Abstract:
Effects of tide and wind on simulated current in the Gulf of Thailand were studied using RMA2 v.4.5 (Resource Management Associates) in SMS7.0 (Surface Modeling System). RMA2 is a two dimensional depth averaged finite element hydrodynamic numerical model. Important inputs used in the model were wind velocity from Navy Operational Global Atmospheric Prediction System (NOGAPS), observed sea level, river in flow and water depth from navigational charts. It was found that the current patterns in inter-monsoon period from northeast to southwest and southwest monsoon season were similar, current entered the Gulf of Thailand along the western part of the Gulf, curved to the east, then flowed parallel to the peninsular and left at the southern open boundary. In Inter-¬monsoon period from southwest to northeast and northeast monsoon season, current entered the Gulf along the eastern part of the Gulf, curved to the western part of the Gulf and flowed out along the eastern part of open boundary. When river inflow was introdnced into the model, it was found that river inflow affected the circulation pattern only around river mouths in the Upper Gulf of Thailand especially during southwest monsoon. From all observations, tide significantly affected the circulation pattern in the Upper Gulf of Thailand. Effects of wind magnitude and direction on wind, bottom topography and coastline effected current pattern and eddies in the Gulf of Thailand. Effects of tide on current were studied by forcing the model with four major harmonic constituents which are M₂, S₂, O₁, and K₁. Sea levels were rising from the western part of the Gulf to the eastern part when forcing by M₂ and S₂. While sea levels were rising from the eastern part to the western part when forcing by O₁ and K₁.