Author(s): Serene Hui Xin Tay; Alamsyah Kurniawan; Seng Keat Ooi; Vladan Babovic
Keywords: Tidal modelling; Grid schematization; Model calibration; South China Sea; South East Asi
Abstract: The South China Sea (SCS) is the largest marginal sea in the western Pacific, and together with the surrounding Southeast Asian seas, located in between the Indian Ocean and the Pacific Ocean, this region has a complex tidal dynamics which is further complicated by the highly varying bathymetry. Most numerical models which focus on the SCS have the extent of their model domain halt at the Sulu Sea in the south east and the southern tip of the Malaysian Peninsular in the south, where the waters of the Southeast Asian seas including the Malacca Strait are simply not modelled. The present study introduces a new SCS model (called the South China Sea Model Curvilinear (SCSMC) ) with a spatially varying curvilinear grid which covers the South China Sea and the surrounding Southeast Asian seas (an area ranging from 95o – 126o E. L. to 8o S. L. – 24o N. L. ) and where the oddly orientated channels or semi-enclosed seas are elegantly schematized to allow smooth flow transition through these areas. This is compared using the same computational code to an existing SCS model (Gerritsen et al., 2003) which is schematized using a spatially uniform rectangular grid of 0. 25 degree resolution that covers the same region. The results show that the curvilinear grid schematization alone has already improved the tidal representation in the Sulu Sea by 17 percent, and an overall improvement of about 6 percent. Further calibration of the open boundary conditions, bathymetry and roughness, results in an overall model improvement of 41 percent, with 75 percent improvement in the Sulu Sea. The SCSMC is also compared to another well-calibrated localized model i. e. Singapore Regional Model (Kurniawan et al., 2011) with regards to the throughflow in the Singapore and Malacca straits where the tides from the two oceans are effectively mixed.