Marine Chemistry 72 Ž2000. 297–315
www.elsevier.nlrlocatermarchem
Increase in the uptake rate of oceanic anthropogenic carbon in the
North Pacific determined by CFC ages
Yutaka W. Watanabe a,) , Tsuneo Ono b,1, Akifumi Shimamoto c
a
National Institute for Resources and EnÕironment, 16-3 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
b
National Research Institute of Fisheries Science, Yokohama, Kanagawa 236-8648, Japan
c
KANSO Co. Ltd., Osaka 541-0052, Japan
Received 21 May 1999; received in revised form 6 March 2000; accepted 7 August 2000
Abstract
We propose an approach to estimate the rate of increase of oceanic anthropogenic carbon inventory with CFC11 dating
technique. This approach relies on the elapsed time from when the water lost contact with atmosphere as determined by CFC
age. Furthermore, the assumption is made that it remains constant over a decadal time scale. Finally, we consider only the
increase in anthropogenic carbon from one decade to another and not the entire change from the pre-industrial period to the
present. The advantages and disadvantages of our approach are discussed. Using this approach, the spatial distributions of
the rate of increase of the anthropogenic carbon inventory and the uptake rate of anthropogenic carbon in the North Pacific
were obtained. The western North Pacific subtropical region exhibited a maximum in the rate of increase of the
anthropogenic carbon inventory of more than 8 g C my2 yeary1 during 1988–1998, which was equivalent to 34% of the
total uptake rate in the entire North Pacific. The net total uptake rate of anthropogenic carbon in the whole North Pacific
increased with time and was 0.55 " 0.09 Pg C yeary1 during 1988–1998 indicating that the North Pacific absorbs 24% of
the whole oceanic uptake of anthropogenic carbon. q 2000 Elsevier Science B.V. All rights reserved.
Keywords: Anthropogenic carbon inventory; CFC; North Pacific
1. Introduction
)
Corresponding author. Tel.: q81-298-61-8391; fax: q81-29861-8357.
E-mail addresses: [email protected] ŽY.W. Watanabe.,
[email protected], [email protected] ŽT. Ono .,
[email protected] ŽA. Shimamoto..
1
Present address: Ecosystem Change Research Program, Frontier Research System for Global Change ŽFRSGC., 1-18-16,
Hamamatsu-cho, Minato-ku, Tokyo 105-0013, Japan.
When considering the present balance of an anthropogenic carbon, it is necessary to determine how
much of the anthropogenically produced carbon the
ocean absorbs and where the carbon accumulates in
the ocean. The spatial distribution of anthropogenic
carbon, although estimated by various recent models,
shows that both the inventory and uptake rate differ
significantly between models. Thus, it is difficult to
know the reliability of the results ŽSarmiento et al.,
1992; Siegenthaler and Joos, 1992; Maier-Reimer,
0304-4203r00r$ - see front matter q 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 3 0 4 - 4 2 0 3 Ž 0 0 . 0 0 0 8 7 - 6
298
Y.W. Watanabe et al.r Marine Chemistry 72 (2000) 297–315
1993; Orr, 1993; Siegenthaler and Sarmiento, 1993;
Stocker et al., 1994.. On the other hand, new observational data-based approaches, like direct DIC comparison approach ŽWallace and Johnson, 1994; Slansky et al., 1997; Peng et al., 1998; Ono et al., 1998,
2000a; Sabine et al., 1999a,b. and C-13 approach
ŽQuay et al., 1992. during any decadal interval, have
been proposed. Unfortunately, at present, these approaches are limited in use due to the insufficient
quality of the historical data and also the insufficient
spatial distribution of the data available, which can
be partially overcome using multiple regression techniques ŽSlansky et al., 1997.. Overall, these methods
can only give a rough estimate with a large potential
error.
Brewer Ž1978. and Chen and Millero Ž1979. first
proposed the back calculation approach to estimate
the oceanic anthropogenic carbon content. In this
approach, the anthropogenic carbon content can be
estimated by correcting the observed DIC for the
change incurred due to the remineralization of organic matter and the dissolution of CaCO 3 . Using
this method, many studies have been carried out
ŽChen and Pytkowicz, 1979; Chen, 1982, 1993; Goyet
and Brewer, 1993; Tsunogai et al., 1993.. However,
this method has not been generally considered appropriate, because the potential errors associated with its
estimates were regarded as too large. The uncertainties of this method are related to the mixing of
different water masses with unknown initial concentration of DIC, TA and O 2 , the difficulty of choosing
an appropriate DIC content for the pre-industrial
period, the assumptions of constant stoichiometric
ratios, P:N:C:-O 2 , and the use of AOU for determining the contribution of the remineralization of organic matter ŽShiller, 1981, 1982.. Although Goyet
et al. Ž1999. proposed an approach that combined the
above methods and the use of end member water
mixing to overcome the mixing problem. There is
still the difficulty of selecting the parameters of the
initial end members with their method.
Gruber et al. Ž1996. and Gruber Ž1998. improved
the above methods based on Brewer Ž1978. and
Chen and Millero Ž1979.. Their main improvements
are that Ž1. the source of performed alkalinity is
represented as a one function using a multiple regression technique between H 3 PO4 , O 2 and salinity,
and Ž2. the concept of air–sea equilibrium to deter-
mine the DIC content of the pre-industrial period and
the air–sea disequilibrium on isopycnal surfaces are
introduced. This introduction overcomes the water
mixing problem and the difficulty of choosing an
appropriate value for the DIC content of the pre-industrial period. Furthermore, it allows the distribution of the entire anthropogenic carbon inventory
from the pre-industrial period to the present to be
described. With this method, Gruber et al. Ž1996.
and Gruber Ž1998. estimated the distribution of the
entire anthropogenic carbon inventory in the Atlantic. Similar studies have been carried out in the
Indian and Pacific Oceans ŽSabine et al., 1999a,b;
Feely et al., 1999..
However, the method of Gruber only describes
the entire anthropogenic carbon inventory from the
pre-industrial period to the present and cannot be
used to estimate the rate of increase of the anthropogenic carbon from one decade to another. Their
estimation also has the problem that it depends largely
on the values of the stoichiometric ratios, P:N:C:-O 2
estimated from Anderson and Sarmiento Ž1994.. The
problem with these ratios is that they scatter largely
in the top layer of about 400 m, where most of the
atmospheric anthropogenic carbon is absorbed. Thus,
there are still so large potential errors associated with
this method. Furthermore, Gruber et al. Ž1996. also
derive simple equation to calculate the oceanic anthropogenic carbon mainly using the dating technique as a by-product of this method. They did not
use this equation based on CFC dating technique
because of the potential errors with regard to the age
of water masses.
However, if we consider here only the changes of
anthropogenic carbon from one decade to another,
this simple CFC dating technique may be useful to
estimate the rate of increase of oceanic anthropogenic carbon content and the oceanic uptake rate.
Also, without complicated assumptions andror equations such as those relating to the constant stoichiometric ratios, and without the use of AOU for determining the contribution of the remineralization of
organic matter, we can deduce information on the
oceanic anthropogenic carbon distribution and uptake rate. Therefore, we have attempted to improve
the Gruber approach, and show the advantages and
disadvantages of our approach, and apply this method
to the North Pacific.
Y.W. Watanabe et al.r Marine Chemistry 72 (2000) 297–315
2. Methods
2.1. Concepts of the preÕious approaches for anthropogenic carbon and their problems
2.1.1. Back-calculation approach for the estimation
of the entire oceanic anthropogenic carbon inÕentory
The black-calculation approach is one of the
strategies to estimate the increase of the entire anthropogenic carbon inventory from the pre-industrial
period to the present ŽBrewer, 1978; Chen, 1993..
The concept is summarized as follows ŽChen, 1982.:
0
C anth s C 0 y C pre
0
s C obs y DC carb y DC org y C pre
s C obs y 0.5 Ž TAobs y TA0 .
0
y R C :O 2Ž O 2obs y O 2sat . y C pre
,
Ž 1.
where C anth is the increase of DIC due to anthropogenic carbon influx into the ocean; the superscript
A0B represents the initial concentration at the time
when the water lost contract with atmosphere; C obs ,
TAobs , O 2obs are the observed DIC, total alkalinity
0
and dissolved oxygen; C pre
is the initial DIC of the
water in the pre-industrial period; DC carb is the
change in DIC due to the production and dissolution
of CaCO 3 ; DC org is the change in DIC due to the net
production and remineralization of organic matter,
R C:O 2 is the appropriate stoichiometric ratio for car0
bon remineralization to oxygen utilization. Since C pre
cannot be determined directly from the observational
data, it was estimated as follows:
0
0
C pre
s C present
yX,
Ž 2.
0
where C present
and X represent, respectively, the
initial DIC of the present sea surface, and the quantitative change in DIC at the surface between the
0
is
present day and the pre-industrial period. C pre
determined by assuming that the deep water has not
been affected by the atmospheric anthropogenic carbon influx. All quantities, except O 2 , are normalized
0
to a salinity of 35. Then both C present
and TA0 are
determined by linear functions of potential temperature, based on the relationships of C obs and TAobs
versus temperature at the present-day sea surface.
299
The major problems of this approach are that the
potential errors associated with the estimates may be
regarded as too large for the following reasons: the
mixing of water masses from different origin with
unknown different initial concentrations of DIC, TA,
and O 2 ; the difficulty of choosing an appropriate
DIC content for the pre-industrial period; the assumptions related to the constant stoichiometric ratios, R, and the use of AOU for determining the
contribution of the remineralization of organic matter
ŽShiller, 1981, 1982..
2.1.2. ImproÕed back-calculation approach for the
estimation of the entire oceanic anthropogenic carbon inÕentory
Thus, Gruber et al. Ž1996. and Gruber Ž1998.
improved the above approach proposed by Brewer
Ž1978. and Chen and Millero Ž1979., to overcome
the water mixing problem and the difficulty of
0
choosing an appropriate C pre
. Their main improvements of this approach were that the anthropogenic
carbon content was calculated on isopycnal surfaces,
that a source of TA0 was represented as one function
equation using a multiple regression technique between H 3 PO4 , O 2 and S, and that the sea equilibrium content with the air at 280 matm were used to
determine the DIC content for the pre-industrial period. Gruber et al. Ž1996. and Gruber Ž1998. also
introduced the concept of the air–sea disequilibrium
of CO 2 to get the actual anthropogenic carbon as
follows:
0
C anth s Ž C obs y DC carb y DC org . y C pre
y C diseq
s C obs y 0.5 TAobs y TA0
qR N :O 2Ž O 2obs y O 2sat . 4 y R C :O 2Ž O 2 y O 2sat .
y C eq Ž S, T , TA0Ž S , PO . , f CO 2Ž280 matm . .
y C diseq ,
Ž 3.
where the subscripts, AeqB and AdiseqB denote the
air–sea equilibrium condition and the air–sea disequilibrium condition, respectively. Both R C:O 2 and
R N:O 2 are the appropriate stoichiometric ratios for
carbon and nitrogen remineralization to oxygen utilization; S, T, f CO 2Ž280 matm. are, respectively, the
300
Y.W. Watanabe et al.r Marine Chemistry 72 (2000) 297–315
salinity and potential temperature Ž8C., and the fugacity of atmospheric CO 2 of 280 matm expected in
the pre-industrial period. TA 0Ž S, PO. is the performed
total alkalinity represented as one function equation
using a multiple regression technique between S,
H 3 PO4 and O 2 . They also used the following equations for estimating C diseq by transforming Eq. Ž3..
For deep ocean density surfaces in regions far way
from the outcrop where the atmospheric anthropogenic carbon is assumed not to have influxed.
0
C diseq s Ž C obs y DC carb y DC org . y C pre
.
Ž 4.
For shallower surfaces, the intermediate, and deep
ocean density in regions near the outcrop where the
atmospheric anthropogenic carbon is assumed to have
already influxed, above 2000 m,
C diseq s Ž C obs y DC carb y DC org . y C eq
s C obs y 0.5 TAobs y TA0Ž S , PO.
qR N :O 2Ž O 2obs y O 2sat . 4 y R C :O 2Ž O 2 y O 2sat .
y C eq Ž S, T , TA0Ž S , PO. , f CO 2Ž ty t . . ,
Ž 5.
where t and t are the sampling date, and the elapsed
time since the water mass lost contact with the
atmosphere, respectively.
Gruber et al. Ž1996. estimated C anth by deducing
Eq. Ž4. or Eq. Ž5. from Eq. Ž3.. However, these
calculations of C anth are complicated and have an
error of the order of 13 mmol kgy1 for the anthropogenic carbon content with potential errors of all
quantities such as TA0Ž S, PO. , R N:O 2 , R C:O 2 and C diseq .
The error is equivalent to about one fourth of C anth
near the surface at the present.
Here, substituting Eq. Ž5. in Eq. Ž3., the entire
increase of anthropogenic carbon from the pre-industrial period to the present can be simply expressed as follows.
2.1.3. Approach for the estimation of the rate of
increase of the oceanic anthropogenic carbon
Focusing only on the rate of increase of the
anthropogenic carbon content from one decade to
another and not the entire increase from the pre-industrial period to the present, it is possible to use an
improved Eq. Ž6. as follows:
DC anthŽD t . s Ž C anthŽ tqD t . y C anthŽ t . . rDt
½C
s
eqŽ tqD t .
Ž S, T , TA0Ž S . , f CO2Ž tqD ty t . .
yC eq Ž S, T , TA0Ž S . , f CO 2Ž280 matm . .
5
y C eqŽ t . Ž S, T , TA0Ž S . , f CO 2Ž ty t . .
½
yC eq Ž S, T , TA0Ž S . , f CO 2Ž280 matm . .
5
rDt
C anth s C eq Ž S, T , TA0Ž S , PO. , f CO 2Ž ty t . .
y C eq Ž S, T , TA0Ž S , PO. , f CO 2Ž280 matm . .
potential errors of C anth . However, Gruber et al.
Ž1996. did not use Eq. Ž6. to estimate the increase of
the entire anthropologenic carbon content from the
pre-industrial period to the present. The main reason
that they considered was that the potential errors
with regard to the age of the water masses would
enter directly into the estimate. If the water ages
deviate by 3 years, C anth has a potential error of
about 3 mmol kgy1 , which is equivalent to about one
tenth of the C anth near the surface. The deviation of
TA0 of 10 mmol kgy1 also brings about a potential
error of 0.3 mmol kgy1 for C anth , which is smaller
than the error due to the water age. Furthermore,
using the CFC dating techniques, one cannot estimate C anth before the 1950s due to the small concentration oceanic CFC present before the 1950s. Thus,
it is difficult to obtain the entire anthropogenic carbon inventory from the pre-industrial period to the
present. Unfortunately, Gruber et al. Ž1996. and Gruber Ž1998. did not use Eq. Ž6..
Ž 6.
Because this equation does not include R N:O 2 ,
R C:O 2 and C diseq and it is simple calculation that
mainly relies on t , it is possible to reduce the
s C eqŽ tqD t . Ž S, T , TA0Ž S . , f CO 2Ž tqD ty t . .
½
yC eqŽ t . Ž S, T , TA0Ž S . , f CO 2Ž ty t . . rDt ,
5
Ž 7.
Y.W. Watanabe et al.r Marine Chemistry 72 (2000) 297–315
where DC anthŽD t . is the rate of increase of the anthropogenic carbon content during any period Ž D t . after
the pre-industrial period. TA0Ž S . is the preformed
total alkalinity represented as a single function equation using only S and not the multiple regression
technique between S, H 3 PO4 and O 2 . Thus,
DC anthŽD t . can be used without nutrient data and their
appropriate stoichiometric ratios that can potentially
cause large errors. To assess to what extent our
approach is useful, we calculated DC anthŽD t . based on
the solubility of CO 2 ŽWeiss, 1974., the dissociation
constants of CO 2 and of boric acid ŽWeiss, 1974;
Dickson and Goyet, 1994; Uppstrom, 1974., the
dissociation constants of CO 2 and of boric acid
ŽWeiss, 1974; Dickson and Goyet, 1994; Uppstrom,
1974., the atmospheric history of CO 2 ŽSarmiento et
al., 1992; Keeling and Whorf, 1999.. The potential
errors of water age, TA0 , and the other parameters
were estimated in Section 2.2.
2.2. Error estimations
301
of ages during the last five decades in the North
Pacific. They estimated the difference between
CFC11 and CFC12 ages to be 3 years.
Substituting this dating error into Eq. Ž7., the
potential error of CFC dating techniques to the estimate of DC anthŽD t . is about 0.05 mmol kgy1 yeary1 .
This is a maximum deviation of DC anthŽD t . during the
period from the 1950s to the present time. It is
equivalent to about 5% of the rate of increase of the
anthropogenic carbon content expected from the atmospheric CO 2 increase in the 1990s ŽFig. 1..
2.2.2. SensitiÕity of DC a n t h( D t) to preformed alkalinity
Millero et al. Ž1998. showed the existence of a
linear relationship between the surface total alkalinity and the salinity in the Pacific, Atlantic and Indian
oceans. replacing the surface total alkalinity with
TA0 , the relationship for the whole Pacific is expressed as follows:
TA0 s 399 q 54.629S,
2.2.1. SensitiÕity of DC a n t h( D t) to dating technique
errors
Doney et al. Ž1997. have shown that CFC12 and
3
H– 3 He allow estimations of ages in the North
Atlantic which agree within a few years for ages less
than 50 years. Watanabe et al. Ž1999. also have
shown that CFC11, CFC12, CFC113, SF6 , CFC113r
CFC11 and CFC113rCFC12 allowed the estimation
Ž standard deviations 12 mmol kgy1 . .
Ž 8.
Substituting this deviation of 12 mmol kgy1
yeary1 . This is a maximum deviation of DC anthŽD t .
during the period from the 1950s to the present time.
This is equivalent to less than 1% of DC anthŽD t .
expected from the atmospheric CO 2 increase in the
1990s.
Fig. 1. Atmospheric history of CO 2 based on observational data ŽSarmiento et al., 1992; Keeling and Whorf, 1999..
302
Y.W. Watanabe et al.r Marine Chemistry 72 (2000) 297–315
This means that DC anthŽD t . is not sensitive to the
change of TA0 because we are considering only the
rate of increase of the anthropogenic carbon content
from one decade to another and not the entire increase from the pre-industrial period to the present.
Even if we used relationship for TA0 other than Eq.
Ž8., C anth would deviate largely from that estimated
by Eq. Ž8., but DC anthŽD t . would only change negligibly. Even if the difference in the absolute value of
TA0 between any two relationships is 100 mmol
kgy1 , the difference in TA0 would only be about
0.03 mmol kgy1 yeary1 as a maximum deviation of
DC anthŽD t . .
2.2.3. SensitiÕity of DC a n t h( D t) to salinity and temperature
The water age estimated by CFC11 would not
change because the air–sea equilibrated time of CFCs
is about 1 month, which is shorter than each seasonal
period. On the other hand, both salinity and temperature have seasonal change in the surface mixed layer
above 100-m depth, which are affecting DC anthŽD t . .
Substituting the mean seasonal variability of salinity
of 0.5 and temperature of 58C in the North Pacific in
Eq. Ž7., the effect on the estimate of DC anthŽD t . is
0.05 mmol kgy1 yeary1 as a maximum deviation of
DC anthŽD t . for salinity change, and 0.01 mmol kgy1
yeary1 for temperature change, respectively. These
deviations for salinity and temperature are equivalent
to about 5% and 1%, respectively, of the rate of
increase of the anthropogenic carbon content expected from the atmospheric CO 2 increase in the
1990s. However, the seasonal changes in salinity and
temperature near the surface cannot affect the
DC anthŽD t . in the intermediate and deep water because the thickness of the surface mixed layer is
about 100 m.
2.2.4. Total error of DC a n t h( D t) in our approach
As in the above sections, we estimated the potential errors of DC anthŽD t . due to water ages, TA0 , S
and T. The most important parameters are the dating
error and the salinity change. Adding up all the
errors, the entire potential error of DC anthŽD t . was
estimated to be 0.12 mmol kgy1 yeary1 as the
maximum deviation of DC anthŽD t . . This is equivalent
to about 10% of DC anthŽD t . expected from the atmospheric CO 2 increase in the 1990s.
2.3. DisadÕantages and assumptions on our approach
2.3.1. Air–sea disequilibrium of anthropogenic carbon
Using our approach, it is possible to calculate
simply the rate of increase of the anthropogenic
carbon content from one time to another with a
potential error of 0.12 mmol kgy1 yeary1 . However,
some assumptions have to be made to estimate
DC anthŽD t . because our approach has some disadvantages.
One of them is an assumption that the change in
C diseq is neglected to lead to Eq. Ž6.. Although it is
not true in actual ocean, the change in C diseq is
relatively small over most of the oceans, except at
locations of strong upwelling and in the high latitudes like the Southern Ocean ŽSarmiento et al.,
1992.. In the Atlantic and Indian Oceans, Gruber et
al. Ž1996., Gruber Ž1998. and Sabine et al. Ž1999a.
found that C diseq was almost constant over time with
large deviations. This suggests that it is possible to
apply our assumption to the Pacific.
2.3.2. Inter-annual Õariability of water masses
A second problem is that we cannot consider the
inter-annual variability of water masses, especially
near the surface. This effect is a common problem
with all previous back calculation approaches and
the direct DIC comparison approach, andror the
model calculations. To assess this effect, extensive
repeat observations are required. Here, we assume
that the inter-annual variability of water masses remains constant with time.
2.3.3. Entire anthropogenic carbon inÕentory from
the pre-industrial period to the present
The next problem is that the entire anthropogenic
carbon inventory from the pre-industrial period to
the present time cannot be estimated from recent
artificial products like CFCs. CFCs are useful tools
to clarify the behaviour of water masses during the
last several decades. Here, we used CFC11 to calculate t because many CFC11 data sets exist for the
Pacific and CFC11 sensitivity is higher than that of
CFC12 and CFC113. Using a CFC11 concentration
of more than 0.02 pmol kgy1 , which is close to the
detection limit of CFC11, the CFC11 age is equal to
Y.W. Watanabe et al.r Marine Chemistry 72 (2000) 297–315
1950 AD. Although the estimation of t from lower
concentration of CFC11 have a problem due to
mixing of water masses, in that case, advection
would control the transport of water masses and its
mixing effect has been estimated to be small in the
North Pacific and the North Atlantic during the last
several decades ŽWatanabe et al., 1994; Warner et
al., 1996; Gruber, 1998.. Here, we attempted to
calculate i of water masses having CFC11 of more
than 0.02 pmol kgy1 , based on the time history of
atmospheric CFC11 concentration Žpptv. and its solubility ŽWarner and Weiss, 1985; Doney and Bullister, 1992; NOAA, 1999..
Therefore, due to the use of CFC11, it is not
possible to get C anth before the 1950s and the entire
oceanic anthropogenic carbon inventory from the
pre-industrial period to the present time. However,
the most important point about our approach is that
we consider only the rate of increase of the anthropogenic carbon from one decade to another and not
the entire increase from the pre-industrial period to
the present, and we can get the rate of increase of the
anthropogenic carbon inventory and its uptake rate.
Furthermore, we need to consider the extent of
the rate of increase of the oceanic anthropogenic
carbon in the deep water with no CFC11. Atmo-
303
spheric anthropogenic carbon has been increasing
since around 1800, i.e., before the active industrial
release of CFC11, which occurred in the 1950s ŽFig.
1.. While the steep rate of increase of atmospheric
CO 2 was after 1950, the rate of increase was slow
before 1950. Thus, DC anthŽD t . before 1950 is expected to be small. Applying our approach to the
deep water with less than 0.02 pmol kgy1 of CFC11
in the Pacific ŽFig. 2., DC anthŽD t . during the period
from 1800 to 1950 was estimated to range from 0.05
to 0.15 mmol kgy1 yeary1 , thus almost within the
0.12 mmol kgy1 yeary1 of our approach error. The
thickness of water having DC anthŽD t . before 1950 is
thinner than that after 1950, because the radiocarbon
age of the deep water below 2000 m in the Pacific is
extremely old and estimated between 1000 and 2000
years ŽTsunogai, 1981., and the vertical diffusive
effect is also small in the deep water ŽWarner et al.,
1996; Gruber, 1998.. Therefore, the period from
1800 to 1950 has a small contribution to the rate of
increase of the anthropogenic carbon inventory
Ž HDC anthŽD t . d z . in the whole water column in the
Pacific, and our estimation at the basin scale is
considered to be a minimum value.
On the other hand, if our approach is applied to
locations where the vertical gradient in age of water
Fig. 2. Distributions of a water depth with CFC11 of 0.02 pmol kgy1 in the Pacific Žm..
304
Table 1
List of calculation parameters, equations and references used in this study
Terms
Calculation for water age
Atmospheric history of CFC11
Equilibrium of CFC11 partial pressure
Solubility function of CFC11
Elapsed time
Figures and equations
References
Fig. 1
Sarmiento et al., 1992; Keeling and Whorf, 1999
Weiss, 1974
Dickson and Goyet, 1994; Uppstrom, 1974
Millero et al., 1998
Eq. Ž8.
TA0 s 399q54.629S
pCFC Ž t . sC obs r aŽ S, T .
aŽ S, T .
t s t 0 y t,
where t is the water age,
t 0 is the date of sampling
Calculation for the rate of increase of the oceanic anthropogenic carbon
CFC11, salinity, water temperature data
Increase of the entire anthropogenic carbon
Eqs. Ž1., Ž3. and Ž6. C anth
content from the pre-industrial period
to the present time
Rate of increase of the anthropogenic carbon
Eq. Ž7.
DC anthŽD t . s C eqŽ tqD t .
Ž S, T, TA0Ž S . , f CO 2Ž tqD ty t . .
content from one decadal to another
yC eqŽ t .Ž S, T, TA0Ž S . , f CO 2Ž ty t . .4rD t
Time interval
D t s10 years
Period
1968–1978, 1978–1988, 1988–1998 ŽAD.
Rate of increase of anthropogenic carbon
H CF C11s0.02r DC anthŽD t . d z
inventory from the pre-industrial
period to the present time
C11s0.02
Uptake rate of anthropogenic carbon in each area
D u CF
s aŽ H CFC11s0.02r DC anthŽD t . d z .ave
anthŽD t .
where a is the area of each region
C11s0.02 .
Total uptake rate of anthropogenic carbon
ÝŽ aD u CF
anthŽD t .
in the whole North Pacific
Doney and Bullister, 1992; NOAA, 1999
Doney and Bullister, 1992
Warner and Weiss, 1985
See Table 2 and Fig. 4
Chen, 1982; Gruber et al., 1996
This study
This study
This study
This study
This study
This study
Y.W. Watanabe et al.r Marine Chemistry 72 (2000) 297–315
Calculation for CO2
Atmospheric history of CO 2
Solubility of CO 2
Dissociation constants of CO 2 and boric acid
Preformed total alkalinity
Cruise name
Sampling date
Sampling area
Number of
stations
Depth
Reference
NOAA-CO2-86
NOAA-CO2-87
NOAA-CO2-88
NOAA-CO2-89
NOPACCS-NH92
NOPACCS-NH95
COSMIC-NH97
COSMIC-NH98
WOCE-WHP-P02
WOCE–WHP-P04
WOCE-WHP-P09
WOCE-WHP-P16C
WOCE-WHP-P16S and 17S
WOCE-WHP-P17C
WOCE-WHP-P24
June 30–July 22, 1986
July 30–Aug. 28, 1987
Apr. 6–May 5, 1988
Feb. 15–May 20, 1989
Aug. 7–Oct. 5, 1992
Aug. 7–Oct. 5, 1995
Nov. 10, 1997–Jan. 19, 1998
Aug. 12–Oct. 21, 1998
Jan. 7–Feb. 10, 1994
Feb. 6–May 19, 1989
July 7–Aug. 25, 1994
Aug. 31–Oct. 1, 1991
July 16–Aug. 25, 1991
May 31–July 11, 1991
Nov. 15–Nov. 30, 1995
568N–158N, 1658W–1358W
508N–108N, 1658E–1298W
538N–108S, 1708W–1678W
148N–608S, 1308W–1058W
488N–128S, 1758E
488N–248N, 1508E–1758E
448N–108N, 1308E–1558E
448N–108N, 1408E–1558E
328N–308N, 1348E–1218W
108N–88N, 1278E–868W
338N–28S, 1378E–1428E
198N–188S, 1558W–1518W
68S–388S, 1518W–1358W
368N–68S, 1358W–1228W
318N–248N, 1328E–1378E
18
31
33
43
24
23
22
18
58
127
21
48
96
74
9
0–bottom
0–bottom
0–bottom
0–bottom
0–2000 m
0–bottom
0–bottom
0–bottom
0–bottom
0–bottom
0–bottom
0–bottom
0–bottom
0–bottom
0–2000 m
Wisegarver et al., 1993
Wisegarver et al., 1993
Wisegarver et al., 1993
Wisegarver et al., 1993
Watanabe et al., 1994
Watanabe et al., 1997
NEDO, 1998
NEDO, 1999
Watanabe et al., 1997
Toole et al., 1999
Kaneko, 1999
Tally, 1999a
Swift, 1999
Tsuchiya, 1999
Fujimura, 1999
Y.W. Watanabe et al.r Marine Chemistry 72 (2000) 297–315
Table 2
List of cruise information for CFC11 used in this study
305
306
Y.W. Watanabe et al.r Marine Chemistry 72 (2000) 297–315
is weak in the deep water, the period before 1950
may have a large contribution to HDC anthŽD t . d z. Thus,
great care needs to taken in the North Atlantic and
the Southern Oceans.
2.3.4. Biological effects
The next disadvantage of our approach is that it
shows only the rate of increase of anthropogenic
carbon due to the thermodynamic solubility effect.
The real ocean may be affected by changes in biological activity. This disadvantage is also a common
problem with all previous approaches and the direct
DIC comparison approach, andror the model calculations. Although there is still no evidence that the
oceanic biological activity responds to the change in
atmospheric anthropogenic carbon, it has been suggested that the oceanic biological impact is smaller
than the solubility effect ŽGruber et al., 1996..
2.3.5. Indirect estimation of anthropogenic carbon
Our approach gives an indirect estimate of the
rate of increase of the oceanic anthropogenic carbon
inventory by using mainly CFC11 age. Thus, we
must compare our estimate with other approaches
such as the direct DIC comparison approach. Ono et
al. Ž1998, 2000a. proposed to compare DIC directly
with an AOU correction on the same grid of 48
latitude= 108 longitude during a decadal time interval to estimate DC anthŽD t . . However, this direct DIC
comparison approach has the major limitation of the
insufficient quality of the historical data. To a lesser
extent, it is also limited by the insufficient spatial
distribution of the data available, even if limitation
of historical data can be partially overcome using
multiple regression techniques ŽSlansky et al., 1997..
Thus, we can apply our approach to the whole
North Pacific for obtaining the spatial distribution of
DC anthŽD t . , using the above equations and observational data summarized in Table 1. With consideration of the CFC11 dating error, we used here 10
years as the time interval of our approach to determine DC anthŽD t . in the Pacific. Practically, our estimation was carried out for the following three periods: 1968–1978, 1978–1988 and 1988–1998 AD.
Fig. 3. Locations of stations where CFC11 have been observed during the last decade in the Pacific. NOAA-CO2 -86 Ža. June–July 1986
ŽWisegarver et al., 1993., NOAA-CO2-87 Žb. July–August 1987 ŽWisegarver et al., 1993., NOAA-CO2 -88 Žc. April–May 1988,
NOAA-CO2-89 Žd. February–May 1989 ŽWisegarver et al., 1993., NOPACCS-NH92 Ž ) . August–October 1992 ŽWatanabe et al., 1994.,
NOPACCS-NH95 Ž`. August–October 1995 ŽWatanabe et al., 1997., COSMIC-NH97 Ž^. November 1997–January 1998 ŽNEDO, 1998.,
COSMIC-NH98 Žn. August–October 1998 ŽNEDO, 1999., WOCE-P02 Ža. January–February 1994 ŽWatanabe et al., 1997., WOCE-P04 Ži.
February–May 1989 ŽToole et al., 1999., WOCE-P09 Ž=. July–August 1994 ŽKaneko, 1999., WOCE-P16c and P16s Žy. August–October
1991 ŽSwift, 1999; Tally, 1999a., WOCE-P17c and P17s Žq. May–July 1991 ŽSwift, 1999; Tsuchiya, 1999. WOCE-P24 Žr. November
1995 ŽFujimura, 1999..
Y.W. Watanabe et al.r Marine Chemistry 72 (2000) 297–315
3. Data source and specific terms
To get t of water masses with S and T in the
Pacific, we used the open data sets CFC11 as shown
in Table 2 and Fig. 3. We also give the specific term,
equations and references that we used here for estimating the rate of increase of the oceanic anthropogenic carbon in Table 1.
4. Results and discussion
4.1. Comparison of DC a n t h( D t) between our approach
and the direct DIC comparison approach
Despite the difficulties associated with the direct
DIC comparison approach, Ono et al. Ž1998, 2000a,b.
determined average DC anthŽD t . in the western North
Pacific subtropical and subpolar regions using observed DIC data sets in the 1980s ŽChen et al., 1988.
and their recent DIC data sets. Thus, we here compared the vertical distribution of DC anthŽD t . between
our approach and the direct DIC comparison approach in the western North Pacific subtropical and
subpolar regions ŽFig. 4.. DC anthŽD t . decreases with
depth due to the atmospheric anthropogenic carbon
invasion with time. DC anthŽD t . near the surface around
25.0 su is about 0.9 mmol kgy1 yeary1 , and it is a
range from 0.5 to 0.1 mmol kgy1 yeary1 near 26.0
su –27.5 su , which agrees with the direct DIC comparison method’s results within the uncertainty of
our approach that discussed in Section 4.1.
4.2. Spatial distribution of DC a n t h( D t) in the North
Pacific
In the North Pacific, the isolines of DC anthŽD t .
generally deepens with time due to the influx of the
atmospheric anthropogenic carbon ŽFig. 5.. In deep
water, DC anthŽD t . decreases southward and eastward.
This distribution of DC anthŽD t . is mainly caused by
the behavior of the intermediate water represented as
a salinity minimum along about 26.8 su in the
North Pacific. The southward isopycnal flow of intermediate water is produced in the North Pacific
subpolar region and the upwelling occur in the tropical area ŽReid, 1965; Ostlund et al., 1979; Tally,
1988; Fine et al., 1981; VanScoy et al., 1991;
307
Watanabe et al., 1994; Warner et al., 1996; Tokieda
et al., 1996.. Thus, the subpolar region is an important area for the uptake of anthropogenic carbon into
the deeper water of the North Pacific.
On the other hand, in the shallow water, DC anthŽD t .
was more than 0.9 mmol kgy1 yeary1 in the subtropical region. It usually decreased northward and
eastward, due to the buffer factor of the oceanic
carbon content that enhances DC anthŽD t . with increase
in water temperature ŽRevelle and Suess, 1956;
Sundquist et al., 1979.. Warm northward water flows
such as the Kuroshio, mainly affect the distribution
of DC anthŽD t . in shallow waters. Thus, the Kuroshio
region is one of the important areas for the uptake of
anthropogenic carbon into the shallow water of the
North Pacific.
The area where the northward Kuroshio and the
southward intermediate flow meet, and these cause
the most effective increase rate of anthropogenic
carbon inventory, may be expected to be near the
western boundary between the tropical and subpolar
regions, 208N–408N. We found higher values of
DC anthŽD t . in both shallow and deep waters in the
western North Pacific subtropical region.
4.3. Spatial distributions of the rate of increase of
the anthropogenic carbon inÕentory in the North
Pacific
To clarify the extent of the rate of increase of the
anthropogenic carbon inventory in the entire water
column H CFC11s0.02r DC anthŽD t . d z in the North Pacific, the spatial distribution is shown in Fig. 6. The
same level of H CFC11s0.02r DC anthŽD t . d z generally
spreads with time due to the atmospheric anthropogenic carbon influx. An extensive minimum area
was found in the eastern equatorial area in all three
decades, and was still less than 3 g C my2 yeary1
during 1988–1998. On the other hand, a maximum
area of H CFC11s0.02r DC anthŽD t . d z of more than 8 g C
my2 yeary1 during the 1988–1998 decade, was
found in the Southern Ocean and the North Pacific
subtropical regions.
The spatial distributions of Hr DC anthŽD t . d z near
the surface layer and at intermediate depth are helpful to explain these minimum and maximum areas of
H CFC11s0.02r DC anthŽD t . d z ŽFig. 7.. Near the surface,
the maximum in the North Pacific subtropical region
308
Y.W. Watanabe et al.r Marine Chemistry 72 (2000) 297–315
Fig. 4. Comparison of the rate of increase of the oceanic anthropogenic carbon content between our approach and the direct DIC comparison
approach Žmmol kgy1 yeary1 ., DC anthŽD t . . ŽA. Average DC anthŽD t . in the western North Pacific subtropical region between 208N and 408N
during 1982–1983. ŽB. Average DC anthŽD t . in the western North Pacific subpolar region north of 408N during 1985–1999. The results of
direct DIC comparison approach are cited from Ono et al. Ž1998, 2000a,b..Their approach cannot estimate DC anthŽD t . near the surface layer
because of large variability of DIC and O 2 . Solid circles and open circles are, respectively, DC anthŽD t . estimated by our approach, and
DC anthŽD t . estimated by the direct DIC comparison approach. Each horizontal line associated with a solid circle is 0.12 mmol kgy1 yeary1
and it is the entire potential error of our approach. Horizontal lines with open circles are errors derived from the 5 mmol kgy1 as analytical
precision, 0.36–0.45 mmol kgy1 yeary1 Žs 5 mmol kgy1 r11 or 14 years., which is larger than the deviation derived from the spatial
distribution.
gradually spread to the whole North Pacific with
time, while large values of Hr DC anthŽD t . d z were not
found in both the eastern equatorial area and the
Southern Ocean ŽFig. 7a.. The distribution corresponded to the water temperature near the surface
layer. This suggests that warm water flows such as
the Kuroshio, which cause the buffer factor to decrease, mainly contribute to the maximum of
Hr DC anthŽD t . d z in the North Pacific. On the other
hand, cold water, which cases the buffer factor to
increase, mainly causes the distribution of lower
Hr DC anthŽD t . d z near the surface layer in both the
eastern equatorial area and the Southern Ocean.
Near the intermediate depth of the North Pacific,
Hr DC anthŽD t . d z increased with time and spread from
the subpolar region to the south while Hr DC anthŽD t . d z
in the eastern equatorial area was almost zero and
constant with time ŽFig. 7b.. On the other hand, in
the Southern Ocean, the maximum of 0.5 g C my2
yeary1 gradually spread northward with time. The
distribution corresponded to the behaviors of intermediate and deep waters: upwelling of deep water in
the eastern equatorial area, production and southward
transport of intermediate water in the North Pacific
subpolar region ŽReid, 1965; Ostlund et al., 1979;
Tally, 1988; Fine et al., 1981; VanScoy et al., 1991;
Y.W. Watanabe et al.r Marine Chemistry 72 (2000) 297–315
Fig. 5. Examples of the time and spatial distribution of the rate of increase of the anthropogenic carbon content in the Pacific Žmmol kgy1 yeary1 ., DC anthŽD t . . Upper and lower
panels show DC anthŽD t . along 1758E and 308N, respectively. These distributions were estimated during the following three intervals: 1968–1978, 1978–1988 and 1988–1998,
using the NOPACCS-NH92 ŽWatanabe et al., 1994. and WOCE-WHP-02 ŽWatanabe et al., 1994. data sets.
309
310
Y.W. Watanabe et al.r Marine Chemistry 72 (2000) 297–315
Fig. 6. Distributions of the rate of increase of the anthropogenic carbon inventory in the Pacific Žg C my2 yeary1 ., H CF C11s0.02r DC anthŽD t . d z.
Upper, middle and lower panels show H CF C11s0.02r DC anthŽD t . d z during 1968–1978, 1978–1988, and 1988–1998, respectively. The results
of H CF C11s0.02r DC anthŽD t . d z are smoothed using the Kernel’s procedure to obtain contours.
Y.W. Watanabe et al.r Marine Chemistry 72 (2000) 297–315
311
Fig. 7. Examples of distributions of the rate of increase of the anthropogenic carbon inventory between two isopycnal in the Pacific, Žg C
my2 yeary1 . and Hr DC anthŽD t . d z. Ža. 0 m–25.2 su , Žb. 26.8 su –27.0 su .
312
Y.W. Watanabe et al.r Marine Chemistry 72 (2000) 297–315
Watanabe et al., 1994; Warner et al., 1996; Tokieda
et al., 1996., and active production and northward
transport of intermediate and deep water in the
Southern Ocean ŽTsunogai, 1981; Jean-Baptiste et
al., 1991; Schlosser et al., 1991; Trumbore et al.,
1991.. These flows made the distribution of
H CFC11s0.02r DC anthŽD t . d z near the intermediate depth
of the Pacific. As a result of the combination of the
distributions of Hr DC anthŽD t . d z near the surface layer
and the intermediate-deep depth, minimum and maximum areas, H CFC11s0.02r DC anthŽD t . d z were found in
the Pacific ŽFig. 6.. In the North Pacific subtropical
region, the maximum is caused by both the Kuroshio
and the southward intermediate flow, which is examined in the Section 4.3.
4.4. Net total uptake rate of anthropogenic carbon in
the entire North Pacific
Furthermore, the integration of the above spatial
distribution of Hr DC anthŽD t . d z in the whole North
Pacific, allows the estimation of the total uptake rate
of anthropogenic carbon in the whole North Pacific,
or the net uptake rate of anthropogenic carbon.
We here averages H CFC11s0.02r DC anthŽD t . d z on a
grid of 108 latitude divided by 1908E, which is
approximately the center of the North Pacific, expressed as Ž H CFC11s0.02r DC anthŽD t . d z .ave . Multiplying
each Ž H CFC11s0.02r DC anthŽD t . d z .ave by its area Ž a.,
the uptake rate of anthropogenic carbon in each area
Ž D u anthŽD t . . was calculated. Furthermore, by integrat-
Fig. 8. The time change of the uptake rate of the anthropogenic carbon in each area of the North Pacific. Ža. Uptake rate of anthropogenic
C11s0.02 Ž .
carbon ŽPg C yeary1 ., D u CF
. b Averaged rate of increase of the anthropogenic carbon content in each area Žmmol ly1 yeary1 .,
anthŽD t .
DC anthŽD t .ave . Vertical lines with solid circles are a 90% confidence interval of the standard deviations derived from the spatial distribution.
Y.W. Watanabe et al.r Marine Chemistry 72 (2000) 297–315
ing D u anthŽD t . in the entire North Pacific, the total
uptake rate of anthropogenic carbon ŽÝŽ aD u anthŽD t . ..
was estimated.
The western subtropical region between 408N–
208N had the largest D u anthŽD t . in the North Pacific
ŽFig. 8.. The average value of DC anthŽD t . in the
western subtropical region was just between the value
in the tropical and subpolar regions. In addition, the
average depth of DC anthŽD t . in the western subtropical region was one of the deepest depths. This
suggests that the largest D u anthŽD t . in the western
subtropical region was caused by: Ž1. the encounter
of the Kuroshio and the southward intermediate flow
in this region; and Ž2. the convergence of water
masses with a strong clockwise surface flow causing
the warm isopycnal surface with larger DC anthŽD t . to
deepen. As a result, the western subtropical region
had a D u anthŽD t . of 0.18 Pg C yeary1 during 1988–
1998, and is an important area for the uptake of
anthropogenic carbon in the North Pacific.
In the entire North Pacific, ÝŽ aD u anthŽD t . . increased with time and was 0.31 " 0.05 Pg C yeary1
for 1968–1978, 0.42 " 0.07 Pg C yeary1 for 1978–
1988, and 0.55 " 0.09 Pg C yeary1 for 1988–1998
ŽFig. 9.. According to model calculations ŽSarmiento
et al., 1992; Siegenthaler and Joos, 1992; Maier-Reimer, 1993; Orr, 1993; Siegenthaler and Sarmiento,
1993; Stocker et al., 1994., the entire global oceanic
uptake of anthropogenic carbon was 2.0 " 0.8 Pg C
yeary1 on average Ž90% confidence interval. during
313
the 1980s. If one assumed that anthropogenic carbon
uptake had the same upward trend during the 1990s
as the atmospheric CO 2 increase, then it is expected
to be 2.3 Pg C yeary1 . Therefore, ÝŽ aD u anthŽD t . .
during 1988–1998 showed that the North Pacific
absorbed 24% of the whole recent oceanic uptake of
anthropogenic carbon.
5. Concluding remarks
We propose an approach to estimate the rate of
increase of the anthropogenic carbon content from
one decade to another and not the entire increase
from the pre-industrial period to the present. Using
this approach, we can draw the following conclusions for the oceanic uptake of anthropogenic carbon
in the North Pacific.
Ž1. The western subtropical region between
408N–208N had the largest Hr DC anthŽD t . d z in the
North Pacific. This was caused by both the encounter
of the Kuroshio and the southward intermediate flow
in this region, and the strong convergence of water
masses in this area. As a result, the western subtropical region in the North Pacific had an uptake rate of
anthropogenic carbon of 0.18 Pg C yeary1 during
the 1988–1998 decade. This is equivalent to 34% of
the total uptake rate in the entire North Pacific while
the western subtropical area is only 21% of total
area.
Ž2. In the entire North Pacific, ÝŽ aD u anthŽD t . .
increase with time and was 0.55 " 0.09 Pg C yeary1
during 1988–1998, suggesting that the North Pacific
absorbed 24% of the whole recent oceanic uptake of
anthropogenic carbon.
Acknowledgements
Fig. 9. The time change of the total uptake rate of the anthropogenic carbon in the whole North Pacific ŽPg C yeary1 .,
C11s0.02 .
ÝŽ aD u CF
. Vertical lines with solid circles indicate the
anthŽD t .
standard deviations derived from the spatial distributions.
We thank the scientists, officers and crew of
RrVs No. 1 Hakurei Maru, No. 2 Hakurei Maru and
Kaiyo Maru for their kind cooperation in the fieldwork. We also wish to thank Dr. H. Tsubota
ŽHiroshima University., Dr. M. Fukasawa ŽTokai
University., Mr. K. Ishida ŽKANSO. and Dr. I.
Kaneko ŽMRI. for sampling management and useful
314
Y.W. Watanabe et al.r Marine Chemistry 72 (2000) 297–315
advice on our approach. Finally, we also thank deeply
Dr. C.S. Wong ŽIOS. and the three reviewers who
gave us many useful comments.
References
Anderson, L.A., Sarmiento, J.L., 1994. Redfield ratios of remineralization determined by nutrient data analysis. Global Biogeochem. Cycles 10, 65–80.
Brewer, P.G., 1978. Direct observation of the oceanic carbon
dioxide increase. Geophys. Res. Lett. 5, 997–1000.
Chen, C.T.A., 1982. Oceanic penetration of excess CO 2 in a
cross-section between Alaska and Hawaii. Geophys. Res. Lett.
9, 117–119.
Chen, C.T.A., 1993. Anthropogenic CO 2 distribution in the North
Pacific Ocean. J. Oceanogr. 49, 257–270.
Chen, C.T.A., Millero, F.J., 1979. Gradual increase of oceanic
carbon dioxide. Nature 277, 205–206.
Chen, C.T.A., Pytkowicz, R.M., 1979. On the total carbon dioxide-titration alkalinity–oxygen system in the Pacific Ocean.
Nature 281, 362–365.
Chen, C.T.A., Rodman, M.R., Wei, C.L., Olson, E.J., Feely, R.A.,
Gendron, J.F., 1988. Carbonate Chemistry of the North Pacific
Ocean. NDP-029.
Dickson, A., Goyet, C., 1994. Handbook of Methods for the
Analysis of the Various Parameters of the Carbon Dioxide
System in Sea Water Version 2. DOE.
Doney, S.C., Bullister, J.L., 1992. A chlorofluorocarbon section in
the eastern North Atlantic. Deep-Sea Res. 39, 1857–1883.
Doney, S.C., Jenkins, W.J., Bullister, J.L., 1997. A comparison of
ocean tracer dating techniques on a meridional section in the
eastern North Atlantic. Deep-Sea Res. 44, 603–626.
Feely, R.A., Sabine, C.L., Key, R.M., Peng, T.H., Wanninkhof,
R., 1999. The U.S. global CO 2 survey in the North and South
Pacific Ocean: Preliminary synthesis results. Proceedings of
2nd International Symposium CO 2 in the Oceans, Tsukuba,
Japan. pp. 193–198.
Fine, R.A., Reid, J.L., Ostlund, H.G., 1981. Circulation of tritium
in the Pacific Ocean. J. Phys. Oceanogr. 11, 3–14.
Fujimura, M., 1999. World Ocean Circulation Experiment
ŽWOCE. hydrographic public data. Line P24. http:rrwhpo.
ucs.edurdataronetimerpacificrp09rindex.htm.
Goyet, C., Brewer, P.G., 1993. Biogeochemical properties of the
oceanic carbon cycle. In: Willebrand, J., Anderson, D.L.T.
ŽEds.., Modeling Oceanic Climate Interactions. Springer, New
York, pp. 271–297.
Goyet, C., Coatanoan, C., Eischeid, G., Amaoka, T., Okuda, K.,
Healy, R., Tsunogai, S., 1999. Spatial variation of total CO 2
and total alkalinity in the northern Indian Ocean: a novel
approach for the quantification of anthropogenic CO 2 in the
seawater. J. Mar. Res. 57, 135–163.
Gruber, N., 1998. Anthropogenic CO 2 in the Atlantic Ocean.
Global Biogeochem. Cycles 12, 165–191.
Gruber, N., Sarmiento, J.L., Stocker, T.F., 1996. An improved
method for detecting anthropogenic CO 2 in the oceans. Global
Biogeochem. Cycles 10, 809–837.
Jean-Baptiste, P., Mantisi, F., Memery, L., Jamous, D., 1991.
He-3 and chlorofluorocarbons in the southern ocean: tracers of
water masses. Mar. Chem. 35, 137–150.
Kaneko, I., 1999. World Ocean Circulation Experiment ŽWOCE.
hydrographic public data. Line P09. http:rrwhpo.ucsd.edur
dataronetimerpacificrp09rindex.htm.
Keeling, C.D., Whorf, T.P., 1999. Atmospheric CO 2 record from
Mauna Loa, 1958–1998. http:rrcdiac.esd.ornl.govrtrendsr
CO2rsio-mlo.htm.
Maier-Reimer, E., 1993. The biological pump in the greenhouse.
Global Biogeochem. Cycles 8, 13–15.
Millero, F.J., Lee, K., Roche, M., 1998. Distribution of alkalinity
in the surface waters of the major oceans. Mar. Chem. 60,
111–130.
NEDO, 1998. KANSO West-COSMIC Project Annual Report 1.
NEDO, 1999. KANSO West-COSMIC Project Annual Report 2.
NOAA, 1999. Halocarbon and Other Atmospheric Trace Species,
http:rrwww.cmdl.noaa.govrhatsrgraphsrgraphs.html.
Ono, T., Watanabe, S., Okuda, K., Fukasawa, M., 1998. Distribution of total carbonate and related properties in the North
Pacific along 30N. J. Geophys. Res. 103, 30873–30883.
Ono, T., Watanabe, Y.W., Watanabe, S., 2000a. Recent increase
of total carbonate in the western North Pacific. Mar. Chem. Žin
press..
Ono, T., Nakano, Y., Wakita, M., Watai, T., Fujimoto, T., Suzuki,
Y., Watanabe, Y.W., 2000b. Distribution of total carbonate
and related properties in the North Pacific along 47N measured in the late 1990s, in preparation.
Orr, J.C., 1993. Accord between ocean models predicting uptake
of anthropogenic CO 2 . Water, Air, Soil Pollut. 70, 643–657.
Ostlund, H.G., Brescher, R., Oleson, R., Feerguson, M.J., 1979.
GEOSECS Pacific radiocarbon and tritium results. Tritium
Laboratory Data Report 8, Univ. of Miami, Miami.
Peng, T.H., Wanninkhof, R., Bullister, J.L., Feely, R.A., Takahashi, T., 1998. Quantification of decadal anthropogenic CO 2
uptake in the ocean based on dissolved inorganic carbon
measurements. Nature 396, 560–563.
Quay, P.D., Tilbrook, B., Wong, C.S., 1992. Oceanic uptake of
fossil fuel CO 2 : C-13 evidence. Science 256, 74–79.
Reid, J.L., 1965. Intermediate waters of the Pacific Ocean, The
John Hopkins Oceanographic Study, vol. 2, 85 pp.
Revelle, R., Suess, H.E., 1956. Carbon dioxide exchange between
atmospheric and ocean and the question of an increase of
atmospheric during the past decades. Tellus 9, 18–27.
Sabine, C.L., Key, R.M., Goyet, C., Johnson, K.M., Millero, F.J.,
Poisson, A., Sarmiento, J.L., Wallace, D.W.R., Winn, C.D.,
1999a. Anthropogenic CO 2 inventory of the Indian Ocean.
Global Biogeochem. Cycles 13, 179–198.
Sabine, C.L., Key, R.M., Sarmiento, J.L., 1999b. Anthropogenic
carbon tracers and their use in evaluating global models.
Proceedings of 2nd International Symposium CO 2 in the
Oceans, Tsukuba, Japan. pp. 95–100.
Sarmiento, J.L., Orr, J.C., Siegenthaler, U., 1992. A perturbation
simulation of CO 2 uptake in an ocean general circulation
model. J. Geophys. Res. 97, 3621–3645.
Y.W. Watanabe et al.r Marine Chemistry 72 (2000) 297–315
Schlosser, P., Bullister, J.L., Bayer, R., 1991. Studies of deep
water formation and circulation in the Weddell Sea using
natural and anthropogenic tracers. Mar. Chem. 35, 97–122.
Siegenthaler, U., Joos, F., 1992. Use of a simple model for
studying oceanic tracer distributions and the global carbon
cycle. Tellus 44B, 186–207.
Siegenthaler, U., Sarmiento, J.L., 1993. Atmospheric carbon dioxide and the ocean. Nature 365, 119–125.
Shiller, A.M., 1981. Calculating the oceanic CO 2 increase: a need
for caution. J. Geophys. Res. 86, 11083–11088.
Shiller, A.M., 1982. Reply to comment by Chen et al., on
ACalculating the oceanic CO 2 increase: a need for cautionB by
A.M. Shiller. J. Geophys. Res. 87, 286.
Slansky, C.M., Feely, R.A., Wanninkhof, R., 1997. The stepwise
linear regression method for calculating anthropogenic CO 2
invasion into the North Pacific Ocean. Proceedings of International Marine Science Symposium on Biogeochemical Processes in the North Pacific, Japan, Japan Marine Science. pp.
70–79.
Stocker, T.F., Broecker, W.S., Wright, D.G., 1994. Carbon uptake
experiments with a zonally-averaged global ocean circulation
model. Tellus 46B, 103–122.
Sundquist, E.T., Plummer, L.N., Wigley, T.M.L., 1979. Carbon
dioxide in the ocean surface: the homogeneous buffer factor.
Science 204, 1203–1205.
Swift, J.H., 1999. World Ocean Circulation Experiment ŽWOCE.
hydrographic public data, Line P16s & 17s. http:rrwhpo.
ucsd.edurdataronetimerpacificrp16rp16srindex.htm.
Tally, L.D., 1988. Potential vorticity distribution in the North
Pacific. J. Phys. Oceanogr. 18, 89–106.
Tally, L., 1999. World Ocean Circulation Experiment ŽWOCE.
hydrographic public data, Line P16c. http:rrwhpo.ucsd.edur
dataronetimerpacificrp16rp16crindex.htm.
Tokieda, T., Watanabe, S., Tsugonai, S., 1996. Chlorofluorocarbons in the western North Pacific in 1993 and formation of
North Intermediate Water. J. Oceanogr. 52, 478–490.
Toole, J., Brady, E., Bryden, E., 1999. World Ocean Circulation
Experiment ŽWOCE. hydrographic public data, Line P04.
http:rrwhpo.ucsd.edu r data r onetime rpacific rp04 rindex.
htm.
Trumbore, S.E., Jacobs, S.S., Smethie, W.M. Jr., 1991. Chlorofluorocarbon evidence for rapid ventilation of the Ross Sea.
Deep-Sea Res. 38, 845–870.
315
Tsuchiya, M., 1999. World Ocean Circulation Experiment
ŽWOCE. hydrographic public data, Line P17c. http:rrwhpo.
ucsd.edurdataronetimerpacificrp17rp17crindex.htm.
Tsunogai, S., 1981. A method for chronology of the Pacific and
Atlantic deep water and its application. Chikyu Kagaku ŽGeochemistry. 15, 70–76.
Tsunogai, S., Ono, T., Watanabe, S., 1993. Increase in total
carbonate in the Western North pacific water and a hypothesis
on the missing sink of anthropogenic carbon. J. Oceanogr. 49,
305–315.
Uppstrom, L.R., 1974. The boronrchlorinity ratio of deep-sea
water from the Pacific Ocean. Deep-Sea Res. 21, 161–162.
VanScoy, K.A., Fine, R.A., Ostlund, H.G., 1991. Two decades of
mixing tritium into the North Pacific Ocean. Deep-Sea Res.
38, 191–219.
Wallace, D.W.R., Johnson, K.M., 1994. Prediction of total dissolved inorganic carbon on basin scales by simple multiple
liner regression. EOS Trans. AGU 75, 160.
Warner, M.J., Weiss, R.F., 1985. Solubilities of chlorofluorocarbons 11 and 12 in water and seawater. Deep-Sea Res. 32,
1485–1497.
Warner, M.J., Bullister, J.L., Wisegarver, D.P., Gammon, R.H.,
Weiss, R.F., 1996. Basin-wide distribution of chlorofluorocarbons CFC-11 and CFC-12 in the North Pacific: 1985–1989. J.
Geophys. Res. 101, 20525–20542.
Watanabe, Y.W., Harada, K., Ishikawa, K., 1994. Chlorofluorocarbons in the Central North Pacific and southward spreading
time of North Pacific intermediate water. J. Geophys. Res. 99,
25195–25213.
Watanabe, Y.W., Ishida, A., Tamaki, M., Okuda, K., Fukasawa,
M., 1997. Water column inventories of CFCs and production
rate of intermediate water in the North Pacific. Deep-Sea Res.
44, 1091–1104.
Watanabe, Y.W., Shimamoto, A., Kitada, M., 1999. Background
levels of SF6 , CFC11, CFC12 and CFC13 in the western North
Pacific. Proceeding of the 1999 Spring Meeting of the
Oceanographic Society of Japan, Tokyo, Japan.
Weiss, R.F., 1974. Carbon dioxide in water and seawater: the
solubility of a non-ideal gas. Mar. Chem. 2, 203–215.
Wisegarver, D.P., Bullister, J.L., Gammon, R.H., Menzia, F.A.,
Kelly, K.C., 1993. NOAA chlorofluorocarbon tracer program
— air and measurements: 1986–1989. NOAA Data Report
ERL PMEL 43.