Numerical Study on the Circulation in the Gulf of Thailand and Its Seasonal Water Exchange with the South China Sea

Abstract

      Gulf of Thailand is a semi-closed shallow water basin connected to the South China Sea. The seasonal Circulation patterns in the Gulf of Thailand and its water exchange with the South China Sea are studied using the CROCO model from 2017 to 2020. The simulated temperature, salinity, Sea surface height and current field agree with the observation well.  Based on the model result, the upper flow velocity of the horizontal flow field in the Gulf of Thailand a is greater than the lower flow velocity, which means that the Ekman flow driven by the monsoon dominates the upper flow field. Winter and summer are the strongest periods of the monsoon in the sea area, as well as the strongest periods of water exchange between the Gulf of Thailand and the South China Sea. In winter, the upper layer of South China Sea water flows into the Gulf of Thailand, causing an increase in SSH, causing the middle layer of seawater to sink and flow out from the bottom; In summer, the upper layer of Gulf of Thailand water flows out, SSH decreases, the middle layer of seawater surges up to supplement the surface deficiency, and the bottom layer of South China Sea water flows in to compensate.  Keywords: Gulf of Thailand, Circulation patterns, Gulf of Thailand, South China Sea