3rd ASEAN Science &
Technology Week
September 1992
"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
by Pat
Wilde
INTRODUCTION
The third Science and
Technology Week conference and exhibition was held in
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.
Tidal Measurements
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
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
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
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
Mr. Efren P. Carandang
of the National Mapping and Resources Authority, Coast and Geodetic Survey
Department of the
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
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.
Modelling Techniques
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.
DISCUSSION
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.