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1.
The multiple-parameter linear regression method (Monitoring global ocean carbon inventories. Ocean Observing System Development Panel, Texas A&M University, College Station, TX, 1995, 54pp; Global Biogeochem. Cycles 13 (1999) 179) is used to compare inorganic carbon data from the GEOSECS CO2 survey in the Pacific Ocean in 1973 to the WOCE/JGOFS global CO2 survey in the 1990s. A model of total dissolved inorganic carbon (DIC) as a function of five variables (AOU, θ, S, Si, and PO4) has been developed from the recent CO2 survey data (namely CGC91 and CGC96) in the Pacific Ocean. After correcting for a systematic DIC offset of −30.3±7 μmol kg−1 from the GEOSECS data, the residual DIC based on this model as computed from GEOSECS data has been used to estimate the anthropogenic CO2 penetration in the Pacific Ocean. In the Northeast Pacific, we obtained an increase of CO2 of 21.3±7.9 mol m−2 over the period from GEOSECS in 1973 to CGC91 in 1991. This gives a mean anthropogenic CO2 uptake rate of 1.3±0.5 mol m−2 yr−1 over this 17 year time period. In the South Pacific, north of 50°S between 180° and 120°W region, the integrated anthropogenic CO2 inventory is estimated to be 19.7±5.7 mol m−2 over the period from GEOSECS in 1974 to CGC96 in 1996. The equivalent mean CO2 uptake rate is estimated to be 0.9±0.3 mol m−2 yr−1 over the 22 years. These results are compared with the isopycnal method (Nature 396 (1998) 560) to estimate the anthropogenic CO2 signal in the Northeast Pacific (30°N, 152°W) at the crossover region between CGC91 and GEOSECS. The results of the isopycnal method are consistent with those derived from the MLR method. Both methods show an increase in anthropogenic CO2 inventory in the ocean over two decades that is consistent with the increase expected if the ocean uptake has kept pace with the atmospheric CO2 increase.  相似文献   

2.
Sea water samples were collected from various depths in the North Pacific (40–21°N) along 165°E in 1991. Their total carbonate (total dissolved carbonate species) contents were determined with random errors less than 0.2% by a coulometric method. The preformed carbonate contents defined by Chen (1982) were calculated from the obtained data and other observed data including potential temperature, salinity, dissolved oxygen and total alkalinity. The same calculation was done for the GEOSECS data obtained in nearly the same region in 1973. The difference between the two data sets reveals that the preformed carbonate has increased by 180±41 gC/m2 during the last 18 years. This value is comparable or somewhat larger than 150 gC/m2 obtained in the case that the ocean uptakes 3 GtC/yr for 18 years and distributes it equally among the world oceans. Based on the results, a hypothesis on the missing sink for the anthropogenic carbon dioxide is presented, in that the missing sink is the intermediate waters formed in the northern North Pacific and the Southern Ocean besides the deep waters formed in the North Atlantic and the Southern Ocean.  相似文献   

3.
Radiocarbon and total carbonate data were obtained near the 1973 GEOSECS stations in the North Pacific along 30°N and along 175°E between 1993 and 1994. In these stations, we estimated radiocarbon originating from atomic bomb tests using tritium, trichlorofluoromethane and silicate contents. The average penetration depth of bomb radiocarbon during the two decades has deepened from 900 m to 1300 m. Bomb radiocarbon inventories above the average value for the whole North Pacific were found widely in the western subtropical region around 30°N both in the 1970s and 1990s, and its area in the 1990s was broader than that in the 1970s. In most of the North Pacific, while the bomb radiocarbon has decreased above 25.4, the bomb radiocarbon flux below 25.4 was over 1 × 1012 atom m-2yr-1 in the subtropical region around 30°N. In the tropical area south of 20°N, the bomb radiocarbon inventory below 25.4 increased from zero to over 10 × 1012 atom m-2 during the last three decades. These distributions suggest that the bomb radiocarbon removed from the surface is currently accumulated with bomb 14C flux of over 1 × 1012 atom m-2yr-1 below 25.4 in the subtropical region, mainly by advection from the higher latitude, and that part of the accumulated bomb 14C gradually spread southward with about 30 years.  相似文献   

4.
Particulate matter was collected in the Bering Sea and the northern North Pacific Ocean during the cruise of R. V. Hakuho-maru, Ocean Research Institute of Tokyo University in summer of 1975. The particulate matter was analyzed for organic carbon and nitrogen, chlorophylla and amino acids.The concentrations of particulate organic carbon and nitrogen were measured with the range of 16–422gC l–1 and 1–85gN l–1, 19–186gC l–1 and 1–26gN l–1, 46–1,038gC l–1 and 6–79gN l–1 and 19–246gC l–1 and 2–25gN l–1 in the Oyashio, the Deep Bering Sea, the continental shelf of Bering Sea and the northern North Pacific, respectively. Particulate organic carbon and nitrogen decreased with depth throughout the areas. The average concentrations of organic carbon and nitrogen in the entire water column tended to decrease in the following order; the continental shelf > Oyashio > northern North Pacific > Deep Bering Sea.C/N of particulate matter varied in the range of 3–15 (7 on average) in surface waters throughout the areas and these values tended to increase with depth to 5–20 (11 on average) in deep waters without significant regional variability.Linear regressions between chlorophylla and particulate organic carbon in the euphotic layers indicate that detrital organic carbon accounted for 34.2, 44.9, 49.1 and 25.2 % of particulate organic carbon in the Oyashio, the Deep Bering Sea, the continental shelf and the northern North Pacific, respectively.Particulate amino acid was determined in the range of 10.3–78.0g l–1, 104–156g l–1 and 10.4–96.4g l–1 in the Deep Bering Sea, the continental shelf and the northern North Pacific, respectively. Aspartic acid, glutamic acid, serine, glycine and alanine were found as dominant species of amino acid of particulate matter.  相似文献   

5.
Time-series measurements of dissolved inorganic carbon (DIC) and nutrient concentrations were conducted in the northwestern North Pacific from October 2002 to August 2004. Assuming that data obtained in different years represented time-series seasonal data for a single year, vertical distributions of DIC and nutrients showed large seasonal variabilities in the surface layer (∼100 m). Seasonal variabilities in normalized DIC (nDIC) and nitrate concentrations at the sea surface were estimated to be 81–113 μmol kg−1 and 12.7–15.7 μmol kg−1, respectively, in the Western Subarctic Gyre. The variability in nutrients between May and July was generally at least double that in other seasons. In the Western Subarctic Gyre, estimations based on statistical analyses revealed that seasonal new production was 39–61 gC m−2 and tended to be higher in the southwestern regions or coastal regions. The seasonal new productions in the northwestern North Pacific were two or more times higher than in the North Pacific subtropical gyre and the northeastern North Pacific. It is likely that this difference is due to spatial variations in the concentrations of trace metals and the species of phytoplankton present. In addition, from estimations of surface pCO2 it was verified that the Western Subarctic Gyre is a source of atmospheric CO2 between February and May and a sink for CO2 between July and October.  相似文献   

6.
Nitrogen isotope compositions of particulate organic matter and nitrate were analyzed for seawater sampled at five stations at the Alaskan Gyre, Western Subarctic Gyre and East China Sea, focusing on the samples from the surface to 5000 m water to characterize the nitrogen cycling in the subarctic North Pacific Ocean and its marginal sea. The 15N of particulate organic matter showed little agreement with a conceptual closed model that interprets isotopic variation as being caused by isotope discrimination on nitrate utilization. The 15N and 13C of particulate organic matter varied with the water depth. A correlation between isotope compositions and C/N elemental ratio was found generally at all stations, although some irregular data were also found in deep layers. We developed a hypothetical nitrogen balance model based on N2 fixation and denitrification in seawater and attempted to apply it to distinguish nutrient cycling using both 15N-NO3 – and N* variation in seawater. This model was applied to the observed data set of 15N-NO3 – and N* in the North Pacific water and estimated the 15N-NO3 – of primordial nitrate in the North Pacific deep water as 4.8. The North Pacific intermediate water for all stations showed similar 15N-NO3 – and N* values of 6 and –3 µmol/kg, respectively, suggesting a similar nitrogen biogeochemistry. In the East China Sea, analysis showed evidence of water exchange with the North Pacific intermediate water but a significant influence of nitrogen from the river runoff was found in depths shallower than 400 m.  相似文献   

7.
Primary productivity was measured byin situ method using13C in the offshore Oyashio region in the spring (May) and summer (September) of 1990. Most of the values were within the range of 0.1 to 4 gC 1–1 h–1 although a very large value, 7.96 gC l–1 h–1, was observed in summer. Most daily primary production fell within the range of 372 to 633 mgC m–2 d–1 although a very large value, 2,109 mgC m–2 d–1, was observed around the frontal area in summer. Chlorophylla (Chl.a) exceeded 1 g l–1 in many cases, and the maximum was 4.61 g l–1 in spring and 7.53 g l–1 in summer. Most primary productivity per unit Chl.a (photosynthetic assimilation ratio) was within the range of 0.1 to 3 gC gChl.a –1 h–1 although higher values, 3–6 gC gChl.a –1 h–1, were observed where small-size phytoplanktons (<2 m) were dominant. These results were compared with results obtained until now in the Oyashio region. The values beyond the range obtained so far in the offshore region were also observed in this study. Furthermore, it was pointed out that the size composition of phytoplankton community has significant influence on the results of Chl.a and photosynthetic assimilation ratio in the Oyashio region.  相似文献   

8.
Hydrographic measurements by CTD were made in the western-central Equatorial Pacific (160°W–147°E) during the Japanese Pacific Climate Study cruise in January–February 1991. InT-S diagram, three water masses are seen in the layer of kg/m3: salinity water corresponding to the Tropical Water of eastern South Pacific origin, less saline water in the North Pacific, and water with salinity between the above two, found on the equator. In three meridional sections (160°W–160°E), the Tropical Water of eastern South Pacific origin extends further equatorward than the climatological data of Levitus (1982).  相似文献   

9.
Excess CO2 and pHexcess showing an increase in dissolved inorganic carbon and a decrease in pH from the beginning of the industrial epoch (middle of the 19th century) until the present time have been calculated in the intermediate water layer of the northwestern Pacific and the Okhotsk Sea. It is concluded that: (1) The Kuril Basin (Okhotsk Sea) and the Bussol' Strait areas are characterized by the greatest concentrations of excess CO2 at isopycnal surfaces due to the processes of formation and transformation of intermediate water mass. (2) The largest difference in excess CO2 concentration between the Okhotsk Sea and the western subarctic Pacific (about 8 µmol/kg) is found at the = 27.0. (3) The difference in excess CO2 between the western subarctic Pacific and subtropical regions is significant only in the upper part of the intermediate water layer ( = 26.7–27.0). (4) About 10% of the excess CO2 accumulation in the subtropical north Pacific is determined by water exchange with the subarctic Pacific and the Okhotsk Sea.  相似文献   

10.
The uptake of atmospheric carbon dioxide in the water transported over the Bering–Chukchi shelves has been assessed from the change in carbon-related chemical constituents. The calculated uptake of atmospheric CO2 from the time that the water enters the Bering Sea shelf until it reaches the northern Chukchi Sea shelf slope (1 year) was estimated to be 86±22 g C m−2 in the upper 100 m. Combining the average uptake per m3 with a volume flow of 0.83×106 m3 s−1 through the Bering Strait yields a flux of 22×1012 g C year−1. We have also estimated the relative contribution from cooling, biology, freshening, CaCO3 dissolution, and denitrification for the modification of the seawater pCO2 over the shelf. The latter three had negligible impact on pCO2 compared to biology and cooling. Biology was found to be almost twice as important as cooling for lowering the pCO2 in the water on the Bering–Chukchi shelves. Those results were compared with earlier surveys made in the Barents Sea, where the uptake of atmospheric CO2 was about half that estimated in the Bering–Chukchi Seas. Cooling and biology were of nearly equal significance in the Barents Sea in driving the flux of CO2 into the ocean. The differences between the two regions are discussed. The loss of inorganic carbon due to primary production was estimated from the change in phosphate concentration in the water column. A larger loss of nitrate relative to phosphate compared to the classical ΔN/ΔP ratio of 16 was found. This excess loss was about 30% of the initial nitrate concentration and could possibly be explained by denitrification in the sediment of the Bering and Chukchi Seas.  相似文献   

11.
Concentrations and inventories of137Cs and239,240Pu were determined in sea waters and sediments columns from the western North Pacific from 1980 to 1986.The239,240Pu/137Cs activity ratio in the water column shows a tendency to increase from the surface (10–3) to bottom waters (10–1), but the ratio in sediment is within a rather narrow range (10–2 to 10–1), indicating more effective removal of plutonium from the water column than137Cs. In regions south of 40N, the radionuclide inventories in the water column significantly exceed the estimated global fallout (stratospheric fallout due to the atmospheric nuclear explosion), especially in the case of239,240Pu. These excess inventories imply that local or close-in fallout derived from nuclear explosions in the equatorial North Pacific are well-preserved and retained in the regions, despite about 20 years since the atmospheric nuclear explosion moratorium. Data suggesting lateral transport of137Cs in surface water from north of 40N to southern regions is shown. Some data on90Sr contents are also shown.  相似文献   

12.
More than 14,000 measurements of surface water xCO2 were obtained during two cruises, 3 weeks apart in June 2000, along 155°E between 34 and 44°N in the western North Pacific Ocean. Based on the distributions of salinity and sea surface temperature (SST), the region has been divided into 6 subregions; Oyashio, Oyashio front, Transition, Kuroshio front, and Kuroshio extension I and II zones, from north to south. The surface waters were always undersaturated with respect to atmospheric CO2. The Oyashio water was the least undersaturated: its xCO2 decreased slightly by 7 ppm, while SST increased by 2°C. The xCO2 normalized to a constant temperature decreased considerably. In the two frontal zones, a large drawdown of 30–40 ppm was observed after 18–19 days. In the Kuroshio extension zones, the xCO2 increased, but the normalized xCO2 decreased considerably. The Transition zone water may be somewhat affected by mixing with the subsurface water, as indicated by the smallest SST rise, an undecreased PO4 concentration, and a colder and less stable surface layer than the Oyashio front water. As the uncertainty derived from the air-sea CO2 flux was not large, the xCO2 data allowed us to calculate the net biological productivity. The productivities around 60 mmol C m−2d−1 outside the Transition zone indicate that the northwestern North Pacific, especially the two frontal zones, can be regarded as one of the most productive oceans in the world.  相似文献   

13.
We report several biogeochemical parameters (dissolved inorganic carbon (DIC), total alkalinity (TA), dissolved oxygen (DO), phosphate (PO4), nitrate + nitrite (NO3 + NO2), silicate (Si(OH)4)) in a region off Otaru coast in Hokkaido, Japan on a “weekly” basis during the period of April 2002–May 2003. To better understand the long-term temporal variations of the main factors affecting CO2 flux in this coastal region and its role as a sink/source of atmospheric CO2, we constructed an algorithm of DIC and TA using other hydrographic properties. We estimated the CO2 flux across the air–sea interface by using the classical bulk method. During 1998–2003 in our study region, the estimated fCO2sea ranged about 185–335 μatm. The maximum of fCO2sea in the summer was primarily due to the change of water temperature. The minimum of fCO2sea in the early spring can be explained not only by the change of water temperature but also the change of nutrients and chlorophyll-a. To clarify the factors affecting fCO2sea (water temperature, salinity, and biological activity), we carried out a sensitivity analysis of these effects on the variation of fCO2sea. In spring, the biological effect had the largest effect for the minimum of fCO2sea (40%). In summer, the water temperature effect had the largest effect for the maximum of fCO2sea (25%). In fall, the water temperature effect had the largest effect for the minimum of fCO2sea (53%). In winter, the biological effect had the largest effect for the minimum of fCO2sea (35%).We found that our study region was a sink region of CO2 throughout a year (−0.78 mol/m2/yr). Furthermore, we estimated that the increase of fCO2sea was about 0.56 μatm/yr under equilibrium with the atmospheric CO2 content for the period 1998–2003, with the temporal changes in the variables (T, S, PO4) on fCO2sea, thus as the maximum trend of each variable on fCO2sea was 0.22 μatm/yr, and the trend of residual fCO2 including gas exchange was 0.34 μatm/yr. This result suggests that interaction among variables would affect gas exchange between air and sea effects on fCO2sea. We conclude that this study region as a representative coastal region of marginal seas of the North Pacific is special because it was measured, but there is no particular significance in comparison to any other area.  相似文献   

14.
Comprehensive sea surface surveys of the partial pressure of carbon dioxide (pCO2) have been made in the upwelling system of the coastal (0–200 km from shore) southeastern tropical Pacific since 2004. The shipboard data have been supplemented by mooring and drifter based observations. Air–sea flux estimates were made by combining satellite derived wind fields with the direct sea surface pCO2 measurements. While there was considerable spatial heterogeneity, there was a significant flux of CO2 from the ocean to the atmosphere during all survey periods in the region between 4° and 20° south latitude. During periods of strong upwelling the average flux out of the ocean exceeded 10 moles of CO2 per square meter per year. During periods of weaker upwelling and high productivity the CO2 evasion rate was near 2.5 mol/m2/yr. The average annual fluxes exceed 5 mol/m2/yr. These findings are in sharp contrast to results obtained in mid-latitude upwelling systems along the west coast of North America where the average air–sea CO2 flux is low and can often be from the atmosphere into the ocean. In the Peruvian upwelling system there are several likely factors that contribute to sea surface pCO2 levels that are well above those of the atmosphere in spite of elevated primary productivity: (1) the upwelling source waters contain little pre-formed nitrate and are affected by denitrification, (2) iron limitation of primary production enhanced by offshore upwelling driven by the curl of the wind stress and (3) rapid sea surface warming. The combined carbon, nutrient and oxygen dynamics of this region make it a candidate site for studies of global change.  相似文献   

15.
The dissolved inorganic carbon (DIC) and related chemical species have been measured from 1992 to 2001 at Station KNOT (44°N, 155°E) in the western North Pacific subpolar region. DIC (1.3∼2.3 µ mol/kg/yr) and apparent oxygen utilization (AOU, 0.7∼1.8 µmol/kg/yr) have increased while total alkalinity remained constant in the intermediate water (26.9∼27.3σθ). The increases of DIC in the upper intermediate water (26.9∼27.1σθ) were higher than those in the lower one (27.2∼ 27.3σθ). The temporal change of DIC would be controlled by the increase of anthropogenic CO2, the decomposition of organic matter and the non-anthropogenic CO2 absorbed at the region of intermediate water formation. We estimated the increase of anthropogenic CO2 to be only 0.5∼0.7 µmol/kg/yr under equilibrium with the atmospheric CO2 content. The effect of decomposition was estimated to be 0.8 ± 0.7 µmol/kg/yr from AOU increase. The remainder of non-anthropogenic CO2 had increased by 0.6 ± 1.1 µmol/kg/yr. We suggest that the non-anthropogenic CO2 increase is controlled by the accumulation of CO2 liberated back to atmosphere at the region of intermediate water formation due to the decrease of difference between DIC in the winter mixed layer and DIC under equilibrium with the atmospheric CO2 content, and the reduction of diapycnal vertical water exchange between mixed layer and pycnocline waters. In future, more accurate and longer time series data will be required to confirm our results.  相似文献   

16.
Assessment was made of residual ratio of North Pacific Intermediate Water (NPIW) produced in subpolar region of the North Pacific using chlorofluorocarbons, CFC-11 and CFC-12 (CCl3F and CCl2F2), along 175°E. NPIW on density horizons less than 26.80 remained more than 80% north of 30°N. It was suggested that new NPIW laterally spreads over the northern North Pacific without hardly being diluted by the surroundings. For density horizons greater than 26.80 north of 30°N, NPIW remained less than 60%. The difference in the residual ratio between <26.80 and >26.80 north of 30°N suggests that NPIW is produced on density horizons less than 26.80, which contacts the atmosphere in the subpolar region, and that NPIW is diluted by upwelling deep water on density horizons greater than 26.80 in high latitude of the North Pacific. NPIW on a density horizon of 26.80 remained about 50% south of 30°N. The decrease in the horizontal distribution of the residual ratio of NPIW suggests that half the new NPIW produced in the subpolar region is laterally spread over the North Pacific with the southward movement of NPIW.  相似文献   

17.
Most marginal seas in the North Pacific are fed by nutrients supported mainly by upwelling and many are undersaturated with respect to atmospheric CO2 in the surface water mainly as a result of the biological pump and winter cooling. These seas absorb CO2 at an average rate of 1.1 ± 0.3 mol C m−2yr−1 but release N2/N2O at an average rate of 0.07 ± 0.03 mol N m−2yr−1. Most of primary production, however, is regenerated on the shelves, and only less than 15% is transported to the open oceans as dissolved and particulate organic carbon (POC) with a small amount of POC deposited in the sediments. It is estimated that seawater in the marginal seas in the North Pacific alone may have taken up 1.6 ± 0.3 Gt (1015 g) of excess carbon, including 0.21 ± 0.05 Gt for the Bering Sea, 0.18 ± 0.08 Gt for the Okhotsk Sea; 0.31 ± 0.05 Gt for the Japan/East Sea; 0.07 ± 0.02 Gt for the East China and Yellow Seas; 0.80 ± 0.15 Gt for the South China Sea; and 0.015 ± 0.005 Gt for the Gulf of California. More importantly, high latitude marginal seas such as the Bering and Okhotsk Seas may act as conveyer belts in exporting 0.1 ± 0.08 Gt C anthropogenic, excess CO2 into the North Pacific Intermediate Water per year. The upward migration of calcite and aragonite saturation horizons due to the penetration of excess CO2 may also make the shelf deposits on the Bering and Okhotsk Seas more susceptible to dissolution, which would then neutralize excess CO2 in the near future. Further, because most nutrients come from upwelling, increased water consumption on land and damming of major rivers may reduce freshwater output and the buoyancy effect on the shelves. As a result, upwelling, nutrient input and biological productivity may all be reduced in the future. As a final note, the Japan/East Sea has started to show responses to global warming. Warmer surface layer has reduced upwelling of nutrient-rich subsurface water, resulting in a decline of spring phytoplankton biomass. Less bottom water formation because of less winter cooling may lead to the disappearance of the bottom water as early as 2040. Or else, an anoxic condition may form as early as 2200 AD. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

18.
Grazing experiments and production estimation based on life-history analysis of Neocalanus copepods (N. cristatus, N. plumchrus and N. flemingeri) were carried out in the Oyashio region to understand the carbon flows associated with the interzonal migrating copepods. These copepods, and also Eucalanus bungii, fed on nano- and micro-sized organisms non-selectively throughout the season. However, diatoms were the dominant food resource until May and organisms, such as ciliates were the major resource after May. Daily growth rate was estimated from the Ikeda–Motoda, Huntley–Lopez and Hirst–Sheader models. Since the growth rates were considered to be overestimates for the Huntley–Lopez model and underestimates for the other two models, we applied the weight-specific growth rates previously reported for these species in the Bering Shelf. Surface biomass of Neocalanus increased rapidly in June during the appearance of C5, and a successive increase of overwintering stock was evident in the deeper layer. The deep biomass decreased gradually from September to May during the dormant and reproduction period. N. cristatus has the largest annual mean biomass (2.3 gC m−2), followed by N. plumchrus (1.1) and N. flemingeri (0.4). Daily production rate of Neocalanus varied from 0.4 to 363.4 mgC m−2 day−1, to which N. cristatus was the largest contributor. Annual production was estimated as 11.5 gC m−2 year−1 for N. cristatus, 5.7 for N. plumchrus and 2.1 for N. flemingeri, yielding annual P/B ratio of 5 for each species. The annual production of Neocalanus accounted for 13.2% of the primary production in the Oyashio region. Their fecal pellets were estimated to account for 14.9% (0.7 gC m−2 year−1) of sinking flux of organic carbon at 1000-m depth. Moreover, their export flux by ontogenetic vertical migration, which is not measured by sediment trap observations, is estimated to be 91.5% (4.3 gC m−2 year−1) of carbon flux of sinking particles at 1000-m depth. These results suggest the important role of interzonal migrating copepods in the export flux of carbon.  相似文献   

19.
Data from the first systematic survey of inorganic carbon parameters on a global scale, the GEOSECS program, are compared with those collected during WOCE/JGOFS to study the changes in carbon and other geochemical properties, and anthropogenic CO2 increase in the Atlantic Ocean from the 1970s to the early 1990s. This first data-based estimate of CO2 increase over this period was accomplished by adjusting the GEOSECS data set to be consistent with recent high-quality carbon data. Multiple Linear Regression (MLR) and extended Multiple Linear Regression (eMLR) analyses to these carbon data are applied by regressing DIC with potential temperature, salinity, AOU, silica, and PO4 in three latitudinal regions for the western and eastern basins in the Atlantic Ocean. The results from MLR (and eMLR provided in parentheses) indicate that the mean anthropogenic CO2 uptake rate in the western basin is 0.70 (0.53) mol m?2 yr?1 for the region north of 15°N; 0.53 (0.36) mol m?2 yr?1 for the equatorial region between 15°N and 15°S; and 0.83 (0.35) mol m?2 yr?1 in the South Atlantic south of 15°S. For the eastern basin an estimate of 0.57 (0.45) mol m?2 yr?1 is obtained for the equatorial region, and 0.28 (0.34) mol m?2 yr?1 for the South Atlantic south of 15°S. The results of using eMLR are systematically lower than those from MLR method in the western basin. The anthropogenic CO2 increase is also estimated in the upper thermocline from salinity normalized DIC after correction for AOU along the isopycnal surfaces. For these depths the results are consistent with the CO2 uptake rates derived from both MLR and eMLR methods.  相似文献   

20.
The seasonal and interannual variability of the air–sea CO2 flux (F) in the Atlantic sector of the Barents Sea have been investigated. Data for seawater fugacity of CO2 (fCO2sw) acquired during five cruises in the region were used to identify and validate an empirical procedure to compute fCO2sw from phosphate (PO4), seawater temperature (T), and salinity (S). This procedure was then applied to time series data of T, S, and PO4 collected in the Barents Sea Opening during the period 1990–1999, and the resulting fCO2sw estimates were combined with data for the atmospheric mole fraction of CO2, sea level pressure, and wind speed to evaluate F.The results show that the Atlantic sector of the Barents Sea is an annual sink of atmospheric CO2. The monthly mean uptake increases nearly monotonically from 0.101 mol C m− 2 in midwinter to 0.656 mol C m− 2 in midfall before it gradually decreases to the winter value. Interannual variability in the monthly mean flux was evaluated for the winter, summer, and fall seasons and was found to be ± 0.071 mol C m− 2 month− 1. The variability is controlled mainly through combined variation of fCO2sw and wind speed. The annual mean uptake of atmospheric CO2 in the region was estimated to 4.27 ± 0.68 mol C m− 2.  相似文献   

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