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Dr.Jong-Hwan Yoon
Kyushu University Applied Dynamics Research Center
< Major research themes >
| 2002.10 - : |
The deep circulation of the Japan Sea. |
| 2002.10 - : |
The deep circualtion of the Japan Sea. |
| 1997.02 - : |
Development of heavy oil spill behavior forecasting
model |
1996.04 -
2002.03: |
Research on formulation of water mass in the
Japan Sea |
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What about satellite data makes it essential
to understanding what is occurring in the marine environment? |
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My work involves comprehending the ocean cycles
and making forecasts. For this I use data including sea-surface altitude,
water temperature and wind direction. Satellite data is indispensable
to my research as it forms the basis for resetting the initial conditions
for predictive models. On-site measurements are difficult to immediately
reflect in models, while, satellite data offers something closer
to real time. This makes it possible to comprehend the surface current
for a large area using sea-surface altitude data, which is essential
in constructing predictive models.
In addition, satellite surface altitude data is used to check the
results of marine cycle models and under the Argo Project, nearly
3,000 profiling floats have been released into the world's oceans.
Floating on the surface, these regularly monitor the salinity and
vertical profile of the water temperature. This data is gathered
via satellite. |
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Currently, what kind of research are you
carrying out? |
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I am conducting research on the oceanic circulation
of the Pacific Ocean and Japan Sea. In regard to the latter, I am
using satellite data to put together a short-term prediction methodology
for up to five days in the future and a long-term version for up
to two months in the future. In research on the Tsushima Current,
cruise ships that regularly travel through the area are used to monitor
current velocity, surface temperature, salinity and chlorophyll.
In addition, models have been constructed that predict the advection
and diffusion for heavy oil drifts and these have been confirmed
largely accurate via on-site monitoring of actual heavy oil drifts.
Monitoring of the Japan Sea has also been conducted using profiling
floats. |
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What requests do you have or what would you
like to see happen regarding satellite data?? |
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Currently, satellite data is being used for two-month
oceanic circulation forecasts. I am inputting tidal information for
the five-day forecast. The tidal data has a large impact on coastal
areas. Due to conditions having to do with the time resolution the
TPEX/ERS sea-surface altitude is supplied at around an interval of
every 10 or 30 days so it is not possible to incorporate this into
short-term forecasts. If the time resolution of information improves,
then I think we can expect to see it used in short-term forecasts. |
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What research interests you right now? |
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would like to gain an understanding of the effects that global warming
will have on the Sea of Japan. In the Japan Sea, up until about 50
years ago, there was a convection current that flowed deep in the
ocean. However over the past 50 years, this has almost entirely disappeared
and I think that this may be an early impact and indication of global
warming. I would like to investigate this and make a model based
on the structural changes that the past 50 years has brought to the
Japan Sea - known as the Mini Pacific Ocean. This model could then
be used to forecast future changes. Ultimately, we would like to
expect that this will segue into a means of predicting change to
the marine environment on a global scale. The ocean's vertical circulation,
both from a marine life and a thermal circulation perspective, is
very important. When the vertical circulation ceases, this has the
potential to cause drastic changes in climate. The climate is intimately
related to the ocean's vertical circulation and I believe that vertical
circulation data will provide a hint that aids in the forecasting
of climate change.
I am trying to boost the level of accuracy in other circulation models.
As a result, we have become able to reproduce on a small scale, the
structure of the occurrence of the Karman Vortex that takes place
in the wintertime in the western channel of the Tsushima Current.
Also, it is well known that a counter-clockwise current has been
observed in deep in the Japan Sea, and while conventional models
were not able to reproduce this, however by heightening the precision
of the circulation model we were able to recreate this phenomenon.
I believe that satellite data can be used to compare these circulation
patterns that typically appear.
In the future, I would like to target the East Asian seas, putting
together a model fusing the Japan Sea, Yellow Sea and East China
Sea, which, for instance, could be used to show the change in fresh
water currents due to the construction on the Three Gorges Dam. Freshwater
is important biologically and from a physics viewpoint as layers
of the ocean with more freshwater are lighter and likely have an
impact on circulation. |
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What are some issues related to use of satellite
data? |
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When comparing the monitoring results of buoys
and satellite data, I think that it is apparent that the frequency
of data sampling needs to be increased. Also, TOPEX's sea-surface
altitude measurements, due to a low level of accuracy in regard to
the geoid, tend to have large margins of error. Currently, I am using
information about the amount of fluctuation of the sea-surface altitude.
I think that issues regarding the basic principles of this remain
to be resolved. Nonetheless, as it allows for the gathering of information
for a broad area, satellite data is essential for marine monitoring. |
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( Interview date: April 10, 2005 ) |
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