Identification of thermal front dynamics in the northern Malacca Strait using ROMS 3D-model

The thermal front in the oceanic system is believed to have a significant effect on biological activity.During an era of climate change,changes in heat regulation between the atmosphere and oceanic interior can alter the characteristics of this important feature.Using the simulation results of the 3D Regional Ocean Modelling System(ROMS),we identified the location of thermal fronts and determined their dynamic variability in the area between the southern Andaman Sea and northern Malacca Strait.The Single Image Edge Detection(SIED)algorithm was used to detect the thermal front from model-derived temperature.Results show that a thermal front occurred every year from 2002 to 2012 with the temperature gradient at the location of the front was 0.3°C/km.Compared to the years affected by El Ni?o and negative Indian Ocean Dipole(IOD),the normal years(e.g.,May 2003)show the presence of the thermal front at every selected depth(10,25,50,and 75 m),whereas El Ni?o and negative IOD during 2010 show the presence of the thermal front only at depth of 75 m due to greater warming,leading to the thermocline deepening and enhanced stratification.During May 2003,the thermal front was separated by cooler SST in the southern Andaman Sea and warmer SST in the northern Malacca Strait.The higher SST in the northern Malacca Strait was believed due to the besieged Malacca Strait,which trapped the heat and make it difficult to release while higher chlorophyll a in Malacca Strait is due to the freshwater conduit from nearby rivers(Klang,Langat,Perak,and Selangor).Furthermore,compared to the southern Andaman Sea,the chlorophyll a in the northern Malacca Strait is easier to reach the surface area due to the shallower thermocline,which allows nutrients in the area to reach the surface faster.

Hydrodynamic Modelling of Bidong Island Vicinity Waters

This paper explores the dynamic of meteorological forcing on current circulation pattern in the vicinity of Bidong using an unstructured flexible mesh hydrodynamic model. The forcings were wind, tides, temperature and salinity. The seasonal wind monsoon, mixed tides with dominant diurnal and tropical monsoon climate is characteristics of Bidong Island. We find that this area has different current circulation patterns in response to monsoon changes. It also experienced a small scale of island wake during NE monsoon. This island wake was generated by a strong northeasterly wind. We performed a series of numerical simulations based on three dominant factors in circulation, and evaluated the model using wind, tides and density. We investigated the wind-driven circulation and residual current. This study contributes to the debates on hydrodynamic of current circulation in vicinity of Bidong Island. Specifically, this study was conducted to understand the changes of currents by seasonal wind (NE monsoon and SW monsoon), temperature and salinity.

Coastal oceanographic processes associated with blood cockle (Anadara granosa) induce spawning season in Kapar, Selangor, Malaysia

Study on coastal processes in Kapar waters was conducted from 2008-2016.The aim of this study is to identify potential blood cockle(Anadara granosa)induce spawning ground based on physical intermittency.A total of 132 sampling stations were recorded.A thermal power station situated 2 km away is discharging treated warm water(<40℃)on to the open sea causing the Sea Surface Temperature at near-by cockle culture to intermittent between 31-34℃ while the temperature at the bottom(at 6-8 m Mean Sea Level,MSL)is constant between 29.5℃ and 30.5℃.The results suggested that Kapar waters have two seasons of low waters annually(January-March and June-September,respectively)and the Lowest Astronomical Tide(LAT)occur in late January-February while Great Diurnal Tide is observed on the same period.The bathymetry suggested the present of deep water(6-8 m,MSL)towards the end of cockle culture lot which is closed to merchant shipping lane near Port Klang.Based on water elevation,an area of 255.4 ha within cockle culture lots were identified to have this bottom temperature intermittency(29.5-34.0℃)during its GT and it associated with cockle induce spawning condition.But this area was left out for cockle culture due to its typical depth(>3 m MSL)which prevents cockle farmers from harvesting due to their maximum of 3 m long hand dredge.Thus,this information could be useful for cockle sustainable management plan in near future.