**Measurements of the partial pressure of CO~2~ in near-surface seawater
and in marine boundary air**

(01 May 2008)

**Contributors:**

> Hisayuki Yoshikawa Inoue\* and Masao Ishii
>
> Geochemical Research Department, Meteorological Research Institute,
>
> 1-1 Nagamine, Tsukuba, Ibaraki 305-0052, Japan
>
> \*Current address:
>
> Laboratory of Marine and Atmospheric Geochemistry,
>
> Graduate School of Environmental Earth Science, Hokkaido University
>
> N10W5, Kita-ku, Sapporo 060-0810, Japan

**Ships:**

> Measurements have been made on onboard the following ships:
>
> RV Hakuho Maru I and II, Ocean Research Institute, the University of
> Tokyo
>
> RV Ryofu Maru II, Japan Meteorological Agency
>
> RV Natsushima, Japan Marine Science and Technology Center
>
> RV Kaiyo Maru, Japan Fisheries Agency
>
> MS Wellington Maru, Mitsui O.S.K. Lines
>
> RV Sogen Maru, Marine Biotechnology Institute
>
> TS Hokuto Maru, National Institute of Sea Training
>
> TS Taisei Maru, National Institute of Sea Training
>
> RV Kaiyo, Japan Marine Science and Technology Center
>
> RV Mirai, Japan Marine Science and Technology Center
>
> (see cruise list)

**Variables:**

> Variable_Name: mixing ratio of CO~2~ in dry air (*x*CO~2~)
>
> Description_of_Variable:　xCO~2~ in marine boundary air
> (*x*CO~2~\_Air) and *x*CO~2~ in air equilibrated with near-surface
> seawater (xCO~2~\_Sea).

**Equilibrator_Design:**

> Equilibrator_Type: shower-head
>
> Equilibrator_Volume: 1.5 dm^3^
>
> Water_Flow_Rate: ca. 6 -- 10 dm^3^ min^-1^
>
> Headspace_Gas_Flow_Rate: *ca*.500 -- 700 cm^3^ min^-1^
>
> Vented: Yes.

**Calibration_Gas:**

> Four cylinders of reference gases have been used to calibrate the
> output voltage of NDIR every 60 or 90 minutes. All reference gases
> used onboard underwent a pre- and post-cruise calibration against
> MRI-87 CO~2~ concentration scale of which primary standards consists
> of a series of primary standard gases made at Nippon Sanso Co. with a
> gravimetric method following the procedure reported by \[Tanaka, M.,
> T. Nakazawa and S. Aoki (1987): Time and space variations of
> tropospheric carbon dioxide over Japan. *Tellus*, **39B**, 3-12.\].
> The difference in CO~2~ concentration scale between WMO mole-fraction
> and MRI87 has tentatively been determined as Eq.(1):
>
> (*x*CO~2~^WMO^ -- *x*CO~2~^MRI87^) / ppm
>
> = -0.015 -- 0.569 · (*x*CO~2~^MRI87^--370) · 10^-2^ + 0.237 ·
> (*x*CO~2~^MRI87^--370)^2^ · 10^-4^
>
> \+ 0.341· (*x*CO~2~^MRI87^--370)^3^ · 10^-6^ (271 \< *x*CO~2~^MRI87^ /
> ppm \< 405)

**CO~2~\_Sensor:** Non-Dispersive Infrared (NDIR) Gas Analyzer

> Model: Beckman315A, 864, 865, 880, Rosemount Binos 4.1, LI-COR6251
>
> Environmental_Control: Temperature controlled within the instrument
> around the cell of the NDIR.
>
> CO~2~\_Sensor_Calibration: Once per hour or once per 1.5 hours using
> four standard gases.

**Warming_correction:**

> Correction of *p*CO~2~w in the equilibrator to the in situ *p*CO~2~sw
> for seawater warming (typically 0.0\< Δ*t*/ºC \<1.0 depending on the
> ship and location) was made using the equation given by \[Gordon and
> Jones (1973): The effect of temperature on carbon dioxide partial
> pressure in seawater. *Marine Chemistry*, **1**, 317 -- 322, 1973\] or
> \[Copin-Montegut, C. (1988): A New formula for the effect of
> temperature on the partial pressure of CO~2~ in seawater. *Marine
> Chemistry*, **25**, 29--37, and Copin-Montegut, C. (1989): A new
> formula for the effect of temperature on the partial pressure of CO~2~
> in seawater. Corrigendum. Marine Chemistry, **27**, 143 - 144.\] after
> mid-1990s.

**Method_References:**

> Inoue, H.Y., CO~2~ exchange between the atmosphere and the ocean:
> carbon cycle studies of the Meteorological Research Institute since
> 1968, *In: Dynamics and Characterization of Marine Organic Matter.,
> Eds. N. Handa, E. Tanoue and T. Hama., TERAPUB/Kluwer, Tokyo,* 509-53,
> 2000.
>
> See also the references in the cruise list.
>
> For at-sea intercomparison exercise, see Körtzinger, A., Mintrop, L.,
> Duinker, J. C., The international intercomparison exercise of underway
> *f*CO~2~ systems during the R/V *Meteor* cruise 36/1 in the North
> Atlantic Ocean. Environmental Science Division Publication No.4844,
> NDP-067, Carbon Dioxide Information Analysis Center, Oak Ridge
> National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn.,
> 1999.

**Data_Set_References:**

**Data_Set_Link:**

> Majority of the data in this data set have been archived at WMO's
> World Data Center for Greenhouse Gases: URL:
> <http://gaw.kishou.go.jp/wdcgg_j.html>. Data taken on board JAMSTEC's
> R/V Mirai are available from JAMSTEC's　MIRAI DATA WEB:
> URL:http://www.jamstec.go.jp/mirai/

**Cruise List**

[Ship Cruise Place Period PIs References]{.underline}

RV Hakuho Maru I KH68-4 N.Pac, eqPac, S.Pac, Southern Nov. 16, 1968 --
Feb. 28, 1969 Inoue, H. Y.\* 1, 11,18

KH70-1 N.Pac Feb. 6, 1970 -- Mar. 2, 1970 Inoue, H. Y.\* 1, 11

KH70-2 N.Pac Apr. 15, 1970 -- Jun. 17, 1970 Inoue, H. Y.\* 1, 11

KH83-4 N.Pac, eqPac, S.Pac, Southern Nov. 23, 1983 -- Feb. 22, 1984
Inoue, H. Y. 2, 4, 6, 11,18

KH85-3 N.Pac May. 31, 1985 -- Jun. 30, 1985 Inoue, H. Y.

KH88-1 N.Pac, eqPac, S.Pac, Jan. 22, 1988 -- Mar. 23, 1988 Inoue, H. Y.
7

RV Hakuho Maru II KH90-2 N.Pac, eqPac, S.Pac, Sep. 3, 1990 -- Oct. 25,
1990 Inoue, H. Y. Ishii, M. 8

KH90-3 N.Pac, eqPac Oct. 31, 1990 -- Dec. 13, 1990 Ishii, M. 8

KH94-4 N.Pac, eqPac, S.Pac, Southern Nov. 23, 1994 -- Feb. 13, 1995
Ishii, M. 11, 13, 15,18

KH01-3 N.Pac, eqPac, S.Pac, Southern Nov. 28, 2001 -- Jan. 21, 2002
Ishii, M. 18

RV Ryofu Maru II RY8301 N.Pac, eqPac Jan. 19, 1983 - Feb. 5, 1983 Inoue,
H. Y. 3, 4, 9, 19

RY8401 N.Pac, eqPac Jan. 21, 1984 - Feb. 8, 1984 Inoue, H. Y. 4, 6, 9,
19

RY8501 N.Pac, eqPac Jan. 18, 1985 - Feb. 6, 1985 Inoue, H. Y. 4, 9, 19

RY8601 N.Pac, eqPac Jan. 19, 1986 - Feb. 7, 1986 Inoue, H. Y. 9, 19

RY8701 N.Pac, eqPac Jan. 14, 1987 - Feb. 2, 1987 Inoue, H. Y. 5, 7, 9,
19

RY8706 N.Pac, eqPac Jun. 9, 1987 - Jul. 25, 1987 Inoue, H. Y. 7, 9, 19

RY8801 N.Pac, eqPac Jan. 16, 1988 - Feb. 4, 1988 Inoue, H. Y. 7, 9, 19

RY8901 N.Pac, eqPac Jan. 19, 1988 - Feb. 6, 1989 Inoue, H. Y. 7, 9, 19

RV Natsushima Na8701 N.Pac, eqPac Jan. 24, 1987 - Feb. 22, 1987 Inoue,
H. Y. 5, 7

Na8901 N.Pac, eqPac Dec. 28, 1988 - Feb. 21, 1989 Inoue, H. Y. 6

Na9001 N.Pac, eqPac Jan. 12, 1990 - Feb. 28, 1990 Inoue, H. Y., Ishii,
M. 9

Na9101 N.Pac, eqPac Dec. 28, 1990 - Mar. 10, 1991 Inoue, H. Y., Ishii,
M. 9

RV Kaiyo Maru Ki87 N.Pac, eqPac, S.Pac Oct. 28, 1987 -- Dec. 5, 1987
Inoue, H. Y. 6

MS Wellington Maru We8811 N.Pac, eqPac, S.Pac Nov. 4, 1988 -- Nov. 13,
1988 Inoue, H. Y. 6

RV Sogen maru 9110 N.Pac Oct. 8, 1991 -- Dec. 31, 1990 Inoue, H. Y.

TS Hokuto maru 9207 N.Pac, eqPac, S.Pac Jul. 4, 1992 -- Aug. 19, 1992
Inoue, H. Y.

9407 N.Pac Jul. 9, 1994 -- Aug. 28, 1994 Inoue, H. Y.

9601 N.Pac, Indian Jan. 20, 1996 -- Feb. 29, 1996 Inoue, H. Y.

9607 N.Pac Jul. 6, 1996 -- Aug. 27, 1996 Inoue, H. Y.

TS Taisei maru 9301 N.Pac, eqPac, S.Pac Jan. 25, 1993 -- Mar. 6, 1993
Inoue, H. Y.

9307 N.Pac, eqPac, S.Pac Jul. 5, 1993 -- Aug. 27, 1993 Inoue, H. Y. 15

9501 N.Pac, eqPac, S.Pac, Indian Jan. 23, 1995 -- Mar. 8, 1995 Inoue, H.
Y.

9801 N.Pac, eqPac, S.Pac Jan. 23, 1998 -- Mar. 7, 1998 Inoue, H. Y.

RV Kaiyo KY9307 eqPac Jan. 6, 1994 -- Feb. 17, 1994 Inoue, H. Y., Ishii,
M. 9,13,16

KY9406 N.Pac, eqPac Nov. 9, 1994 -- Jan. 31, 1995 Inoue, H. Y. 9,13,16

KY9511 eqPac Dec. 23, 1995 -- Jan. 19, 1996 Inoue, H. Y.

KY9601 eqPac Jan. 24, 1996 -- Feb. 24, 1996 Inoue, H. Y.

KY9701 eqPac Dec. 15, 1996 -- Jan. 22, 1997 Inoue, H. Y.

KY9702 eqPac Jan. 26, 1997 -- Feb. 27, 1997 Inoue, H. Y.

KY9714 eqPac Dec. 7, 1997 -- Dec. 24, 1997 Ishii, M. 11,16

KY9801 eqPac Jan. 3, 1998 -- Jan. 31, 1998 Ishii, M. 11,13

KY9901 eqPac Jan. 26, 1999 -- Feb. 28, 1999 Inoue, H. Y.

KY9909 eqPac Oct. 10, 1999 -- Nov. 21, 1999 Inoue, H. Y.

RV Mirai MR98test N.Pac, eqPac Jan. 31, 1998 -- Feb. 9, 1998 Inoue, H.
Y. 11,16

MR98K2 N.Pac, eqPac Dec. 24, 1998 -- Jan. 30, 1999 Ishii, M. 13,15,16

MR99K1 N.Pac, eqPac Feb. 8, 1999 -- Mar. 30, 1999 Inoue, H. Y.

MR99K6 N.Pac, eqPac Oct. 15, 1999 -- Nov. 18, 1999 Ishii, M.

MR99K7 N.Pac, eqPac Nov. 21, 1999 -- Dec. 25, 1999 Ishii, M. 15,16

MR00K8 N.Pac, eqPac Dec. 27, 2000 -- Feb. 6, 2001 Ishii, M. 15,16

MR01K1 N.Pac, eqPac Feb. 15, 2001 -- Mar. 21, 2001 Inoue, H. Y.

MR02K1 N.Pac, eqPac Jan. 7, 2002 -- Feb. 14, 2002 Inoue, H. Y. 16

MR02K2 N.Pac, eqPac Feb. 22, 2002 -- Mar. 29, 2002 Inoue, H. Y.

MR02K6 N.Pac, eqPac Nov. 14, 2002 -- Feb. 12, 2003 Ishii, M. 16

N.Pac: the North Pacific,

eqPac: the equatorial Pacific (10ºS -- 10ºN)

S.Pac: the South Pacific

Southern : the Southern Ocean

\* Reanalyzed from original data charts in 1998.

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**References**

1)  Miyake, Y., Sugimura, Y., Saruhashi. K., The carbon dioxide content
    in the surface waters in the Pacific Ocean. Records of Oceanographic
    Works in Japan, **12**, 45-52, 1974.

2)  Inoue, H., Y. Sugimura, Distribution of pCO~2~ and δ^13^C in the air
    and surface sea water in the Southern Ocean, south of Australia,
    *Mem*, *Natl. Inst. Polar Res., Spec. Issue*, **40**, 454-461, 1986.

3)  Fushimi, K.,Variation of carbon dioxide partial pressure in the
    western North Pacific surface water during the 1982/83 El Nino
    event, *Tellus*, **39B**, 214-227, 1987.

4)  Inoue, H., Y. Sugimura , K. Fushimi, pCO~2~ and δ^13^C in the air
    and surface sea water in the western North Pacific, *Tellus*,
    **39B**, 228-242, 1987.

5)  Inoue, H., Y. Sugimura, Distribution of the pCO~2~ in surface
    seawater of the western and central equatorial Pacific during the
    1986/87 El Nino/Southern Oscillation event, *Geophysical Research
    Letters*, **15**, 1499-1502, 1988.

6)  Inoue, H., Y. Sugimura, Distribution and variations of oceanic
    carbon dioxide in the western North Pacific, eastern Indian, and
    Southern ocean, south of Australia, *Tellus,* **40B**, 308-320,
    1988.

7)  Inoue, H. Y., Y. Sugimura, Variations and distributions of CO~2~ in
    and over the equatorial Pacific during the period from the 1986/88
    El Nino event to the 1988/89 La Nina event, *Tellus,* **44B**, 1-22,
    1992.

8)  Ishii, M., H. Y. Inoue, Air-sea exchange of CO~2~ in the central and
    western equatorial Pacific in 1990, *Tellus,* **47B**, 447-460,
    1995.

9)  Inoue, H. Y., H. Matsueda, M. Ishii, K. Fushimi, M. Hirota, I.
    Asanuma, Y. Takasugi, Long-term trend of the partial pressure of
    carbon dioxide (pCO~2~) in surface waters of the western North
    Pacific, 1984-1993, *Tellus,* **47B**, 391-413, 1995.

10) Inoue, H. Y., M. Ishii, H. Matsueda, M. Aoyama, Changes in
    longitudinal distribution of the partial pressure of CO~2~(pCO~2~)
    in the central and western equatorial Pacific, west of 160°W,
    *Geophysical Research Letters,* **23**, 1781-1784, 1996.

11) Inoue, H. Y., M. Ishii, H. Matsueda, S. Saito, T. Midorikawa, K.
    Nemoto, MRI measurements of partial pressure of CO~2~ in surface
    waters of the Pacific during 1968 to 1970 : re-evaluation and
    comparison of data with those of the 1980s and 1990s, *Tellus,*
    **51B**, 830-848, 1999.

12) Inoue,H., M. Ishii, H. Matsueda, S. Saito, M. Aoyama, T. Tokieda, T.
    Midorikawa, K. Nemoto,T. Kawano, I. Asanuma, K. Ando, T. Yano, A.
    Murata, Distributions and variations in the partial pressure of
    CO~2~ in surface waters (pCO~2~^w^) of the central and western
    equatorial Pacific during the 1997 / 1998 El Nino event, *Marine
    Chemistry,* **76**, 59-75, 2001.

13) Ishii, M., Y. Inoue, H. Matsueda, S. Saito, K. Fushimi, K.
    Nemoto, T. Yano, H. Nagai, T. Midorikawa, Seasonal variation in
    total inorganic carbon and its controlling processes in surface
    waters of the western North Pacific subtropical gyre, *Marine
    Chemistry,* **75**, 17-32, 2001.

14) Feely, R.A., J. Boutin, C.E. Cosca, Y. Dandonneau, J. Etcheto, H.Y.
    Inoue, M. Ishii, C.L. Quere, D.J. Mackey, M. McPhaden, N. Metzl, A.
    Poisson, R. Wanninkhof, Seasonal and interannual variability of
    CO~2~ in the equatorial Pacific, *Deep-Sea Research II,* **49**,
    2443-2469, 2002.

15) Ishii, M., H. Y. Inoue, H. Matsueda, Net community production in the
    marginal ice zone and its importance for the variability of the
    oceanic pCO~2~ in the Southern Ocean south of Australia, *Deep-Sea
    Research II,* **49**, 1691-1706, 2002.

16) Inoue, H.Y., M. Ishii, H. Matsueda, T. Kawano, A. Murata, Y.
    Takasugi, Distribution of the partial pressure of CO~2~ in surface
    water (pCO~2~^w^) between Japan and the Hawaiian Islands:
    pCO~2~^w^-SST relationship in the winter and summer, *Tellus,*
    **55B**, 456-465, 2003.

17) Ishii, M., S. Saito, T. Tokieda, T. Kawano, K. Matsumoto, H.Y.
    Inoue, Variability of surface layer CO~2~ parameters in the western
    and central equatorial Pacific, *Global Environmental Changes in the
    Ocean and on Land,Eds., M. Shiyomi, H. Kawahata. H. Koizumi, A.
    Tsuda, and Y. Awaya, TERRAPUB, Tokyo.* 59-94, 2004.

18) Inoue, H.Y., M. Ishii, Variations and trends of CO~2~ in the surface
    seawater in the Southern Ocean south of Australia between 1969 and
    2002, *Tellus*, **57B**, 58-69, 2005.

19) Midorikawa, T., K. Nemoto, H. Kamiya, M. Ishii, H.Y. Inoue,
    Persistently strong oceanic CO~2~ sink in the western subtropical
    North Pacific, *Geophysical Research Letters*, **32**, No. 5,
    L05612, 2005.