Abstract

This work utilized temperature-salinity (T-S) diagram to explore the physical properties of water masses during intermonsoon period. In doing so, the physical properties of water column, such as temperature and salinity are collected from cruise conducted in September 2002 and October 2003. Hydrolab instrument was used in the coastal water of Kuala Terengganu, Malaysia. The vertical water temperature and salinity with 5 m water depth intervals have been collected from over 24 sample stations using Hydrolab. The T-S diagram has been modelled using Python interface to NCAR Command Language (NCL)’s graphics library (PyNGL). The core method of T-S diagram has been used to find out the water mass physical properties. This study shows that in September 2002, the core of water mass is characterised by water density of 20.8 kg/m³, salinity of 33.3 psu and temperature of 29.3°C. However, in October 2003, the core of water mass is difficult to identify because of well mixing event. Furthermore, the ratio of between September and October is about 4.7. In conclusion, T-S diagram can be used to find out the water mass types and estimate the length of mixing during intermonsoon period. The water mixing is the main feature of coastal water body of Kuala Terengganu because of its shallow depth.

Key words: South China sea, water masses, intermonsoon period, temperature-salinity (T-S) diagram, salinity, temperature.