3rd ASEAN Science & Technology Week
Regional Ocean Dynamics Conference
"Modelling techniques- An Effective Tool to Understanding the influence of Sea Level in the ASEAN region" was the theme of a meeting held in Singapore with 14 papers presented by scientists from Australia, Canada, Malaysia, Indonesia, the Philippines, Singapore, and Thailand. The focus was on tides in this area, where the Western Pacific and Indian Ocean connect through a complex weir of straits and islands. The vast majority of models used the finite difference technique and were almost uniformily designed for practical purposes such as oil spill tracting etc. The papers were presented in the context and as a progress report of the on-going ASEAN Regional Ocean Dynamics project started in 1989. It is the continuation of the initial Tides and Tidal Phenomena project started in 1985. This is a long-term multi-national effort to understand the oceanography of the region augmented by a linked system of high quality tidal stations and moored and bottom arrays of oceanographic measuring devices.
by Pat Wilde
The third Science and Technology Week conference and exhibition was held in Singapore from 21 to 24 September 1992. This meeting of ASEAN (Association of South East Asian Nations: Brunei, Indonesia, Malaysia, Philippines, Singapore and Thailand) occurs once every three years and is held in conjunction with a meeting of the Science and Technology Ministers from the ASEAN countries. The two previous conferences were in Malaysia and in the Philippines. The theme for the 1992 meeting was "Socio-Economic Growth in ASEAN through Science and Technology". The meeting was sponsored by ASEAN COST (Council On Science and Technology). This meeting has special significance to Singapore as September is annually Technology Month, emphasizing the importance of Technology to the Singapore economy. Several simultaneous conferences were held during the week including: (1) Biotechnology: 10 sessions; (2) Food Science and Technology: 10 sessions; (3) Non-conventional Energy: 10 sessions; (4) Marine Science: Living Coastal Resources: 14 sessions; (5) Marine Science: Regional Ocean Dynamics: 5 sessions; (6) Microelectronics and Computers: 11 sessions; (7) Material Science and Technology: 9 sessions; (8) Science and Technology Policy: 2 sessions. The two Marine Science Conferences were further divided into theme technical sessions. For Living Coastal Resources, the sessions were Remote Sensing Applications; Colonisation and Recruitment of Artificial Substrate; Reef Benthos Studies; Mangrove Community Function, Seagrass Community Structure and Biology; Seagrass-Associated Fauna; Fish Habitats and Biology; Plankton and Nutrient Dynamics; Soft Bottom Communities; and Management and Conservation. For Regional Ocean Dynamics, the sessions were Tidal Measurements; Modelling Technique; and Modelling Techniques in the ASEAN region. I attended the Regional Ocean Dynamics Conference and will report in more detail as follows.
REGIONAL OCEAN DYNAMICS CONFERENCE SESSIONS
This conference is basically the report of the ASEAN-Australia project on "Tides and Tidal Phenomena" phase II, which is the "Regional Ocean Dynamics project. Phase I was "Tides and Tidal Phenomenon Project" which initiated the first "simultaneous and comprehensive measurement" of tides in the ASEAN area. The theme of the session was "Modelling Techniques - An Effective tool to Understanding the Influence of Sea Level in the ASEAN Region." As mentioned above, the conference was divided into three sessions.
The initial session, chaired by Dr. George Cresswell of CSIRO Hobart, Tasmania had three papers. The lead-of paper was by Prof. G. W. Lennon of Flinders University of South Australia on "The ASEAN Seas and their links with Climate." The discussion was a summary of activities of the Physical Marine Sciences projects under the auspices of the ASEAN/Australia Economic Cooperation Program (AAECP) which began in 1985. The initial program on Tides and Tidal Phenomena had the goal of building a sea level data bank for the region and had to deal with the practical issues of operating and maintaining tidal stations as well as training personnel. Realizing the importance of the this region to the general understanding of oceanographic processes as the area essentially is a weir between the Pacific and Indian Oceans, the follow-on program "Regional Ocean Dynamics" was begun as a second phase in 1989. The inter-ocean transport is estimated to be in the range of 2 to 18 Sverdrups (one Sverdrup = one million cubic meters per second) with water from the Central West Pacific warm pool moving into the Indian ocean. Thus the characteristics of the "Indonesian Throughflow" would have implications for Global climatic processes may be involved in triggering the aperiodic El Nino/Southern Oscillation (ENSO) climatic event, which has large scale economic effects on fisheries by modification of upwelling and nutrient transport and agriculture by inducing drought cycles.
Phase I results were the establishment of an array of tide gauges each with two different sensors and three recording systems. The data are transmitted to the National Tidal Facility in Adelaide and placed into a "formal Data Bank of Sea Level and Tides" for the ASEAN community. Quality control was achieved by comparing the results from the two gauges from the Thailand station Ko Nu and at the Raffles Lighthouse in Singapore. After allowance for calibration problems and other retrievable corrections, the records vary only to a few centimeters.
Phase II built on Phase I experience and extended the goals of Phase I to an understanding of the current flow and take a three-dimensional approach which would include current meters, XBT (eXpendable BathyThermographs), and CTD Conductivity/Temperature/Depth) casts as well as installation of 24 new tidal stations. The targeted areas are the Equatorial Straits, the South China Sea, Makassar Straits, Maluku Straits and through the Halmahera Sea. In shallow water moorings a bottom-mounted Acoustic Doppler Current Profiler will be used. For deep water, conventional taut-wire moorings will be used. This cruise is scheduled to take place from May 1993 to April 1994 using Indonesian, Malaysian, and Singaporian research ships.
Prof. Lemmon also discussed the preliminary observation that there is an inverse correlation between sea level between the South Coast of Australia and California. Also that a rise in South Australia is a precursor a year in advance to an El Nino in the Eastern Tropical Pacific.
Captain Hassan of the Royal Malaysian Navy gave the second talk on "Tidal Services by the Hydrographic Department-Royal Malaysan Navy." He discussed the history of hydrographic department and its role in co-operating with the ASEAN tidal and regional dynamics projects. Five high quality tide gauge stations will be maintained across the breath of Malaysia for these programs as well as integration of the 21 existing tide gauge stations with the ASEAN Data Base.
Mr. Efren P. Carandang of the National Mapping and Resources Authority, Coast and Geodetic Survey Department of the Philippines discussed, in the third paper of this session, on "Preliminary Study on Sea Level Variations in the Philippine Islands." For the ASEAN tidal projects five combination digital/analog primary tide gauge stations were installed with 50 secondary stations. The primary stations are to be run continuously whereas the secondary stations will be observed from periods of from 15 days to several months. Observations thus far show high correlations with the direction of the Monsoon. In the Summer SouthWest Monsoon sea levels are higher accompanied with floods and storms (Typhoons). In the Winter Northeast Monsoon sea level is up to 10 centimeters lower. Long term records from Manila Bay suggest rising Mean Sea Level of 0.3 meters starting in 1965 through 1990. Possible causes such as subsidence, increased river discharge due to deforestation have been suggested but no conclusive explanation has been found. A lowering of 0.005 meters Mean Sea Level has been noted at Jolo, an island at the southwest end of the Philippines off the coast of Borneo.
The second portion of the Tidal Measurements Session by chaired by Kasijan Romimohtato. Captain Vichai Panpruk of the Oceanographic Division, Hydrographic Department of the Royal Thai Navy talked on "Sea Level in Thailand." Since 1940, 23 permanent tide gauge stations have been operational in Thailand. This was increased by 5 high quality special tide gauge stations for the ASEAN network as discussed previously. Sea level in Thai waters is influenced by the Monsoons with lowering of MSL in the Southwest Monsoon (Feb.-June) and rising in the Northeast Monsoon (Aug.-Jan.) for the Gulf of Thailand on the South China (Pacific) side. On the Andaman Sea (Indian Ocean) side, MSL increases with the Southwest Monsoon and decreases with the Northeast Monsoon. Long term trends are not obvious. Only in the upper Gulf of Thailand has MSL risen about 10 mm, which may be attributed to subsidence and reduction of river outflow due to dam construction.
The final paper of this session was by Dr. Donald O. Hodgins of Seaconsult Marine Research Ltd. of Vancouver, British Columbia, Canada. This was a descriptive talk about the use of the proprietary High-Frequency Radar system based on experience in British Columbia. The system is highly portable and runs from gasoline powered generators. The basic physics are discussed and application for use in a wilderness area in Queen Charlotte Sound in Canada are described. The system has a center frequency of 12.5 MHz with a spatial resolution of 0.00391 Hz, which translates to a Doppler velocity resolution of about 3.3 centimeters per second for a one hour average current radial vector sum every 5 degrees. The range is 60 kilometers and a coverage of 2000 square kilometers. Comparision with drifters was made and a "close correspondence" was seen allowing for Loran C error on the drifters. This paper was given to demonstrate potential new techniques of current measurements particularly suitable for the portable field measurements in the numerous straits and passages between islands in the ASEAN region.
This technical session was chaired by Dr. Hassan of Malaysia and Renato Feir and contained five papers. Prof. N. Jothi Shankar, for his colleagues Cheong Hin-Fatt and Chan Chun Tat of the Department of Civil Engineering, National University of Singapore and Toh Ah Cheong of the Port Authority of Singapore, presented a paper entitled "On Some Experiences in the Numerical Modelling of Shallow Water Wave Equations." This paper discusses a case study of the nested tidal model using system 2DTIDFLO for the waters near Singapore. The regional coarse scale model has a mesh size of 1 X 1 kilometers. The central detail model covering an area of about 30 X 30 kilometers, uses a grid spacing of 250 X 250 meters. Guidelines used are: 1. boundaries of the model should be chosen so the mainflows are nearly perpendicular to the boundary; 2. a zone of adjustment is usually needed to provide a smooth transition from the coarse regional bathymetry to the finer detailed bathymetry of the nested model; 3. velocity boundary layer conditions may be preferred to water level boundary conditions; 4. for small grids, the model bottom friction may not be able to dissipate "unwanted" wave components, in such cases either Verboom's or Stelling's techniques could be used. Sandra Hodgins gave J. A. Stonach's paper on "Applications of Three-Dimensional Hydrodynamic models" Both are from Seaconsult Marine Research Ltd. of Vancouver, British Columbia, Canada. This is the second paper giving a Canadian example from the British Columbian area. The numerical model discussed calculates currents, provides advection for salinity and "inert" i.e. non diffusive scalars such as sediment, certain pollutants or plankton. Examples are given for modelling sedimentation rate, three-dimensional dispersion of pollutants from an outfall, velocity fields for tracking an oil spill, and a total ecosystem for predicting availability of food for juvenile salmon. Back to the ASEAN area, with a paper by J. T. Lim and N. H. Yeong of the Malaysan Meteorological Service on "A Method of Estimating Coastal Winds in the Equatorial Region." This model described here for the coast of Sarawak uses the assumption that in equatorial regions where synoptic winds are weak, the coastal winds are cyclic reversals of land/sea breezes. The model is a two dimensional modification of Haurwitz, where the driving force for the wind is the difference between the air temperature over the land and the sea. The inland extent of the wind is also modelled, which can be up to 20 to 50 kilometers from the shore. The final Canadian paper by Dr. M. G. G. Foreman of the Institute of Ocean Sciences, Department of Fisheries and Oceans of British Columbia explores the potential of finite element methods for modelling the situation in complicated coastal geometries such as in the ASEAN waters. Dr. Foreman outlined the previous problems with the method and how most of the difficulties have been solved. The last major barrier, which is the more complicated mathematics compared to finite difference models is essentially alleviated by the availability of cheaper and faster computer systems. Again the examples are from the Pacific coast of British Columbia. The automatic gridding system TRIGRID is available for users with UNIX based workstations or with DOS-Fortran. The model described uses a Galerkin finite element method with "the governing equations two or three dimensional shallow water equations with the continuity equation replaced by a second-order wave equation." Examples of model runs for the coastal areas in British Columbia include: tidal M2 co-amplitudes, co-phase and resonance; buoyancy currents at given depths; and tidal currents. Prof. Abdul Aziz Ibrahim, Director of the Coastal and Offshore Engineering Institute and his colleague Dr. Ahmad Khairi Abdul Wahab, both of the Universiti Teknologi Malaysia gave a paper "Water Circulation Modelling" which was a description of the finite difference model applied to coastal situations. The Malaysian program is in Fortran and is run on a 386 DOS machine.
Use of Modelling Techniques in the ASEAN Region
The initial talks in this session on models for the Straits of Malacca were chaired by Wilson Chua of the Port Authority of Singapore. Ivonne M. Radjawane, as the speaker, and her colleague Dadang K. Mihardja both of the Bandung Institute of Technology of Indonesia presented a model "On Tidal Dynamics in the Malacca Strait." She described the results from a finite difference model of the M2, S2, K1, and O1 components of the tides. Grid size is 10 minutes (1833 meters) in the East-West direction and 3 1/3 minutes (6111) in the North-South direction. The total area covered is 69 by 82 grid cells. The dominant tide in the strait is semidiurnal, with a part of the southern portion with a mixed semidiurnal dominant tide. The natural period is 12.52 hours (M2 = 12.41). The major influence is from the west from the Andaman Sea and the Northern Indian Ocean. The model was verified with existing data during a 14 day computer simulation. Dr. Safwan Hadi of the Institut Teknologi Bandung, Indonesia complemented the previous discussion of the tidal model with a talk on the "Hydrodynamics Model of the Malacca Strait." This also is a finite difference model developed to look at the current patterns in the Straits. It confirmed the influence of the western side of the Straits, but also noted no effect of Monsoonal wind shifts on currents.
The final talks were chaired by Sommai Poomipol. Toh Ah Cheong of the Port of Singapore Authority presented their approach on "Computer Modelling of Oil Spilled in the Sea." The model used is a tidal hydrodynamic model specifically designed for the area around Singapore. For the Straits of Singapore the tidal cycle is 25 hours with 16 hours flowing from the West (Andaman Sea-Straits of Malacca) and 9 hours from the East. Because of the imbalance in time caused by the dominance of the Indian Ocean tides, the westerly flow is at lower velocities than the compensating easterly flow. This model is used directly for practical purposes for real-time oil spills and prediction of drift of abandoned ships taken over by pirates which still infest the Straits. Because of the real-time nature of potential pollution problems, the model is not run in real-time. Instead a series of likely pre-run scenarios are used at the initial phase of an oil spill based on the location and occurrence in the tidal cycle to initial protection and clean-up procedures. The most critical variable is wind, with respect to oil spill drift, as the tidal currents are reasonably predictable. The model is used not only for prediction of drift of oil spills but also for hincasting of the origin of illegal oil spills. The final paper given was by Dr. Dadang Kurniadi Mihardja of the Institut Teknologi, Bandung, Indonesia on "Tidal Energy Dissipation on the Southeast Asian Waters." This was a model comparison of the M2 tidal energy dissipation for ASEAN waters with previous published values. Seven "passages" were examined: 1. Northwest Australia to the lesser Sunda Straits; 2. Formosa Straits to Luzon; 3. Sunda Straits; 4. Malacca Straits; 5. Mindanao to West Irian; 6. Torres Straits; and 7. Philippines. The total energy dissipation by bottom friction is 107.3 thousand megawatts, by turbulence 106.4 thousand megawatts. The total energy dissipation is thus 213.7 thousand megawatts with the energy flux for the region is 214.1 thousand megawatts.
This first meeting of the Regional Ocean Dynamics project of the ASEAN-Australia program demonstrates the real value of regional co-operation in Science. The pooling of talent and resources of this group of nations with a vast variation in economic strength, education, languages, religions, political systems and stage of development essentially linked only by common geography and oceanography is a miracle to me. Despite all the differences, I certainly got the feeling of genuine co-operation and a spirit of scientific comradeship and bootstrapping to bring tidal and in general oceanographic measurements and analyses to a high international standard. The presence of a strong Canadian presence was countered by a lack of American presence except for me as an Observer and certainly not as an active participant. In fact, as far as I knew I was the only American at the whole conference. There certainly were no American exhibitors (there were two Russian booths) and I saw no Americans at the various social functions. In fact, I may have had to suffer a grievous insult as one lady came up to me and asked: "Are you from Australia?"! The lack of a US presence was sad as even the Canadians mentioned that most of the advances in modelling, especially for the finite element techniques was going on in the US. As this was a primarily a tidal meeting, there were academic ties to the US through Prof. Klaus Wyrtki of the University of Hawaii, who has actively worked in the region, particularly in Indonesia. Some of the ASEAN scientists were trained as graduate students by Prof. Wyrtki. However, after talking with some of the younger scientists, it was clear they would now would do graduate or post-graduate work in Europe or Australia. Part of this is a residual of the British Commonwealth status for Singapore and Malaysia, while the rest is the recognition that in many areas, such as tides, Europe is now in the forefront of science.
One thing is certain, the ASEAN nations, led by Singapore, are united in the goal of economic development and are actively and vigorously supporting advances in both science and technology.