SOME CALCULATED RESULTS OF CURRENT IN THE GULF OF TONKIN BY USING NONLINEAR THREE DIMENSIONAL (3D) MODEL
Keywords:Tide, current, three-dimensional (3D) nonlinear model, finite element method (FEM), Gulf of Tonkin.
AbstractAmong marine investigation and study activities, the studies and calculation of dynamic system are very necessary and important, especially in the Gulf of Tonkin (Vietnam), where many economic and social activities are happening and where is affected not only by the fresh water from Red river but also by the western currents in the South China Sea through the gulf mouth and Quynh Chau Strait (between Leizhou Peninsula and Hainan Island). Up to now, the results of study, calculation and simulation of the currents in the Gulf of Tonkin with consideration on these factors and climate change effects leading to the change of occurring time, wind intensity, wind season length are very different compared to the previous results and they are still very limited and unsystematic. In this paper we tried to solve the three-dimensional (3D) nonlinear model of currents during northeast and southwest monsoons in this region using finite element method (FEM). The calculation results showed the main characteristics, the spatial and depth variation of intensity and direction of the current fields during typical monsoons in the Gulf of Tonkin. The calculation results showed that: Quynh Chau Strait plays an important role in water exchange between the Gulf of Tonkin and the South China Sea; The wind currents play an important role inside the Gulf of Tonkin and the density currents (thermo-haline, regular currents) play an important role inside and outside the main mouth of the gulf; Strong regular currents are existing (in the whole year with two wind seasons), flowing from north to south through the gulf mouth (this has been approved by some previous study results) in which the density currents play the main role; Cyclones have been formed in northeast monsoon and anticyclones have been formed in southwest monsoon in the gulf.
Tanabe, S., Hori, K., Saito, Y., Haruyama, S., Sato, Y., and Hiraide, S., 2003. Sedimentary facies and radiocarbon dates of the Nam Dinh-1 core from the Song Hong (Red River) delta, Vietnam. Journal of Asian Earth Sciences, 21(5): 503-513.
Zong, Y., Huang, G., Switzer, A. D., Yu, F., and Yim, W. S., 2009. An evolutionary model for the Holocene formation of the Pearl River delta, China. The Holocene, 19(1): 129-142.
Shaw, P. T., and Chao, S. Y., 1994. Surface circulation in the South China Sea. Deep Sea Research Part I: Oceanographic Research Papers, 41(11): 1663-1683.
Penjan, R., Siriporn, P., Natinee, S., and Somboon, S., 2000. Temperature, salinity, dissolved oxygen and water masses of Vietnam waters. In Proceeding of the SEAFDEC seminar on fishery resources in the South China Sea area IV: Vietnamese water (pp. 346-355). Southeast Asian Fisheries Development Center Thailand.
Qi-zhou, H., Wen-zhi, W., and Jun-chang, C., 1994. Tides, tidal currents and storm surge set-up of South China Sea. In Oceanology of China seas (pp. 113-122). Springer Netherlands.
Manh, D. V., and Yanagi, T., 1998. A three-dimensional numerical model of tide and tidal current in the Gulf of Tongking. Oceanographic Literature Review, 45(1): 22.
Manh, D. V., and Yanagi, T., 2000. A study on residual flow in the Gulf of Tongking. Journal of oceanography, 56(1): 59-68.
Đinh Văn Ưu, 2011. Tiến tới xây dựng hệ thống mô hình dự báo và kiểm soát môi trường Biển Đông. Hội nghị Khoa học và Công nghệ biển toàn quốc lần thứ 5, Quyển 2: Khí tượng Thủy văn và Động lực học biển, tháng 10 - 2011, Hà Nội. Tr. 43-49.
Bùi Hồng Long, Trần Văn Chung, 2007. Một số kết quả tính toán dòng triều bằng mô hình ba chiều (3D) cho vịnh Bắc Bộ. Tạp chí Khoa học và Công nghệ biển, 7(4): 10-26.
Minh, N. N., Patrick, M., Florent, L., Sylvain, O., Gildas, C., Damien, A., and Van Uu, D., 2014. Tidal characteristics of the gulf of Tonkin. Continental Shelf Research, 91, 37-56.
Bùi Hồng Long, Trần Văn Chung, 2007. Tính toán dòng triều tại cụm Song Tử bằng phương pháp phần tử hữu hạn. Tuyển tập Báo cáo Hội nghị Quốc gia “Biển Đông-2007”, ISSN 1859-2430, 735-750.
Bui Hong Long, Tran Van Chung, 2008. Calculations of currents in Northeast Cay and Southwest Cay, South China Sea, using 3D linear model. Proceedings on the Conference on the results of the Philippines-Vietnam joint oceanographic and marine scientific research expedition in the South China Sea (JOMSRE-SCS I to IV), 161-173.
Bui Hong Long, Tran Van Chung, 2009. Calculations of tidal currents in Van Phong bay using the finite element method. Advances in Natural Science, 10(4): 495-478.
Bùi Hồng Long, Trần Văn Chung, 2009. Nghiên cứu chế độ dòng dư tại vùng biển Nam - Trung Bộ Việt Nam. Tạp chí Khoa học và Công nghệ biển, 9(4): 5-24.
Trần Văn Chung, Bùi Hồng Long, 2014. Đặc trưng thủy động lực vực nước Bình Cang - Nha Trang qua mô hình FEM và ECOSMO. Tạp chí Khoa học và Công nghệ biển, 14(4): 320 - 331.
Mellor, G. L., and Yamada, T., 1982. Development of a turbulence closure model for geophysical fluid problems. Reviews of geophysics and space physics, 20(4): 851-875.
Blumberg, A. F., Galperin, B., and O’Connor, D. J., 1992. Modeling vertical structure of open-channel flows. Journal of Hydraulic Engineering, 118(8): 1119-1134.
Gill, A. E., 1982. Atmosphere-ocean dynamics (Vol. 30). Academic press.
Galperin, B., Kantha, L. H., Hassid, S., and Rosati, A., 1988. A quasi-equilibrium turbulent energy model for geophysical flows. Journal of the Atmospheric Sciences, 45(1): 55-62.
Smagorinsky, J., 1963. General circulation experiments with the primitive equations: I. the basic experiment*. Monthly weather review, 91(3): 99-164.
Large, W. G., and Pond, S., 1981. Open ocean momentum flux measurements in moderate to strong winds. Journal of Physical Oceanography, 11(3): 324-336.
Trenberth, K. E., Large, W. G., & Olson, J. G., 1990. The mean annual cycle in global ocean wind stress. Journal of Physical Oceanography, 20(11): 1742-1760.
Lynch, D. R., Ip, J. T., Naimie, C. E., and Werner, F. E., 1996. Comprehensive coastal circulation model with application to the Gulf of Maine. Continental Shelf Research, 16(7): 875-906.
Lynch, D. R., and Naimie, C. E., 1993. The M2 tide and its residual on the outer banks of the Gulf of Maine. Journal of Physical Oceanography, 23(10): 2222-2253.
Fang, G., Kwok, Y. K., Yu, K., and Zhu, Y., 1999. Numerical simulation of principal tidal constituents in the South China Sea, Gulf of Tonkin and Gulf of Thailand. Continental Shelf Research, 19(7): 845-869.