Updated methods for global locally interpolated estimation of alkalinity, pH, and nitrate

Carter, Brendan R.; Feely, Richard A.; Williams, Nancy L.; Dickson, Andrew G.; Fong, Michael B.; Takeshita, Yuichiro

doi:10.1002/lom3.10232

Cited by 149 publications

(234 citation statements)

References 35 publications

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“…We present updated estimates of Pacific C anth inventories and accumulation rates determined using updates to the eMLR approach combining several recommendations from the literature (Carter, Feely, Williams, et al, 2017;Clement & Gruber, 2018;Thacker, 2012). Our estimates are obtained by comparing measurements from a section to measurements from subsequent occupations of that same section.…”

Section: Discussionmentioning

confidence: 99%

“…In situ conditions are used for all other carbonate system calculations to quantify the impacts of C anth on pH and aragonite saturation state (Ω) where C anth is found. Where surface A T is not measured, it is estimated from S , θ , and AOU using Locally Interpolated A T Regression (equation 7; Carter, Feely, Williams, et al, ). Uncertainties in these calculations are dominated by errors in the assumed p CO 2 or DIC property changes and are relatively insensitive to uncertainties in the estimated A T .…”

Section: Methodsmentioning

confidence: 99%

“…A new method, related to the multiparametric interpolation of Velo et al (2010), is used to extrapolate the total C anth estimates to the basin scale. A locally interpolated regression (LIR) (Carter, Feely, Williams, et al, 2017) is created relating C anth to S, θ, the depth, the years since 1995 (Y 1995 , with a maximum of 10), and the years since 2005 (Y 2005 , with a minimum of 0). As the LIR is used solely for basin-wide estimation, we only briefly note that the methods of its creation in all ways mirror those of Locally Interpolated A T Regression version 2 as presented by (Carter, Feely, Williams, et al, 2017), with the following exceptions: (1) Only a single regression is used.…”

Section: Extending C Anth Accumulation Rates To Total C Anthmentioning

confidence: 99%

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Pacific Anthropogenic Carbon Between 1991 and 2017

Carter

Feely

Wanninkhof

et al. 2019

Global Biogeochemical Cycles

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We estimate anthropogenic carbon (Canth) accumulation rates in the Pacific Ocean between 1991 and 2017 from 14 hydrographic sections that have been occupied two to four times over the past few decades, with most sections having been recently measured as part of the Global Ocean Ship‐based Hydrographic Investigations Program. The rate of change of Canth is estimated using a new method that combines the extended multiple linear regression method with improvements to address the challenges of analyzing multiple occupations of sections spaced irregularly in time. The Canth accumulation rate over the top 1,500 m of the Pacific increased from 8.8 (±1.1, 1σ) Pg of carbon per decade between 1995 and 2005 to 11.7 (±1.1) PgC per decade between 2005 and 2015. For the entire Pacific, about half of this decadal increase in the accumulation rate is attributable to the increase in atmospheric CO2, while in the South Pacific subtropical gyre this fraction is closer to one fifth. This suggests a substantial enhancement of the accumulation of Canth in the South Pacific by circulation variability and implies that a meaningful portion of the reinvigoration of the global CO2 sink that occurred between ~2000 and ~2010 could be driven by enhanced ocean Canth uptake and advection into this gyre. Our assessment suggests that the accuracy of Canth accumulation rate reconstructions along survey lines is limited by the accuracy of the full suite of hydrographic data and that a continuation of repeated surveys is a critical component of future carbon cycle monitoring.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Extending C Anth Accumulation Rates To Total C Anthmentioning

confidence: 99%

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Pacific Anthropogenic Carbon Between 1991 and 2017

Carter

Feely

Wanninkhof

et al. 2019

Global Biogeochemical Cycles

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“…The pH data collected by the profiling floats (Figure S1) were combined with total alkalinity ( A T ) empirically estimated using the LIARv2 method (Carter et al, ; Figure S2) to calculate p CO

_{2}^{ocn}

in the surface layer (Figure S3). All float data used in this study, including estimated A T and calculated p CO

_{2}^{ocn}

, are publicly available (Johnson et al, ).…”

Section: Float‐based Air‐sea Co2 Flux Estimatesmentioning

confidence: 99%

Autonomous Biogeochemical Floats Detect Significant Carbon Dioxide Outgassing in the High‐Latitude Southern Ocean

Gray

Johnson

Bushinsky

et al. 2018

Geophysical Research Letters

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Although the Southern Ocean is thought to account for a significant portion of the contemporary oceanic uptake of carbon dioxide (CO2), flux estimates in this region are based on sparse observations that are strongly biased toward summer. Here we present new estimates of Southern Ocean air‐sea CO2 fluxes calculated with measurements from biogeochemical profiling floats deployed by the Southern Ocean Carbon and Climate Observations and Modeling project during 2014–2017. Compared to ship‐based CO2 flux estimates, the float‐based fluxes find significantly stronger outgassing in the zone around Antarctica where carbon‐rich deep waters upwell to the surface ocean. Although interannual variability contributes, this difference principally stems from the lack of autumn and winter ship‐based observations in this high‐latitude region. These results suggest that our current understanding of the distribution of oceanic CO2 sources and sinks may need revision and underscore the need for sustained year‐round biogeochemical observations in the Southern Ocean.

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“…Ultraviolet spectrophotometer nitrate sensors (Johnson et al, 2013;Johnson & Coletti, 2002) were deployed on the two BGC-Argo floats. Nitrate concentrations ([NO 3 ], in μmol/kg) were calculated according to the Argo data management protocol (http://doi.org/10.13155/46121), and data were corrected using the locally interpolated nitrate regression of Carter et al (2018) (as described in Johnson et al, 2017). A comparison was done between deep [NO 3 ] values (average value between 950 and 1,000 m, supposedly stable over years) from floats and from the World Ocean Atlas climatology 2009 (Garcia et al, 2010).…”

Section: Nitrate Concentration and Annual Net Community Production Esmentioning

confidence: 99%

Assessing Phytoplankton Activities in the Seasonal Ice Zone of the Greenland Sea Over an Annual Cycle

et al. 2018

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In seasonal ice zones (SIZs), such as the one of the Greenland Sea, the sea ice growth in winter and subsequent melting in summer influence the phytoplankton activity. However, studies assessing phytoplankton activities over complete annual cycles and at a fine temporal resolution are lacking in this environment. Biogeochemical‐Argo floats, which are able to sample under the ice, were used to collect physical and biogeochemical data along vertical profiles and at 5‐day resolution during two complete annual cycles in the Greenland Sea SIZ. Three phytoplankton activity phases were distinct within an annual cycle: one under ice, a second at the ice edge, and a third one around an open‐water subsurface chlorophyll maximum. As expected, the light and nitrate availabilities controlled the phytoplankton activity and the establishment of these phases. On average, most of the annual net community production occurred equally under ice and at the ice edge. The open‐water subsurface chlorophyll maximum phase contribution, on the other hand, was much smaller. Phytoplankton biomass accumulation and production thus occur over a longer period than might be assumed if under ice blooms were neglected. This also means that satellite‐based estimates of phytoplankton biomass and production in this SIZ are likely underestimated. Simulations with the Arctic‐based physical‐biologically coupled SINMOD model suggest that most of the annual net community production in this SIZ results from local processes rather than due to advection of nitrate from the East Greenland and Jan Mayen Currents.

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Updated methods for global locally interpolated estimation of alkalinity, pH, and nitrate

Abstract: We have taken advantage of the release of version 2

Cited by 149 publications

References 35 publications

Pacific Anthropogenic Carbon Between 1991 and 2017

Pacific Anthropogenic Carbon Between 1991 and 2017

Autonomous Biogeochemical Floats Detect Significant Carbon Dioxide Outgassing in the High‐Latitude Southern Ocean

Assessing Phytoplankton Activities in the Seasonal Ice Zone of the Greenland Sea Over an Annual Cycle

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