Marine Ecosystems Research Department - jamstec japan agency ...

JAMSTEC 2002 Annual Report
Ocean Observation and Research Department
Observing System) and the fourth meeting POGO
(Partnership for Observation of the Global Oceans) ,
and had a research arrangement with many foreign
organizations concerned in order to realize WHP
revisits around the Southern Hemisphere.
135˚ 140˚ 145˚ 150˚ 155˚
40˚
35˚
1 m/s
(a) Wake Island Passage Experiment
In FY, we prepared for deep mooring observation
along a transect of the Wake Island Passage. We
call the deep mooring observation the Wake Island
Passage Experiment (WIPE), and it will start in .
We prepared mooring instruments and maintained
them for WIPE. Also we examined a method of in-situ
calibration of the mooring CTDs in order to acquire
accurate data. Mooring CTDs were attached to
CTD/RMS frame and CTD/RMS casts were performed
for simultaneous observation of CTD/RMS and mooring
CTDs. The mooring CTD data were compared with
more accurate CTD/RMS data to test in-situ calibration
of the mooring CTD data. Moreover, we prepared for
joint observation with Kyushu University in order to
strengthen the mooring current observation.
(b) Kuroshio Extension Experiment
An intensive observation was carried out in the
Kuroshio Extension region from April to September
. Three buoys consisting of current meters and
CTD were moored near the Kuroshio along -E,
where the first trough of the current path often stands.
An acoustic ocean tomography system was used to
monitor the change of background thermal distribution.
A total of six transceivers were deployed in April ,
and five were recovered in September. A mooring site
map of the intensive observation is shown in Fig. . In
FY the remaining transceiver and current meters
were recovered, and then data sets were made.
A temperature field was reconstructed from the
acoustic ocean tomography data using a first guess of
the sound field and an inversion technique. An example
of a calculated temperature field is shown in Fig. . The
Kuroshio off the east coast of Japan changed its path
Latitude
Latitude
30˚
Fig. 6 Mooring site map of Intensive Observation in the Kuroshio
Extension region. Circles indicate transceivers of acoustic
ocean tomography. Triangles indicate current meter mooring
sites. CTD profile measurement was made at the
southernmost current meter site. Arrows indicate sea surface
flow calculated by satellite altimetry on 7 July 2001.
The current of the Kuroshio Extension meandered and
there was a huge eddy at 144E south of the Kuroshio
Extension.
KE0516et of4 r100 or100 2 (100 m)
T6 e e c m
38
37
36
35
34
T1
33
T3
144 146T2
148 150
Longitude
T6
38
37
36
35
(500 m)
34
T1
33
T3
144 146T2
148 150
Longitude
22
21
20
19
18
17
16
15
14
13
12
11
10
14
13
12
11
10
9
8
7
6
5
4
3
2
T6
38
34
T1
33
T3
144 146T2
148 150
Longitude
T6
(1000 m)
38
frequently in . In the middle of May, the Kuroshio
was meandering and pitching off a huge cold eddy.
Another cold water region, seen east of N, E,
was the representation of another cold eddy which was
advecting from east to the Kuroshio Extension.
As reported in previous annual reports, especially
Latitude
Latitude
37
36
35
37
36
35
(300 m)
34
T1
33
T3
144 146T2
148 150
Longitude
Fig. 7 Temperature distribution in the Kuroshio Extension region
observed by acoustic ocean tomography system on 16
May 2001. Each panel shows the temperature at 100m
(top left), 300m (top right), 500m (bottom left) and 1000m
(bottom right). Notations T1 to T6 indicate the positions of
mooring and the lines between the transceivers indicate
sound paths.
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
5
4.5
4
3.5
3
2.5
2
38