Fast modelling of tidal phenomenon for the Straits of Malacca using laplace spatial interpolation technique
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Date
2014
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Volume Title
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Universiti Teknologi Malaysia
Abstract
Tidal observations are commonly used for tide modelling to increase the reliability of the results of tide prediction. Most of the existing tidal computation techniques such as fourth order biharmonic and discrete tidal zoning technique are include several parameters like tidal constituents, datum and residual. Over 400 tidal constituents have being identified are being used in tidal computational and it makes the computation process are extensive and more tedious. In addition, it is not suitable for onboard and real-time application to have continuous results. Therefore, this study was conducted to develop an application that can provide accurate near-realtime tidal correction for bathymetric reduction based on the observed tides on tide gauge. Spatial interpolation technique is used to find the numerical solution of Laplace’s Equation for tidal field. First, the appropriate boundary condition coefficients were tested and determined by using simulated test basins. For the real test, data from ten tidal stations were selected as the known stations and another ten stations were selected as the check stations such that to cover both sides of the Straits of Malacca. Best solution was obtained with the boundary condition factor a = 0.9 at coastline and the optimum convergence was achieved with the relaxation coefficient r =1.62. The computation of spatial interpolation was developed using Matlab software to provide fast, accurate and continuous tidal corrections for onboard bathymetric reduction which is termed as Direct Tidal Observation Spatial Interpolation Technique (DTOSIT). The computed tides were compared to the value of tidal observation at shore tidal station and also value of sea surface height from satellite altimetry at offshore. In addition to that, a new concept termed as Ceaseless Co-tidal Charts (CCTC) was also developed by adopting the tidal zoning and conventional co-tidal charts. This has minimized the discontinuity of the tidal values in crossing the zones. The statistical results showed correlation of 0.9 between the observed and the modelled tidal values. DTOSIT tidal modelling results slightly higher correlation than the predicted CCTC tides as it used the observed tide in the modelling. The standard deviations of the computed datum levels were around 0.1m and satisfied the International Hydrographic Organization’s standards for the datum requirement
Description
Thesis (Ph.D (Hydrography))
Keywords
Tidal currents