Transcript
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
