Hydrographic and Hydrochemical Time‐Series Observations along 137˚E and 165˚E sections by the Japan Meteorological Agency (JMA)
Yusuke Takatani
and Masao Ishii
(y‐[email protected])
(mishii@mri‐jma.go.jp)
Global Environment and Marine Department/JMA Geochemical Research Department/MRI
About 137˚E and 165˚E sections
JMA has been conducting a series of hydrographic and hydrochemical observations along meridional sections at 137˚E and 165˚E in the western
North Pacific. The 137˚E section extends from the tropics at 3˚N off New Guinea across the subtropical gyre to 34˚N near the southern coast of Japan.
On the other hand, the 165˚E section extends from the tropics at 8˚S off Solomon Islands across the subtropical and western subarctic gyre (WSG) to
50˚N near the Kamchatka. Each section extends across major currents (e.g. Kuroshio, North Equatorial Current (NEC), North Equatorial
Countercurrent (NECC), South Equatorial Current (SEC), etc.) and water masses (North Pacific Tropical Water (NPTW), North Pacific Subtropical
M d Water
Mode
W
(NPSTMW) North
(NPSTMW),
N h Pacific
P ifi Central
C
l Mode
M d Water
W
(CMW) North
(CMW),
N h Pacific
P ifi Intermediate
I
di
W
Water
(NPIW)) in
i the
h western North
N h Pacific.
P ifi
The observations along the 137˚E and 165˚E sections were started in 1967 and 1995, respectively. To understand the changes in oceanographic
structure and air‐sea interactions that are related to climate change in the North Pacific, these repeat surveys have been playing important roles.
R/V Ryofu‐maru
R/V Keifu‐maru
NPTW
NPSTMW
WHP‐P09 revisit
(2010, JMA)
Data available from http://cchdo.ucsd.edu/
pacific.html
NPIW
WHP‐P13 revisit
(2011 JMA)
(2011, JMA)
137˚EE
137
Measured parameters
To understand oceanographic structure and variability, only key parameters (e.g.
temperature, salinity, dissolved oxygen, nutrients, and etc.) had been initially
measured Afterward,
measured.
Afterward observations of carbonate chemistry (e.g.
(e g pCO2, DIC,
DIC pH
and Total Alkalinity) was also started.
Until 1988 discrete water samples had been collected with Nansen bottles fixed
on a cable from standard depths. Since 1989 a CTD‐rosette multisampler
mounted with Niskin bottles was introduced. Recently, continuous data in
dissolved oxygen and chlorophyll
chlorophyll‐aa have been also obtained by new sensors.
Currently, standard sea water and reference materials have been used in the
measurements of salinity, DIC, total alkalinity and nutrients. Measurements of
pCO2 have been made on WMO scales.
CTD-systems
History of Hydrographic Observation by JMA
Hydrographic Observation
Sampling System
Temperature
Bottle sampling
1967
NPSTMW
NPTW
NPSTMW
CMW
NPIW
CTD & bottle sampling
2008
Oxygen sensor (RINKO III)
1967
Nutrients
Kuroshio Extension
1988
Bottle sampling
Dissolved Oxygen
CMW
1994
DIC
2009
Total Alkalinity
NPTW
1967
NPIW
NEC
SEC
1988
Nansen Bottles
CTD‐rosette multisampler
1967
1988
CTD
reversing mercury thermometer
2010
Deep Ocean Standard Thermometer (SBE35)
1967
Salinity
WSG
NECC
1967
Glass electrode
pH
1994
CFCs
165˚E
˚
1967
(irregular)
Bottle sampling
Chlorophyll‐a
New Guinea Coastal Current
2007
2003
spectrophotometric
2010
Chlorophyll sensor
Underway
The repeat
p
hydrographic
y g p sections alongg 137˚E and 165˚E,, and major
j currents in the
western North Pacific (middle). Time‐Latitude distributions of observations along
137˚E (left) and 165˚E section (right).
yp
vertical sections alongg 137˚E (top)
( p) and 165˚E section (bottom).
(
)
Typical
Shading denotes salinity and black (white) contour line denote
temperature (potential density).
Fluorescence
Nakano et al (2007, GRL)
Nakano et al.
(2007 GRL)
DOT 01X
DOT-01X
Automatic photometric titrator DOT‐01X (KIMOTO Electronic, JAPAN)
Modified Carpenter’s method Nutrients
Auto Analyzer III (BLTEC, JAPAN)
Reference Material of Nutrients in seawater (KANSO)
Dissolved Inorganic Carbon (DIC)
i l d
i
b ( )
Coulometric titration method (Nippon ANS, JAPAN)
Certified Reference Material (SIO) AA III
Total Alkalinity (TA)
Spectrophotometric determination using indicator dye (Nippon ANS, JAPAN)
Certified Reference Material (SIO)
pH
Spectrophotometric determination using indicator dye (Nippon ANS, JAPAN)
Certified Reference Material (SIO) (calculated from certified DIC and TA) Chlorofluorocarbon (CFCs)
Purge and trap extraction and ECD‐GC determination method (GL Sciences, JAPAN )
Standard Gas determined by gravimetric method (TAIYO Nippon SANSO, JAPAN)
Chlorophyll‐a
p y
10‐AU Field Fluorometer (Turner Designs, USA)
Underway
Thermosalinograph (TSG)
[Temperature] SBE 38 (Sea‐Bird, USA)
[Salinity] SBE 45 (Sea‐Bird, USA)
DIC-TA
DIC
TA measuring systems
pCO2
Underway pCO2 analysis with shower-head equilibrator (Nippon ANS, JAPAN)
WMO mole fraction scale
pH measuring systems
Chlorophyll‐a
10-AU Field Fluorometer (Turner Designs, USA)
pCO2 measuring
systems
Public information on the JMA web site P bli i f
ti
th JMA b it
Carbon Parameters
DO decreases along 137˚E section
T k t i et al.
Takatani
t l (2012, GBC)
(2012 GBC)
Linear trends from 1967 to 2005
(a) salinity
(b) potential temperature
(c) salinity
(d) depth of isopycnal surface
(a) and (b) is against the depth
ordinate, (c) and (d) is against the
potential density ordinate.
The potential temperature decreased (increased) above
(below) the salinity minimum along 165˚E section
Salinity
Guildline AUTOSAL 8400B (Guildline, Canada)
Standard Sea Water (IAPSO)
Dissolved Oxygen (DO)
1995
Many reports by using the time‐series data along the 137˚E and 165˚E sections!!
M
t b
i th ti
i d t l
th 137˚E d 165˚E
ti !!
Mid‐depth freshening along 137˚E section
Water Column Chemical Measurements
CFCs measuring systems
Dissolved Oxygen
Linear trends of DO
(mol/kg/yr) from 1985 to
2010 on each isopycnal
surface.
DO decrease along 165˚E section
Long‐term trends of pCO2 and pH in surface
Midorikawa et al.
et al (2010, Tellus)
(2010 Tellus)
waters along 137
137˚EE
Time‐series of pCO2air,
pCO2sea (left),
and pH
(right) at six latitudes along
137˚E in winter.
●:3˚N, ▲:10˚N, ◆:15˚N, ■:20˚N, ▲: 25˚N, ●:30˚N.
Ocean acidification off the south coast of Japan
Sasano (in preparation)
SBE 35
1983
Outcome of Time‐Series Observation Temperature & Salinity
Temperature
SBE 3plus (Sea‐Bird, USA)
SBE 35 (Deep Ocean Standard Thermometer) (Sea‐Bird, USA)
Salinity (conductivity)
SBE 4C (Sea‐Bird, USA)
Dissolved Oxygen
RINKO III (JFE Advantech, JAPAN)
Chlorophyll‐a
RINKO III
Chlorophyll Fluorometer (Seapoint, USA)
1995
Thermosalinograph
g p
pCO2
Instrument and Standards
CTDO2
Ishii et al. (2011, JGR)
Kouketsu et al. (2010, DSR II)
Data of oceanographic and marine observations are available from
the JMA web site (http://www.data.kishou.go.jp/kaiyou/db/
vessel_obs/data‐report/html/ship/ship_e.php). In addition, we have
reported information for oceanic carbon cycle (http://www.data.
kishou go jp/kaiyou/english/oceanic carbon cycle index html)
kishou.go.jp/kaiyou/english/oceanic_carbon_cycle_index.html).
In
the future, we are going to publish information for ocean
acidification, and improve for column inventory of oceanic carbon
dioxide.
Ocean acidification along 137˚E section
Long‐term trends of pH (left)
and Ωaragonite (right) in surface
sea water at 10, 20, 30˚N along
the 137˚E in winter.
pH
and
Ωaragonite
were
estimated from pCO2 assuming
total alkalinity is constant.
Increase of preformed nDIC along 137˚E section
Ishii (in preparation)
Potential temperature trend (˚C/yr)
from 1996 to 2007 on neutral
density along 165˚E. Gray curve is
the 34.2 contour for salinity. Green
curves denote the late winter
mixed‐layer density.
Linear trends
Li
t d
off DO
(mol/kg/yr) from 1987 to
2011 on each isopycnal
surface
Seasonally detrended time‐
series of carbon parameters
in surface water north of
the Kuroshio axis at 137˚E.
Long‐term trends of (a) the
salinity‐ normalized DIC (nDIC),
(b) AOU and (c) preformed
nDIC on isopycnal surfaces at
30˚N along the 137˚E section.
Preformed nDIC
= (DIC – 117/170 * AOU) * 35/S