Seasonal Variation of Stratification in the Gulf of Thailand

Intensive hydrographic observations were carried out in the western part of the Gulf of Thailand and the east coastal sea of Peninsular Malaysia in September 1995 and April–May 1996. The characteristics of seasonal variation of oceanic condition in that area are discussed basis of an analysis of observed water temperature, salinity and density distributions in these cruises and NAGA cruises (Yanagi and Takao, 1998a). Stratification is most developed in March–May mainly due to large sea surface heating and weak sea surface wind, which weakened until September–October, vanishing in December–January. The horizontal distribution of bottom cold, saline and heavy water masses, which are found during the stratified season, is governed by the tidal mixing and the water depth. Water exchange between the Gulf of Thailand and the South China Sea becomes large in March–May due to a coupled effect of the intensified estuarine circulation and the Ekman transport by the southwest monsoon. This revised version was published online in August 2006 with corrections to the Cover Date.