About PORL

Oceanography also called oceanology or marine science is the study of the Earth's oceans and seas. Oceanographers study a diverse range of topics such as plate tectonics to ocean currents to marine organisms. Oceanography is divided into four major areas of research: physical, chemical, biological and geological. The physical aspect of oceanography includes study of physical processes of the oceans such as the currents, tides, development and maintenance of boundary layers, rates of water transport, mixing and turbulence etc. Chemical oceanographers study the chemical constituents of the sea, and the availability of chemical elements in the water. Biological oceanography involves the study of all aspects of life in the sea. Geological oceanographers are concerned with the geological structure and mineral content of the seafloor.

In the past decades great interest to understand circulation of the world oceans, especially the deep ocean, has given impetus to much of our activities today. Oceanography research activities currently undertaken in PORL include climate change, ocean circulation, pollution and other environmental issues on global scales. Oceanic circulation has to deals with a turbulent system with extremely broad spatial scales (from millimeters to 10,000 km) and temporal scales (from seconds to millennia). A complete description of a turbulent system may require knowledge of its ensemble average.

Ship-board measurements have been the primary vehicle for data collection in oceanography our field. However, Such measurements are, however, too slow and costly and they cannot to yield provide complete synoptic pictures of the turbulent oceans on the global scale. Space engineering has in the past decade or so given a new alternative provided new ways of observing the oceans. Satellite observations not only provide global coverage of for synoptic circulation in the oceans, they are also more cost effective than traditional ship-board measurements. However, satellite observations are limited to the surface state because sea water is conductive and radiative waves cannot penetrate the oceans. Thus, the global observation network should combine observations from satellite measurements with and automatic instruments that conduct subsurface in-situ measurements.

The Physical Oceanography Research Laboratory (PORL) was set up in June 1995 by the National University of Singapore (NUS) as a part of Tropical Marine Science Institute (TMSI). PORL is constantly working on research and development of diverse issues related to in the fields of ocean and coastal modelling. This includes modelling of surface wave generated by wind; simulation of currents, driven by wind, wave and tidal forcing; modelling of catchments runoff, sea water turned to fresh water reservoir, tidal barrage, surface water discharge to the sea; a suite of water quality models for acute and chronic chemical spills; sediment transport model. All the models are three-dimensional, state-of-the-art in their respective fields. Whenever appropriate either physically based numerical models and/or data driven models are considered or complementing each other.

For wind generated waves two basic models are used: WAM – for the larger domains, such as South-China Sea and Malacca Straits; and SWAN - for the smaller domains. The circulation models are based on the Princeton Ocean Model (POM). Several fundamental modifications have been made in POM to take into account other important phenomena, e.g. wave-current interaction and mixing due to breaking waves. Both, WAM and POM have been coupled in a single code to simulate influence of waves on current circulation with feedback. The models are equipped with the customized data assimilation algorithms, which significantly improve accuracy of forecast with the use of previously recorded data.

The in-house developed water quality model suit is capable of simulation of eutrophication, oil spills, radionuclide and chemical spills. The models utilize recent achievements in computational science and chemical kinetics. To take into account the influence of bed morphology on currents and maritime activities, the custom-made sediment transport model is coupled with the circulation model.

Data driven techniques have been increasingly considered to complement the various activities. Data assimilation technique has been coupled with ocean models to further enhance their prediction performance.

All the models are rigorously tested and validated for South China Sea, Singapore and Malacca Straits. They are used routinely for forecasting purposes.

Our domains of research interest.