Marine Ecosystems Research Department - jamstec japan agency ...

JAMSTEC 2002 Annual Report
Frontier Observational Research System for Global Change
Quality control of Argo float data is one of most
important missions of our group. We have used the
method developed by PMEL/NOAA as the standard
delayed-mode quality control procedure for Argo
salinity data. Examining and evaluating this method
along with a lot of test calculations, we came to the
conclusion that we should use more sophisticated climatological
dataset to obtain better results on applying
PMEL's method. We are now performing additional
tests to obtain higher-quality float data, and preparing
a new sophisticated dataset of the Pacific Ocean in
cooperation with PMEL.
Using Argo float data and other hydrographic data,
we have been studying the role of mesoscale eddies on
the formation and transport of the North Pacific
Subtropical Mode Water and the characteristics of the
North Pacific Central Mode Water in relation to the
frontal structure.
For the effective use of sparsely distributed Argo
data, we have been developing a D-VAR data assimilation
system on the basis of MOM (GFDL) in cooperation
with researchers of FRSGC. We carried out an
identical twin experiment to verify that the developed
assimilation system performs satisfactorily.
We held an Argo symposium in the spring
meeting of the Japan Oceanographic Society and
reported on the current state of Argo and discussed its
future vision.
(III) Japan Coastal Ocean Predictability Experiment
The Kuroshio is one of the major currents in the
world, and plays an important role in the pole-ward
heat transport as a western boundary current of the
North Pacific subtropical gyre. Our goal is to improve
the accuracy of numerical prediction models for global
climate change by observational study on the variation
mechanism of volume transport and path of the
Kuroshio south of central Japan.
It is believed that the northward current in the
southeast of Nansei Islands (Ryukyu Current System)
and the Kuroshio in the East China Sea meet south of
Kyushu, and form the Kuroshio to the south of
Shikoku and Honshu Islands. However, due to the
mesoscale eddies coming frequently from the east of
the Kuroshio Extension region, there are still several
open questions on the Ryukyu Current System. For
examining its mean state and seasonal variation, and
elucidating the effects of mesoscale eddies and bottom
topography on its driving and variation mechanism,
we have been conducting intensive surveys in the
southeast of Okinawa Island since . We succeeded
in estimating for the first time the mean volume
transport of the Ryukyu Current System in the southeast
of Okinawa Island to be . Sv ( Sv = m /s)
from November to August . This result was
published in the international journal "Geophysical
Research Letters" in January (Zhu et al., ).
In June , PIES (Pressure gauge equipped
Inverted Echo Sounder) were deployed in the southeastern
shelf slopes of Okinawa and Amami-Oshima
Islands from the R/V Mirai in co-operation with
OORD of JAMSTEC, and recovered in December by
the S/V Yokosuka together with the current meters
deployed in November by the T/V Keitenmaru of
Kagoshima University. During the Yokosuka cruise,
we also deployed PIES in the southeastern shelf
slope of Amami-Oshima Island; PIES, ADCP
(Acoustic Doppler Current Profiler) and two DACM
(-Dimensional Acoustic Current Meter) in the southeastern
shelf slope of Okinawa Island; and PIES and
RCM (Recording Current Meter) in the southeastern
shelf slope of Miyakojima Island collaborating with
OORD/JAMSTEC and Kagoshima University, as well
as CPIES (current meter equipped PIES) and PIES
in the East China Sea Kuroshio region collaborating
with the University of Rhode Island (Fig. ).
In addition to the hydrographic surveys, CTD
(Conductivity, Temperature and Depth Meter)
with LADCP (Lowered ADCP), XBT (eXpendable
BathyThermograph) or XCTD (eXpendable CTD)
observations were conducted in June (R/V Mirai),
September (T/S Kakuyomaru of the Nagasaki
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