We report the interannual variations of winter CO₂ partial pressure in surface waters (pCO₂^sea) and overlying air (pCO₂^air) and air-sea CO₂ flux in the extensive area (3-34°N) from subtropical to equatorial along 137°E during the period of 1983-2003. The pCO₂^sea varied largely in the equatorial region of 3-6°N, depending on the variations of the oceanographic conditions related to the El Niño-Southern Oscillation (ENSO) events. The pCO₂^sea variations in the subtropical gyre north of 23°N were small due to highly counteracting effects between anti-correlated sea surface temperature (SST) and dissolved inorganic carbon (DIC) anomalies through the entrainment process, irrespective of large variations of SST. By contrast, it was found that there occurred a low negative correlation between SST and DIC in the region restricted around 15-18°N in the North Equatorial Current, which resulted in a large amplitude of variations of pCO₂^sea and hence CO₂ influx. The interannual variations of CO₂ flux depended predominantly on those of the difference between pCO₂^sea and pCO₂^air (ΔpCO₂) south of 18°N but on those of wind speed in the northern region. 

We present a 30+ year record of continuous atmospheric CO₂ concentrations and a 5 year record of continuous O₂ concentrations from Baring Head, New Zealand. When compared to South Pole data, the CO₂ concentrations indicate a persistent, but variable net carbon sink in the Southern Ocean since the late 1970s. The amplitude of the seasonal cycle of O₂ concentrations (expressed as “APO”, Atmospheric Potential Oxygen) shows large inter-annual variability, suggesting high variability in annual air-sea O₂ fluxes, and thus also potentially suggesting high variability in year to year marine productivity in the Southern Ocean.

We apply to Classical Labrador Sea Water (CLSW) the “transit-time distribution” (TTD) method to estimate the inventory and uptake anthropogenic carbon (∆C). A parametric model of TTDs representing bulk-advective and mixing processes is constrained with WOCE CFC data. The constrained TTDs are then used to propagate ∆C into the interior of the CLSW. Compared to many past studies the key advantage of this methodology is that mixing is not assumed to be a negligible component of transport.

An accurate knowledge of the thermodynamics of the carbonic acid system in seawater is crucial to our understanding of the behavior of carbon dioxide in seawater. In particular, this knowledge is needed whenever a particular property needs to be calculated from measurements of other related properties; e.g., the estimation of the partial pressure of CO2 in air that is in equilibrium with a sample of sea water, p(CO2), from measurements of the total dissolved inorganic carbon, CT, and of the total alkalinity, AT, of a water sample. This calculation is particularly important for ocean models, which transport CT and AT, but which need to calculate p(CO2) at the sea surface so as to represent air-sea exchange processes. Numerous determinations of dissociation constants for carbon dioxide in seawater media have been published over the years. In each case the authors have recommended “best” values for the dissociation constants, and often the constants are represented in these papers by interpolating equations or tables. Furthermore, a number of investigators have attempted to assess the thermodynamic consistency of the various published values for these dissociation constants with analytical measurements made on natural seawater. Despite all this work, the results of these efforts are, as yet, not conclusive. I shall present a review of the situation and will try to provide a clear description of the magnitude of the problems, their possible sources, and their importance to understanding the behavior of CO2 in seawater.

We analysed the temporal variations of the CO₂ system in the Southern Ocean south of Tasmania and compared the seasonality of the carbon dioxide fugacity (fCO₂) and the air-sea CO₂ flux during spring and summer for two different years: 1996/97 and 2002/03. In summer, the CO₂ flux presents large and contrasting interannual changes in the Permanent Open Ocean Zone (POOZ, 53-61°S): the oceanic CO₂ sink varies from about –0.3 mmol.m^-2.d^-1 in 1997 to –20.6 mmol.m^-2.d^-1 in 2003. This strong sink in February 2003 was related to an increased phytoplankton biomass in this high-nutrient, low-chlorophyll (HNLC) region.

We have conducted long-term regular monitoring of vertical profiles of ¹³C/¹²C ratio of atmospheric CO₂ over three sites in Siberia and a site in Japan. Time-series and seasonality of the ¹³C/¹²C ratio at each altitude levels at the four site were examined. Apparent isotopic signature was calculated from the relationship between CO₂ mixing ratio and the ¹³C/¹²C ratio in individual vertical profiles.

Begur-Pals site (41,58ºN, 3,14ºE, Catalonia, Spain) is weekly sampled for CO₂ and other GHG (CH₄, CO, N₂O, SF₆) since January 2000. This CO₂ serial data shows at the middle of each summer a sudden increase and decrease of the CO₂ peak. It is a process that can be either attributed to a highest transpiration rate than ecosystem production due to the lack of summer precipitation, to biomass burning from Mediterranean forest fires, to tourist activities in the coast, or to CO₂ pumping from waters in the Western Mediterranean sea (according to wind backtrajectories). A sampling strategy using sites with high towers with continuous measurements has been developed. Sites are placed at the vortexes of a rhombus: two extremes are continental sites in the center of the Ebro’s watershed and a marine site is located in the Menorca Island. The other two are high towers in the Catalonian coast.

Anthropogenic CO₂ releases to the atmosphere have changed the total inorganic carbon concentration of ocean by no more than 3-4% at any location. Main differences between three approaches [Poisson and Chen, 1987; Gruber et al., 1996; Friis, 2005] are presented that define marine anthropogenic CO₂ (C_T^ant) as deduced from total inorganic carbon. All definitions are based on a back-calculation technique that was independently proposed by Brewer [1978] and Chen and Millero [1979]. The overall importance of this presentation is in the comparability of anthropogenic CO₂ findings from described methods with these derived from global bookkeeping approaches or full carbon model results.

Upwelling of high-nutrient waters in the equatorial Pacific gives rise to a band of enhanced primary production around the equator that stretches from Peru almost to Indonesia. It has been suggested that this oceanic region accounts for a large part of global net production. The equatorial Pacific is also thought to be the largest oceanic CO₂ source and makes an important contribution to the atmospheric CO₂ budget.