Marine Ecosystems Research Department - jamstec japan agency ...

Japan Marine Science and Technology Center
Ocean Observation and Research Department
fresh water was sometimes observed by the CTD profiler
moored in subtropical regions. It originated from
the subarctic region north of the Kuroshio Extension.
In FY we studied the background flow field when
the water was appearing. Sea surface current calculated
by satellite altimetry showed that there was an anticyclonic
eddy between the CTD site and the Kuroshio
Extension after late June. The southern eastward flow
of the eddy was associated with that of the Kuroshio
Extension. After the flow direction changed westward
shown in the current meter at the site, which is affected
by the eddy, the fresh water appeared early in July
(shown in Fig. ). Therefore it was suggested that the
appearance of the fresh water could be associated both
with the eddy and the inflow from the Kuroshio
Extension region.
() Monitoring of the Kuroshio and the Subtropical
Gyre
A monitoring study was made in order to evaluate
the ocean surface heat transport of the Kuroshio and
the subtropical flow. The observation was carried out
in collaborated with Tohoku University. The Kuroshio
was monitored by shipboard ADCP mounted on the
ferry Ogasawara-Maru shuttling between Tokyo and
Chichijima. Temperature sections were made
bimonthly by XBTs along the ferry track. Moreover,
we made preparations for another ADCP monitoring
by a ship that would make three round trip between
Japan and Hawaii across the western side of the subtropical
gyre in north Pacific.
Theme 3: Arctic Ocean Research
The amplitude of climate variability in the Arctic
area is the largest in the Earth climate system. For
example, the retreat of summer sea ice showed a
record value in the Arctic Ocean in (Fig. ).
Especially, the retreats in the area adjacent to the
Pacific Ocean and the Atlantic Ocean are quite
remarkable. Such a marginal region of the Arctic sea
ice would be easily affected by ice-albedo feedback.
The regional variability bears good evidence that the
Salinity: pressure gridded data
pressure (dbar)
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38˚
2001/07/07
144˚ 146˚ 148˚ 150˚
1300
1400
06 /01 /01 07 /01 /01 08 /01 /01 09 /01 /01
day
36˚
34 34.1 34.2 34.3 34.4 34.5 34.6 34.7 34.8 34.9 35
500
MMP ( eastward vel.), 5/23/01-9/26/01
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1100
10
0
1200
-10
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1600 25 31 5 10 15 20 25 30 5 10 15 20 25 31 5 10 15 20 25 31 5 10 15 20 25
34˚
MAY JUNE JULY AUGUST SEPTEMBER
2001
Fig. 8 Time series of salinity profile (top left) and zonal flow profile (bottom left) at 33.1N, 146.4E, and the sea surface
flow calculated by satellite altimetry on 7 July 2001. Depth range of the CTD profiler was between 550m and 1500m.
Observation term was from 23 May to 26 September 2001. On 7 July the Kuroshio Extension flowed southeastward
and the anticyclonic eddy existed just south of the current. At that time fresh water appeared at the mooring site,
where was a southern edge of the eddy.
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