/Poseidon, Jason‐1, and Jason‐2 satellite altimeters by combining harmonic analysis with an analysis of along‐track wavenumber spectra of sea‐surface height (SSH). Conventional harmonic analysis is first applied to estimate and remove the stationary components of the tide at each point along the reference ground tracks. The wavenumber spectrum of the residual SSH is then computed, and the variance in a neighborhood around the wavenumber of the mode‐1 baroclinic M2 tide is interpreted as the sum of noise, broadband nontidal processes, and the nonstationary tide. At many sites a bump in the spectrum associated with the internal tide is noted, and an empirical model for the noise and nontidal processes is used to estimate the nonstationary semidiurnal tidal variance. The results indicate a spatially inhomogeneous pattern of tidal variability. Nonstationary tides are larger than stationary tides throughout much of the equatorial Pacific and Indian Oceans.

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“…Semidiurnal M 2 is the largest tidal constituent in the BoB (Fig. 1b) followed by S 2 and their spatial variation is almost similar 18 . Therefore, we restricted the analysis only to M 2 internal tides in this paper.…”

Section: Resultsmentioning

confidence: 79%

“…4c). This is mainly due to the nearly same phase of the barotropic M 2 tide in the northern BoB18 . For example, the phase a) Barotrpic energy flux…”

mentioning

confidence: 74%

Intensification of tidally generated internal waves in the north-central Bay of Bengal

Jithin

Subeesh

Francis

et al. 2020

Sci Rep

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Flow of barotropic tidal currents over topographic features, such as continental slopes and submarine ridges, generates internal gravity waves at tidal periods known as internal tides. Amplitude of these waves are generally large near the generation regions. Analysis of Sea Surface Height (SSH) data, derived from satellite altimeter revealed the amplification of internal tides in the semidiurnal period in the north-central Bay of Bengal (BoB) (around 89  E, 16  N), which is about 450 km away from their generation sites. SSH signals found in the north-central BoB (~3 cm) were comparable to the maximum amplitudes (2.5 to 3.5 cm) observed near their potential generation sites in the BoB such as continental slopes in the head of the bay and Andaman-Nicobar (AN) Ridge. Simulations from a high-resolution regional ocean model also confirmed the presence of large internal tide amplitude in the north-central BoB. Our study revealed that convergence of internal tides, which were generated along the concaveshaped source (continental slopes in the head of the bay and the northern parts of AN Ridge), into its focal region caused their amplification in the north-central BoB. It was also found that internal tide energy dissipation rates in this focal region were about 10 times larger than those in other open ocean regions.Periodic flow of tidal currents over steep topography generates vertical oscillations of isopycnal surfaces in the stratified ocean. These internal oscillations propagate away as gravity waves, known as internal tides. Continental margins and submarine ridges are the main sources of this tidally-generated internal gravity waves in the ocean. Previous studies suggest that about 30% of the energy associated with internal tides, especially with high vertical modes, dissipates locally near the generation sites themselves and the remaining 70% of the energy radiates from the source, propagates long distances (O (1000 km)) and ultimately dissipates in deep ocean or in remote continental margins 1-3 . Dissipation of internal tides is one of the important sources of mechanical energy for the vertical mixing in the interior ocean 4 . Several mechanisms have been suggested for the dissipation of long-range propagating internal tides such as interactions with rough topography 5 , interactions with mean flows and eddies 6 , cascade to smaller scales via wave-wave interactions 7 etc. However, the pathways of internal tide energy in the ocean and regions of their energy dissipation are not completely understood.Generally, strong baroclinic currents and large isopycnal displacements at tidal frequencies are observed near their generation sites and their amplitude decreases away from the sources 8,9 . However, spatial variation of internal tides and associated energy dissipation in the ocean can be more complicated due to the interaction of waves from multiple sources 10 . For example, Wang et al. 11 reported that interference of internal tides from different sources results in large spatial inhomogeneity in the energy flu...

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Characteristics of Tides in the Bay of Bengal

Cited by 68 publications

References 16 publications

Tide-rainfall flood quotient: an incisive measure of comprehending a region’s response to storm-tide and pluvial flooding

Tide-rainfall flood quotient: an incisive measure of comprehending a region’s response to storm-tide and pluvial flooding

Mapping the nonstationary internal tide with satellite altimetry

Intensification of tidally generated internal waves in the north-central Bay of Bengal

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