North Pacific dissolved inorganic carbon variations related to the Pacific Decadal Oscillation

Yasunaka, Sayaka; Nojiri, Yukihiro; Nakaoka, Shin Ichiro; Ono, Tsuneo; Mukai, Hitoshi; Usui, Norihisa

doi:10.1002/2013gl058987

Cited by 13 publications

(15 citation statements)

References 49 publications

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“…The PDO-related nutrient variation pattern obtained by this study was similar to but slightly different from the PDO-related DIC variation pattern reported by Yasunaka et al [2014]. In the subtropics, there was a significant DIC signal, but no nutrient signal due to differences in response to salinity change (strong in DIC while weak in nutrients).…”

Section: Interannual Variabilitycontrasting

confidence: 59%

Mapping of sea surface nutrients in the North Pacific: Basin-wide distribution and seasonal to interannual variability

Yasunaka

Nojiri

Nakaoka

et al. 2014

J. Geophys. Res. Oceans

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Monthly maps of sea surface nutrient (phosphate, nitrate, and silicate) concentrations were produced for the North Pacific (10 N-60 N, 120 E-90 W) for the years 2001-2010 using a selforganizing map trained with temperature, salinity, chlorophyll-a concentration, and mixed layer depth. Nutrient sampling was carried out mainly by ships of opportunity, providing good seasonal coverage of the surface ocean. Using the mapping results, we investigated the spatiotemporal variability of surface North Pacific nutrient and dissolved inorganic carbon (DIC) distributions on seasonal and interannual time scales. Nutrient and DIC concentrations were high in the subarctic in winter and low in the subtropics. In the summer, substantial amount of nutrients remained unutilized in subarctic and the northern part of the subarcticsubtropical boundary region while that was not the case in the southern part of the boundary region. In the subtropics, nutrients were almost entirely depleted throughout the year, while DIC concentrations showed a north-south gradient and significant seasonal change. Nutrients and DIC show a large seasonal drawdown in the western subarctic region, while the drawdown in the eastern subarctic region was weaker, especially for silica. The subarctic-subtropical boundary region also showed a large seasonal drawdown, which was most prominent for DIC and less obvious for nitrate and silicate. In the interannual time scale, the Pacific Decadal Oscillation was related to a seesaw pattern between the subarctic-subtropical boundary region and the Alaskan Gyre through the changes in horizontal advection, vertical mixing, and biological production.

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Section: Interannual Variabilitycontrasting

confidence: 59%

Mapping of sea surface nutrients in the North Pacific: Basin-wide distribution and seasonal to interannual variability

Yasunaka

Nojiri

Nakaoka

et al. 2014

J. Geophys. Res. Oceans

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“…A long-term decrease and ENSO-related variation of surface nutrients (phosphate, nitrate, and silicate) and biological production in the subarctic have been reported at several regions in the North Pacific (Freeland et al 1997;Ono et al 2002). A DIC increase in the western subtropics is also observed (Midorikawa et al 2010;Ono et al 2019) Goes et al (2004) and Yasunaka et al (2013Yasunaka et al ( , 2014aYasunaka et al ( , b, 2016 made nutrient and DIC gridded products, and presented their basin-scale distributions and variabilities. However, these products use empirical relationships between nutrient concentrations and environmental variables, such as sea surface temperature (SST).…”

Section: Introductionmentioning

confidence: 94%

Nutrient and dissolved inorganic carbon variability in the North Pacific

et al. 2020

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A compilation of surface water nutrient (phosphate, nitrate, and silicate) and partial pressure of CO 2 (pCO 2) observations from 1961 to 2016 reveals seasonal and interannual variability in the North Pacific. Nutrients and calculated dissolved inorganic carbon (DIC) reach maximum concentrations in March and minimum in August. Nutrient and DIC variability is in-phase (anti-phase) with changes in the mixed layer depth (sea surface temperature) north of 30 °N, and it is anti-phase (in-phase) with changes in Chl-a north of 40 °N (in 30 °N-40 °N). Seasonal drawdown of nutrients and DIC is larger toward the northwest and shows a local maximum in the boundary region between the subarctic and subtropics. Stoichiometric ratios of seasonal drawdown show that, compared to nitrate, silicate drawdown is large in the northwestern subarctic including the Bering and Okhotsk seas, and drawdown of carbon is larger toward the south. Net community production in mixed layer from March to July is estimated to be more than 6 gC/m 2 /mo in the boundary region between the subarctic and subtropics, the western subarctic, the Gulf of Alaska, and the Bering Sea. Nutrient and DIC concentrations vary with the Pacific Decadal Oscillation and the North Pacific Gyre Oscillation which cause changes in horizontal advection and vertical mixing. The DIC trend is positive in all analysis area and large in the western subtropics (> 1.0 μmol/l/yr). Averaged over the analysis area, it is increasing by 0.77 ± 0.03 μmol/l/yr (0.75 ± 0.02 μmol/kg/yr).

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“…As for the case of a 254 , the relationship between a 325 and AOU does not change around AOU = 0 µmol kg −1 . Given that the absorption at 325 nm is due to aromatic compounds (Coble, 1996;Jørgensen et al, 2011), the positive relationship with AOU suggests that a 325 is a tracer for the production of the aromatic humic-like materials that absorb at 320-340 nm and fluoresce at 400-450 nm during the microbial degradation of organic matter (Coble, 1996;Jørgensen et al, 2014;Catalá et al, 2016). Therefore, a 325 could be considered a tracer of the MCP, which postulates the production of refractory DOM as a consequence of the processing of bioavailable organic matter in the oceans (Ogawa et al, 2001;Jiao et al, 2010;Goto et al, 2017).…”

Section: Aou As a Driver Pointing That A 254 And A 325 Represent Diffmentioning

confidence: 99%

Patterns and Drivers of UV Absorbing Chromophoric Dissolved Organic Matter in the Euphotic Layer of the Open Ocean

et al. 2019

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The global distribution of chromophoric dissolved organic matter (CDOM) in the euphotic layer of the Atlantic, Indian, and Pacific oceans (between 35 • N and 40 • S) was analyzed by absorption spectroscopy during the Malaspina 2010 circumnavigation. Absorption coefficients at 254 nm (a 254 ) and 325 nm (a 325 ), indices (a 254 /a 365 ) and spectral slopes (between 275 and 295 nm, S 275−295 ) were calculated from the dissolved fraction of the UV absorption spectra to describe the amount and quality of CDOM. Generalized Additive Models (GAMs) were applied to evaluate the relevance of physical and biogeochemical drivers for the variability of CDOM. Besides the low CDOM values, a first division of our data following the Longhurst's biogeographic classification showed significant differences in CDOM levels among provinces. The lowest values of a 254 and a 325 were found in the oligotrophic gyres, particularly in the Indian Ocean, and the highest in the upwelling areas, particularly in the Equatorial Pacific. Opposite distributions were obtained for S 275−295 and a 254 /a 365 , indicative of higher photobleaching in the gyres. Within each province, whereas a 254 was constant through the photic layer, a 325 increased significantly with depth as a result of the dominance of photobleaching over biological production in the surface layer and the opposite at depth. The Pacific provinces, including the subtropical gyres, showed, however, significantly higher a 325 values, indicative of lower photobleaching/higher biological production. The GAM analysis indicates that a 254 and a 325 were primarily related to chlorophyll a (Chl a), exhibiting a significant positive linear response. Interestingly, Prochlorococcus and Synechococcus abundances were related to these absorption coefficients. Apparent oxygen utilization also contributed to explain the distributions of these absorption coefficients, being inversely related to a 254 and directly related to a 325 . These results are consistent with the premise that a 254 could be a proxy for the concentration of dissolved organic carbon and a 325 for the aromatic by-products of biological degradation. The GAM analysis also shows that a 254 /a 365 and S 275−295 exhibited inverse relationships Frontiers in Marine Science | www.frontiersin.org 1 June 2019 | Volume 6 | Article 320 Iuculano et al. CDOM Drivers in the Euphotic Ocean Layerwith solar radiation, indicating that the biological production of CDOM counteracts photodegradation as solar radiation increases. In summary, whereas photobleaching dictates the vertical distribution of CDOM, Chl a explains the CDOM differences among the photic layer of the tropical and subtropical ocean provinces visited during the circumnavigation.

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North Pacific dissolved inorganic carbon variations related to the Pacific Decadal Oscillation

Cited by 13 publications

References 49 publications

Mapping of sea surface nutrients in the North Pacific: Basin-wide distribution and seasonal to interannual variability

Mapping of sea surface nutrients in the North Pacific: Basin-wide distribution and seasonal to interannual variability

Nutrient and dissolved inorganic carbon variability in the North Pacific

Patterns and Drivers of UV Absorbing Chromophoric Dissolved Organic Matter in the Euphotic Layer of the Open Ocean

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