McKinley
Galen A.
McKinley
Galen A.
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ArticleNorth Pacific carbon cycle response to climate variability on seasonal to decadal timescales(American Geophysical Union, 2006-07-04) McKinley, Galen A. ; Takahashi, Taro ; Buitenhuis, Erik T. ; Chai, Fei ; Christian, James R. ; Doney, Scott C. ; Jiang, Mingshun ; Lindsay, Keith ; Moore, J. Keith ; Le Quere, Corinne ; Lima, Ivan D. ; Murtugudde, Raghu ; Shi, L. ; Wetzel, PatrickClimate variability drives significant changes in the physical state of the North Pacific, and thus there may be important impacts of climate variability on the upper ocean carbon balance across the basin. We address this issue by considering the response of seven biogeochemical ocean models to climate variability in the North Pacific. The models’ upper ocean pCO2 and air-sea CO2 flux respond similarly to climate variability on seasonal to decadal timescales. Modeled seasonal cycles of pCO2 and its temperature and non-temperature driven components at three contrasting oceanographic sites capture the basic features found in observations [Takahashi et al., 2002, 2006; Keeling et al., 2004; Brix et al., 2004]. However, particularly in the Western Subarctic Gyre, the models have difficulty representing the temporal structure of the total pCO2 cycle because it results from the difference of these two large and opposing components. In all but one model, the airsea CO2 flux interannual variability (1σ) in the North Pacific is smaller (ranges across models from 0.03 to 0.11 PgC/yr) than in the Tropical Pacific (ranges across models from 0.08 to 0.19 PgC/yr), and the timeseries of the first or second EOF of the air-sea CO2 flux has a significant correlation with the Pacific Decadal Oscillation (PDO). Though air-sea CO2 flux anomalies are correlated with the PDO, their magnitudes are small (up to ±0.025 PgC/yr (1σ)). Flux anomalies are damped because anomalies in the key drivers of pCO2 (temperature, dissolved inorganic carbon (DIC) and alkalinity) are all of similar magnitude and have strongly opposing effects that damp total pCO2 anomalies.
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ArticleGlobal ocean carbon uptake : magnitude, variability and trends(Copernicus Publications on behalf of the European Geosciences Union, 2013-03-22) Wanninkhof, Rik ; Park, Geun-Ha ; Takahashi, Taro ; Sweeney, Colm ; Feely, Richard A. ; Nojiri, Yukihiro ; Gruber, Nicolas ; Doney, Scott C. ; McKinley, Galen A. ; Lenton, Andrew ; Le Quere, Corinne ; Heinze, Christoph ; Schwinger, Jorg ; Graven, Heather ; Khatiwala, SamarThe globally integrated sea–air anthropogenic carbon dioxide (CO2) flux from 1990 to 2009 is determined from models and data-based approaches as part of the Regional Carbon Cycle Assessment and Processes (RECCAP) project. Numerical methods include ocean inverse models, atmospheric inverse models, and ocean general circulation models with parameterized biogeochemistry (OBGCMs). The median value of different approaches shows good agreement in average uptake. The best estimate of anthropogenic CO2 uptake for the time period based on a compilation of approaches is −2.0 Pg C yr−1. The interannual variability in the sea–air flux is largely driven by large-scale climate re-organizations and is estimated at 0.2 Pg C yr−1 for the two decades with some systematic differences between approaches. The largest differences between approaches are seen in the decadal trends. The trends range from −0.13 (Pg C yr−1) decade−1 to −0.50 (Pg C yr−1) decade−1 for the two decades under investigation. The OBGCMs and the data-based sea–air CO2 flux estimates show appreciably smaller decadal trends than estimates based on changes in carbon inventory suggesting that methods capable of resolving shorter timescales are showing a slowing of the rate of ocean CO2 uptake. RECCAP model outputs for five decades show similar differences in trends between approaches.
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ArticleChallenges of modeling depth-integrated marine primary productivity over multiple decades : a case study at BATS and HOT(American Geophysical Union, 2010-09-15) Saba, Vincent S. ; Friedrichs, Marjorie A. M. ; Carr, Mary-Elena ; Antoine, David ; Armstrong, Robert A. ; Asanuma, Ichio ; Aumont, Olivier ; Bates, Nicholas R. ; Behrenfeld, Michael J. ; Bennington, Val ; Bopp, Laurent ; Bruggeman, Jorn ; Buitenhuis, Erik T. ; Church, Matthew J. ; Ciotti, Aurea M. ; Doney, Scott C. ; Dowell, Mark ; Dunne, John P. ; Dutkiewicz, Stephanie ; Gregg, Watson ; Hoepffner, Nicolas ; Hyde, Kimberly J. W. ; Ishizaka, Joji ; Kameda, Takahiko ; Karl, David M. ; Lima, Ivan D. ; Lomas, Michael W. ; Marra, John F. ; McKinley, Galen A. ; Melin, Frederic ; Moore, J. Keith ; Morel, Andre ; O'Reilly, John ; Salihoglu, Baris ; Scardi, Michele ; Smyth, Tim J. ; Tang, Shilin ; Tjiputra, Jerry ; Uitz, Julia ; Vichi, Marcello ; Waters, Kirk ; Westberry, Toby K. ; Yool, AndrewThe performance of 36 models (22 ocean color models and 14 biogeochemical ocean circulation models (BOGCMs)) that estimate depth-integrated marine net primary productivity (NPP) was assessed by comparing their output to in situ 14C data at the Bermuda Atlantic Time series Study (BATS) and the Hawaii Ocean Time series (HOT) over nearly two decades. Specifically, skill was assessed based on the models' ability to estimate the observed mean, variability, and trends of NPP. At both sites, more than 90% of the models underestimated mean NPP, with the average bias of the BOGCMs being nearly twice that of the ocean color models. However, the difference in overall skill between the best BOGCM and the best ocean color model at each site was not significant. Between 1989 and 2007, in situ NPP at BATS and HOT increased by an average of nearly 2% per year and was positively correlated to the North Pacific Gyre Oscillation index. The majority of ocean color models produced in situ NPP trends that were closer to the observed trends when chlorophyll-a was derived from high-performance liquid chromatography (HPLC), rather than fluorometric or SeaWiFS data. However, this was a function of time such that average trend magnitude was more accurately estimated over longer time periods. Among BOGCMs, only two individual models successfully produced an increasing NPP trend (one model at each site). We caution against the use of models to assess multiannual changes in NPP over short time periods. Ocean color model estimates of NPP trends could improve if more high quality HPLC chlorophyll-a time series were available.
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Working PaperA science plan for carbon cycle research in North American coastal waters. Report of the Coastal CARbon Synthesis (CCARS) community workshop, August 19-21, 2014(Ocean Carbon & Biogeochemistry Program, 2016) Benway, Heather M. ; Alin, Simone R. ; Boyer, Elizabeth ; Cai, Wei-Jun ; Coble, Paula G. ; Cross, Jessica N. ; Friedrichs, Marjorie A. M. ; Goni, Miguel ; Griffith, Peter C. ; Herrmann, Maria ; Lohrenz, Steven E. ; Mathis, Jeremy T. ; McKinley, Galen A. ; Najjar, Raymond G. ; Pilskaln, Cynthia H. ; Siedlecki, Samantha A. ; Smith, Richard A.Relative to their surface area, continental margins represent some of the largest carbon fluxes in the global ocean, but sparse and sporadic sampling in space and time makes these systems difficult to characterize and quantify. Recognizing the importance of continental margins to the overall North American carbon budget, terrestrial and marine carbon cycle scientists have been collaborating on a series of synthesis, carbon budgeting, and modeling exercises for coastal regions of North America, which include the Gulf of Mexico, the Laurentian Great Lakes (LGL), and the coastal waters of the Atlantic, Pacific, and Arctic Oceans. The Coastal CARbon Synthesis (CCARS) workshops and research activities have been conducted over the past several years as a partner activity between the Ocean Carbon and Biogeochemistry (OCB) Program and the North American Carbon Program (NACP) to synthesize existing data and improve quantitative assessments of the North American carbon budget.
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ArticleBiogeochemical protocols and diagnostics for the CMIP6 Ocean Model Intercomparison Project (OMIP)(Copernicus Publications on behalf of the European Geosciences Union, 2017-06-09) Orr, James C. ; Najjar, Raymond G. ; Aumont, Olivier ; Bopp, Laurent ; Bullister, John L. ; Danabasoglu, Gokhan ; Doney, Scott C. ; Dunne, John P. ; Dutay, Jean-Claude ; Graven, Heather ; Griffies, Stephen M. ; John, Jasmin G. ; Joos, Fortunat ; Levin, Ingeborg ; Lindsay, Keith ; Matear, Richard J. ; McKinley, Galen A. ; Mouchet, Anne ; Oschlies, Andreas ; Romanou, Anastasia ; Schlitzer, Reiner ; Tagliabue, Alessandro ; Tanhua, Toste ; Yool, AndrewThe Ocean Model Intercomparison Project (OMIP) focuses on the physics and biogeochemistry of the ocean component of Earth system models participating in the sixth phase of the Coupled Model Intercomparison Project (CMIP6). OMIP aims to provide standard protocols and diagnostics for ocean models, while offering a forum to promote their common assessment and improvement. It also offers to compare solutions of the same ocean models when forced with reanalysis data (OMIP simulations) vs. when integrated within fully coupled Earth system models (CMIP6). Here we detail simulation protocols and diagnostics for OMIP's biogeochemical and inert chemical tracers. These passive-tracer simulations will be coupled to ocean circulation models, initialized with observational data or output from a model spin-up, and forced by repeating the 1948–2009 surface fluxes of heat, fresh water, and momentum. These so-called OMIP-BGC simulations include three inert chemical tracers (CFC-11, CFC-12, SF6) and biogeochemical tracers (e.g., dissolved inorganic carbon, carbon isotopes, alkalinity, nutrients, and oxygen). Modelers will use their preferred prognostic BGC model but should follow common guidelines for gas exchange and carbonate chemistry. Simulations include both natural and total carbon tracers. The required forced simulation (omip1) will be initialized with gridded observational climatologies. An optional forced simulation (omip1-spunup) will be initialized instead with BGC fields from a long model spin-up, preferably for 2000 years or more, and forced by repeating the same 62-year meteorological forcing. That optional run will also include abiotic tracers of total dissolved inorganic carbon and radiocarbon, CTabio and 14CTabio, to assess deep-ocean ventilation and distinguish the role of physics vs. biology. These simulations will be forced by observed atmospheric histories of the three inert gases and CO2 as well as carbon isotope ratios of CO2. OMIP-BGC simulation protocols are founded on those from previous phases of the Ocean Carbon-Cycle Model Intercomparison Project. They have been merged and updated to reflect improvements concerning gas exchange, carbonate chemistry, and new data for initial conditions and atmospheric gas histories. Code is provided to facilitate their implementation.
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ArticleContribution of ocean, fossil fuel, land biosphere, and biomass burning carbon fluxes to seasonal and interannual variability in atmospheric CO2(American Geophysical Union, 2008-02-12) Nevison, Cynthia D. ; Mahowald, Natalie M. ; Doney, Scott C. ; Lima, Ivan D. ; van der Werf, Guido R. ; Randerson, James T. ; Baker, David F. ; Kasibhatla, Prasad S. ; McKinley, Galen A.Seasonal and interannual variability in atmospheric carbon dioxide (CO2) concentrations was simulated using fluxes from fossil fuel, ocean and terrestrial biogeochemical models, and a tracer transport model with time-varying winds. The atmospheric CO2 variability resulting from these surface fluxes was compared to observations from 89 GLOBALVIEW monitoring stations. At northern hemisphere stations, the model simulations captured most of the observed seasonal cycle in atmospheric CO2, with the land tracer accounting for the majority of the signal. The ocean tracer was 3–6 months out of phase with the observed cycle at these stations and had a seasonal amplitude only ∼10% on average of observed. Model and observed interannual CO2 growth anomalies were only moderately well correlated in the northern hemisphere (R ∼ 0.4–0.8), and more poorly correlated in the southern hemisphere (R < 0.6). Land dominated the interannual variability (IAV) in the northern hemisphere, and biomass burning in particular accounted for much of the strong positive CO2 growth anomaly observed during the 1997–1998 El Niño event. The signals in atmospheric CO2 from the terrestrial biosphere extended throughout the southern hemisphere, but oceanic fluxes also exerted a strong influence there, accounting for roughly half of the IAV at many extratropical stations. However, the modeled ocean tracer was generally uncorrelated with observations in either hemisphere from 1979–2004, except during the weak El Niño/post-Pinatubo period of the early 1990s. During that time, model results suggested that the ocean may have accounted for 20–25% of the observed slowdown in the atmospheric CO2 growth rate.
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Working PaperSynthesis and Intercomparison of Ocean Carbon Uptake in CMIP6 Models workshop report, December 8-9, 2018 Washington, DC( 2019-04) Dunne, John P. ; Romanou, Anastasia ; McKinley, Galen A. ; Long, Matthew C. ; Doney, Scott C.From the Introduction: This workshop served as an important opportunity to improve communication between ocean carbon cycle scientists, both across sub-disciplines centering on observations, theory, models, and synthesis, and across career levels from graduate student to senior scientist. Participants shared questions, knowledge, and perceived challenges on the weaknesses of CMIP5 and CMIP6 models, potential observational constraints, and emerging theory. The workshop provided many opportunities for the development of collaborative project ideas through oral, poster, and moderated group discussion sessions, with a major emphasis on the upcoming December 2019 manuscript submission deadline to contribute to the IPCC Sixth Assessment. Participants also provided feedback to modeling centers on novel ways to push this community and the models forward, thinking beyond the currently planned suite of CMIP6 modeling activities.
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DatasetUpper Ocean Box Model which solves for the time change of Dissolved Inorganic Carbon (DIC) in single upper ocean box(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2021-05-10) McKinley, Galen A.The box model solves for the time change of Dissolved Inorganic Carbon (DIC) in single upper ocean box. The upper ocean box model is forced by observed atmospheric pCO2 and temperature. It calculates the pCO2 and air-sea CO2 flux. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/840371
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PresentationTemporal and spatial perspectives on the fate of anthropogenic carbon : a carbon cycle slide deck for broad audiences(Ocean Carbon & Biogeochemistry Program, 2015-12-08) Khatiwala, Samar ; DeVries, Timothy ; Cook, Jack ; McKinley, Galen A. ; Carlson, Craig A. ; Benway, Heather M.This slide deck was developed to inform broader scientific, as well as general audiences about the role of the ocean in the global carbon cycle, including key sinks and sources of anthropogenic carbon and how they have evolved through time and space.
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Working PaperReview of US GO-SHIP (Global Oceans Shipboard Hydrographic Investigations Program) An OCB and US CLIVAR Report(Woods Hole Oceanographic Institution, 2019-10) Bingham, Frederick ; Juranek, Laurie W. ; Mazloff, Matthew R. ; McKinley, Galen A. ; Nelson, Norman B. ; Wijffels, Susan E.The following document constitutes a review of the US GO-SHIP program, performed under the auspices of US Climate Variability and Predictability (CLIVAR) and Ocean Carbon Biogeochemistry (OCB) Programs. It is the product of an external review committee, charged and assembled by US CLIVAR and OCB with members who represent the interests of the programs and who are independent of US GO-SHIP support, which spent several months gathering input and drafting this report. The purpose of the review is to assess program planning, progress, and opportunities in collecting, providing, and synthesizing high quality hydrographic data to advance the scientific research goals of US CLIVAR and OCB.
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ArticleSatellite sensor requirements for monitoring essential biodiversity variables of coastal ecosystems(John Wiley & Sons, 2018-03-06) Muller-Karger, Frank E. ; Hestir, Erin ; Ade, Christiana ; Turpie, Kevin ; Roberts, Dar A. ; Siegel, David A. ; Miller, Robert J. ; Humm, David ; Izenberg, Noam ; Keller, Mary ; Morgan, Frank ; Frouin, Robert ; Dekker, Arnold G. ; Gardner, Royal ; Goodman, James ; Schaeffer, Blake ; Franz, Bryan A. ; Pahlevan, Nima ; Mannino, Antonio ; Concha, Javier A. ; Ackleson, Steven G. ; Cavanaugh, Kyle C. ; Romanou, Anastasia ; Tzortziou, Maria ; Boss, Emmanuel S. ; Pavlick, Ryan ; Freeman, Anthony ; Rousseaux, Cecile S. ; Dunne, John P. ; Long, Matthew C. ; Salas, Eduardo Klein ; McKinley, Galen A. ; Goes, Joachim I. ; Letelier, Ricardo M. ; Kavanaugh, Maria T. ; Roffer, Mitchell ; Bracher, Astrid ; Arrigo, Kevin R. ; Dierssen, Heidi M. ; Zhang, Xiaodong ; Davis, Frank W. ; Best, Benjamin D. ; Guralnick, Robert P. ; Moisan, John R. ; Sosik, Heidi M. ; Kudela, Raphael M. ; Mouw, Colleen B. ; Barnard, Andrew H. ; Palacios, Sherry ; Roesler, Collin S. ; Drakou, Evangelia G. ; Appeltans, Ward ; Jetz, WalterThe biodiversity and high productivity of coastal terrestrial and aquatic habitats are the foundation for important benefits to human societies around the world. These globally distributed habitats need frequent and broad systematic assessments, but field surveys only cover a small fraction of these areas. Satellite‐based sensors can repeatedly record the visible and near‐infrared reflectance spectra that contain the absorption, scattering, and fluorescence signatures of functional phytoplankton groups, colored dissolved matter, and particulate matter near the surface ocean, and of biologically structured habitats (floating and emergent vegetation, benthic habitats like coral, seagrass, and algae). These measures can be incorporated into Essential Biodiversity Variables (EBVs), including the distribution, abundance, and traits of groups of species populations, and used to evaluate habitat fragmentation. However, current and planned satellites are not designed to observe the EBVs that change rapidly with extreme tides, salinity, temperatures, storms, pollution, or physical habitat destruction over scales relevant to human activity. Making these observations requires a new generation of satellite sensors able to sample with these combined characteristics: (1) spatial resolution on the order of 30 to 100‐m pixels or smaller; (2) spectral resolution on the order of 5 nm in the visible and 10 nm in the short‐wave infrared spectrum (or at least two or more bands at 1,030, 1,240, 1,630, 2,125, and/or 2,260 nm) for atmospheric correction and aquatic and vegetation assessments; (3) radiometric quality with signal to noise ratios (SNR) above 800 (relative to signal levels typical of the open ocean), 14‐bit digitization, absolute radiometric calibration <2%, relative calibration of 0.2%, polarization sensitivity <1%, high radiometric stability and linearity, and operations designed to minimize sunglint; and (4) temporal resolution of hours to days. We refer to these combined specifications as H4 imaging. Enabling H4 imaging is vital for the conservation and management of global biodiversity and ecosystem services, including food provisioning and water security. An agile satellite in a 3‐d repeat low‐Earth orbit could sample 30‐km swath images of several hundred coastal habitats daily. Nine H4 satellites would provide weekly coverage of global coastal zones. Such satellite constellations are now feasible and are used in various applications.
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ArticleAn assessment of the Atlantic and Arctic sea–air CO2 fluxes, 1990–2009(Copernicus Publications on behalf of the European Geosciences Union, 2013-01-29) Schuster, Ute ; McKinley, Galen A. ; Bates, Nicholas R. ; Chevallier, Frédéric ; Doney, Scott C. ; Fay, A. R. ; Gonzalez-Davila, M. ; Gruber, Nicolas ; Jones, S. ; Krijnen, J. ; Landschutzer, Peter ; Lefevre, N. ; Manizza, Manfredi ; Mathis, Jeremy T. ; Metzl, Nicolas ; Olsen, Are ; Rios, Aida F. ; Rodenbeck, C. ; Santana-Casiano, J. M. ; Takahashi, Taro ; Wanninkhof, Rik ; Watson, Andrew J.The Atlantic and Arctic Oceans are critical components of the global carbon cycle. Here we quantify the net sea–air CO2 flux, for the first time, across different methodologies for consistent time and space scales for the Atlantic and Arctic basins. We present the long-term mean, seasonal cycle, interannual variability and trends in sea–air CO2 flux for the period 1990 to 2009, and assign an uncertainty to each. We use regional cuts from global observations and modeling products, specifically a pCO2-based CO2 flux climatology, flux estimates from the inversion of oceanic and atmospheric data, and results from six ocean biogeochemical models. Additionally, we use basin-wide flux estimates from surface ocean pCO2 observations based on two distinct methodologies. Our estimate of the contemporary sea–air flux of CO2 (sum of anthropogenic and natural components) by the Atlantic between 40° S and 79° N is −0.49 ± 0.05 Pg C yr−1, and by the Arctic it is −0.12 ± 0.06 Pg C yr−1, leading to a combined sea–air flux of −0.61 ± 0.06 Pg C yr−1 for the two decades (negative reflects ocean uptake). We do find broad agreement amongst methodologies with respect to the seasonal cycle in the subtropics of both hemispheres, but not elsewhere. Agreement with respect to detailed signals of interannual variability is poor, and correlations to the North Atlantic Oscillation are weaker in the North Atlantic and Arctic than in the equatorial region and southern subtropics. Linear trends for 1995 to 2009 indicate increased uptake and generally correspond between methodologies in the North Atlantic, but there is disagreement amongst methodologies in the equatorial region and southern subtropics.