Upper Ocean Control on the Solubility Pump Of

Total Page:16

File Type:pdf, Size:1020Kb

Upper Ocean Control on the Solubility Pump Of Journalof MarineResearch, 61, 465–489, 2003 Upper ocean controlon the solubility pump of CO 2 byTakamitsu Ito 1 andMichael J. Follows 1 ABSTRACT Wedevelop and test a theoryfor therelationship of atmospheric pCO2 andthe solubility pump of CO2 inan abioticocean. The solubility pump depends on thehydrographic structure of theocean and thedegreeof saturation of thewaters. The depth of thermoclinesets the relative volume of warmand coldwaters, which sets the mean solubility of CO 2 intheocean. The degree of saturation depends on thesurfaceresidence time of the waters. Wedevelop a theorydescribing how atmosphericCO 2 varieswith diapycnal diffusivity and wind stressin asimple,coupled atmosphere-ocean carbon cycle, which builds on established thermocline theory.We consider two limit cases for thermocline circulation: the diffusive thermocline and the ventilatedthermocline. In the limit of a purelydiffusive thermocline (no wind-driven gyres), 1 /3 atmospheric pCO2 increasesin proportionto the depth of thermoclinewhich scales as k , where k isthe diapycnal mixing rate coef cient. In the wind-driven, ventilated thermocline limit, the 1 / 2 ventilatedthermocline theory suggests the thickness of thethermocline varies as we k . Moreover, surfaceresidence times are shorter, and subducted waters are undersaturated. The degree of undersaturationis proportional to the Ekman pumping rate, we k ,formoderate amplitudes of we k . 3 / 2 Hence,atmospheric pCO2 varies as we k formoderate ranges of surface wind stress. Numerical experimentswith an ocean circulation and abiotic carbon cycle model con rm these limit case scalingsand illustrate their combined effect. The numerical experiments suggest that plausible variationsin thewind forcing and diapycnal diffusivity could lead to changesin atmospheric pCO2 ofasmuchas 30ppmv.The deep ocean carbon reservoir is insensitiveto changesin thewind, due to compensationbetween the degree of saturation and the equilibrium carbon concentration. Conse- quently,the sensitivity of atmospheric pCO2 towind-stressforcing is dominated by thechanges in theupper ocean, in direct contrast to the sensitivity to surface properties, such as temperature and alkalinity,which is controlled by thedeep ocean reservoir. 1.Introduction Thepartitioning of carbonbetween oceanic and atmospheric reservoirs and its depen- denceon thecirculation and climate of theoceans has been studied extensively due to the likelyrole of theoceans in modulatingatmospheric CO 2 onglacial-interglacialtimescales (reviewedby Sigmanand Boyle,2000) andthe current oceanic sink of fossilfuel CO 2 from theatmosphere (e.g. Gruber et al., 1996).While it seems clear that the oceans play a signicant role with regard to bothof theseissues, much remains to beunderstood. 1.Program in Atmospheres, Oceans andClimate, Massachusetts Instituteof Technology, Cambridge, Massachusetts 02139,U.S.A. email:[email protected] 465 466 Journalof MarineResearch [61, 4 Theinventory of carbons in the ocean is largely controlled by two important mecha- nisms:the solubility and biological pumps (Volk and Hoffert, 1985).The solubility pump re ectsthe temperature dependence of solubilityof CO 2 andthermal strati cationof the ocean.Cold deep waters aregenerally enriched in dissolvedinorganic carbon (hereafter, C) inpartdue to theirhigher solubility. For areviewof oceancarbonate system, see Stumm andMorgan (1996). The biological pump involves production and dissolution of organic molecules.Photosynthesis occurs in the euphotic layer, converting inorganic carbon and nutrientsto organic matter. Some organic matter leaves the euphotic layer as sinking particles,and it isremineralized in the oceaninterior. Both solubility and biological pumps tendto increase the deep water C concentration,creating a verticalgradient of C. Boxmodel studies in the 1980 ’ssupportedthe notion of adominantrole for thehigh latitudeoceans in controllingatmospheric pCO2 (Sarmientoand Toggweiler, 1984; Knox andMcElroy, 1984; Siegenthaler and Wenk, 1984), largely through the biological pump. Recentstudies with three-dimensional ocean circulation and biogeochemistry models (Bacastow,1995; Broecker et al., 1999;Archer et al., 2000)suggest that atmospheric pCO2 alsoshows a greatersensitivity to low latitude surface ocean properties than had previouslybeen accepted. Archer et al. (2000)suggest that this might be due to the parameterizationsof subgrid-scalemixing and diapycnal mixing in the ocean. Toggweiler et al. (2003)found that the sensitivity of atmospheric CO 2 tolow latitude surface propertiesin box models depends on the representation of deep water formation, and showedthat the boxmodelscan be sensitiveto low latitudes by an adjustment in theareaof highlatitude surface ocean. Alternatively, Follows et al. (2002),using an idealized general circulationand abiotic carbon cycle model (Fig. 1), showed that the wind-driven circula- tionenhances the sensitivity of atmospheric pCO2 tolow latitude surface properties by creatinga poolof relativelywarm waters intheventilated thermocline which inherit their propertiesfrom themid-latitude surface. The model, which conserves the total amount of carbonin ocean and atmosphere, also illustrated a strongsensitivity of atmospheric pCO2 tothepresence or absence of wind forcing. InFigure 1, we illustrateresults from thatnumerical model, details of which may be foundin Follows et al. (2002).Brie y,theexperiments are performedwith the MIT ocean model con gured in a 60° longitudeby 90 ° latitudebasin at 3 ° 3 3° resolution,with 15 verticallevels. It isoverlainby anabioticcarbon cycle model which is coupledto asimple atmosphericreservoir of CO 2.Carbonatechemistry is explicitly solved and the air-sea exchangeof CO 2 isparameterizedwith a uniformgas transfercoef cient.In Follows et al. (2002),we compareexperiments with thermohaline forcing only to those with both thermohalineand wind forcing. The meridional overturning circulation and thermal structureof the model in these two cases is shown in Figure 2. The model resolves the ventilatedthermocline reasonably well. When wind forcing is present, the ocean gyres spin upandthe warm lensof thesubtropical thermocline develops. Though atmospheric pCO2 increasedwith the introduction of the wind forcing, the mean ocean temperature (and therefore,solubility) did not change signi cantly.The increase in atmospheric CO 2 was 2003] Ito& Follows:Solubility pump of CO 2 467 Figure1. Abiotic sector model of ocean-atmosphere carbon cycle: (a) Surface currents and differencein partial pressure of CO 2 acrossthe sea surface in the sector model without wind forcing.(b) Surfacecurrents and difference in partial pressure of CO 2 acrossthe seasurface in the sectormodel with strong wind forcing. (c) Difference in zonally averaged C concentration (mol m2 3 )betweenthe model with strong wind forcing and the model with no windforcing. attributableto thewaters ofthesubtropical thermocline becoming signi cantlyundersatu- rated.The surface currents are slow in the model without wind-forcing (Fig. 1a), the residencetime of water parcelsat the surface is long, and the surface ocean is close to equilibriumwith the atmosphere. In the wind-driven model the surface currents are swift (Fig.1b), the air-sea equilibration time scale and the residence time of surface waters are comparable.Waters of theventilated thermocline are signi cantlyundersaturated due to thestrong cooling in thewestern boundary current. Since the thermocline is depletedin C, bymass conservation,carbon must be transferredto theatmosphere. Figure 1c illustrates thedifference in C intheupper ocean between the two cases. Thesenumerical experiments suggested a potentiallysigni cantrole for theventilated thermoclinein modulating atmospheric CO 2 ondecadal and longer timescales, but motivatesthe broad questions: What are the physical controls on the solubility pump of carbonin the oceans? Can we providea generaltheory of itsdependence on wind-stress 468 Journalof MarineResearch [61, 4 Figure2. Meridional overturning circulation (Sv) and potential temperature ( °C)forthe sector model(a, c) without wind forcing and (b, d) with strong wind forcing (maximum wind-stress 0.2 N m22 ). forcingand diapycnal mixing rates? How mightthe solubility pump respond to climatic change,through changes to these physical properties? Inthis study we seekto understand how the physical structures and processes of the oceancontrol the solubility pump of CO 2.For simplicityand clarity we focuson an abiotic ocean.We developscalings which relate the storage of carbon in the ocean and, thus, atmospheric pCO2 todiapycnal mixing and Ekman pumping rates. We demonstratethat thesescalings accurately predict the behavior of an idealized, three-dimensional, ocean- atmospherecarbon cycle model (Follows et al., 2002).Over areasonablerange of diapycnaldiffusivity and wind-stress, atmospheric pCO2 variesby as much as 30ppmv. Thissuggests a possiblysigni cantrole for thewind-driven gyres in modulating atmo- spheric CO2 ondecadaltimescales, and even with regard to glacial-interglacialchange. It alsoprovides the basis for adeeperunderstanding of the differences between more complexnumerical simulations of theoceans. InSection 2 we reviewthe mass balanceof carbon in a simpli ed,abiotic ocean- atmospheresystem. In Section 3 we brie yreviewsome relevant aspects of thetheory of 2003] Ito& Follows:Solubility pump of CO 2 469 thermoclinethickness. We outlinethe scaling arguments which relate atmospheric pCO2, diapycnalmixing and Ekman pumping in Section
Recommended publications
  • Phytoplankton As Key Mediators of the Biological Carbon Pump: Their Responses to a Changing Climate
    sustainability Review Phytoplankton as Key Mediators of the Biological Carbon Pump: Their Responses to a Changing Climate Samarpita Basu * ID and Katherine R. M. Mackey Earth System Science, University of California Irvine, Irvine, CA 92697, USA; [email protected] * Correspondence: [email protected] Received: 7 January 2018; Accepted: 12 March 2018; Published: 19 March 2018 Abstract: The world’s oceans are a major sink for atmospheric carbon dioxide (CO2). The biological carbon pump plays a vital role in the net transfer of CO2 from the atmosphere to the oceans and then to the sediments, subsequently maintaining atmospheric CO2 at significantly lower levels than would be the case if it did not exist. The efficiency of the biological pump is a function of phytoplankton physiology and community structure, which are in turn governed by the physical and chemical conditions of the ocean. However, only a few studies have focused on the importance of phytoplankton community structure to the biological pump. Because global change is expected to influence carbon and nutrient availability, temperature and light (via stratification), an improved understanding of how phytoplankton community size structure will respond in the future is required to gain insight into the biological pump and the ability of the ocean to act as a long-term sink for atmospheric CO2. This review article aims to explore the potential impacts of predicted changes in global temperature and the carbonate system on phytoplankton cell size, species and elemental composition, so as to shed light on the ability of the biological pump to sequester carbon in the future ocean.
    [Show full text]
  • Design of OCMIP-2 Simulations of Chlorofluorocarbons, the Solubility
    Design of OCMIP-2 simulations of chlorofluorocarbons, the solubility pump and common biogeochemistry Raymond Najjar and James Orr July 27, 1998 OUTLINE 1. Introduction 2. Air-sea gas transfer 2.1. Gas saturation concentrations 2.2. Gas transfer velocity 3. Carbon dioxide system computations 3.1. Choice of CO2 dissociation constants 3.2. Governing equations 3.2.1. Equilibrium expressions 3.2.2. Total inorganic species 3.2.3. Definition of alkalinity 3.3. Computational scheme 4. Direct impact of fresh water fluxes 5. CFC-11 and CFC-12 simulation design 6. Solubility pump design 7. Common biogeochemical model design 7.1. Phosphorus 7.2. Oxygen 7.3. Calcium carbonate 7.4. Dissolved inorganic carbon and alkalinity 7.5. Initial conditions and spin up Appendix: Computation of monthly climatology of u2 1. Introduction The success of OCMIP-2 depends critically upon carefully designed and coordinated sim- ulations of the carbon cycle and related processes. Two important criteria must be met. First, the biogeochemical parameterizations chosen should be the most appropriate to meet the goals of the simulation. These parameterizations should be based upon a careful survey of the literature and modeling experience. The purpose of this document is to describe and justify the parameteriza- tions chosen for OCMIP-2 simulations of chlorofluorocarbons, the solubility pump and common biogeochemistry. This document will be revised or amended at a later date to include designs of simulations of radiocarbon, anthropogenic CO2 uptake and “pulse” inputs of CO2 to the ocean. The second important criterion to be met is that individual modeling groups use the exact same biogeochemical parameterizations.
    [Show full text]
  • Ocean Storage
    12 Ocean storage 12.1 Introduction As described in Chapter 2, the world’s oceans contain an estimated 39,000 Gt-C (143,000Gt-CO2), 50 times more than the atmospheric inventory, and are estimated to have taken up almost 38% (500Gt-CO2) of the 1300Gt of anthropogenic CO2 emissions over the past two centuries. Options that have been investigated to store carbon by increasing the oce­ anic inventory are described in this chapter, including biological (fertilization), chemical (reduction of ocean acidity, accelerated limestone weathering), and physical methods (CO2 dissolution, supercritical CO2 pools in the deep ocean). 12.2 Physical, chemical, and biological fundamentals 12.2.1 Physical properties of CO2 in seawater The behavior of CO2 released directly into seawater will depend primarily on the pressure (i.e., depth) and temperature of the water into which it is released. The key properties are: l The liquefaction pressure at a given temperature: the point at which with increasing pressure, gaseous CO2 will liquefy l The variation of CO2 liquid density with pressure, which determines its buoyancy relative to seawater l The depth and temperature at which CO2 hydrates will form Saturation pressure At temperatures of 0–10°C, CO2 will liquefy at pressures of 4–5MPa, corre­ sponding to water depths of ~400–500m, with a liquid density of 860kg per m3 3 at 10°C and 920kg per m at 0°C. At this depth liquid CO2 will therefore be positively buoyant, and free liquid droplets will rise and evaporate into gas bubbles as pressure drops below the saturation pressure.
    [Show full text]
  • Sensitivities of Marine Carbon Fluxes to Ocean Change
    Sensitivities of marine carbon fluxes to ocean change Ulf Riebesell1, Arne Ko¨ rtzinger, and Andreas Oschlies Marine Biogeochemistry, Leibniz Institute of Marine Sciences, IFM-GEOMAR, Du¨sternbrooker Weg 20, 24105 Kiel, Germany Edited by Hans Joachim Schellnhuber, Potsdam Institute for Climate Impact Research, Potsdam, Germany, and approved August 31, 2009 (received for review December 29, 2008) Throughout Earth’s history, the oceans have played a dominant role in the climate system through the storage and transport of heat and the exchange of water and climate-relevant gases with the atmosphere. The ocean’s heat capacity is Ϸ1,000 times larger than that of the atmosphere, its content of reactive carbon more than 60 times larger. Through a variety of physical, chemical, and biological processes, the ocean acts as a driver of climate variability on time scales ranging from seasonal to interannual to decadal to glacial–interglacial. The same processes will also be involved in future responses of the ocean to global change. Here we assess the responses of the seawater carbon- ate system and of the ocean’s physical and biological carbon pumps to (i) ocean warming and the associated changes in vertical mixing and overturning circulation, and (ii) ocean acidification and carbonation. Our analysis underscores that many of these responses have the potential for significant feedback to the climate system. Because several of the underlying processes are interlinked and nonlinear, the sign and magnitude of the ocean’s carbon cycle feedback to climate change is yet unknown. Understanding these processes and their sen- sitivities to global change will be crucial to our ability to project future climate change.
    [Show full text]
  • How Biological and Solubility Pumps Influence the Sequestration in the Black Sea and in the Eastern Mediterranean?
    Natural Marine CO2 Sequestration: How Biological and Solubility Pumps Influence the Sequestration in the Black Sea and in the Eastern Mediterranean? by Dr. Ayşen YILMAZ Professor in Chemical Oceanography Middle East Technical University, Institute of Marine Sciences, Turkey E-mail: [email protected] June 13, 2012 - METU Atmospheric CO2 is increasing as mankind burns of fossil fuels. This presents serious environmental problems with respect to marine environments. Forests and oceans naturally sequestrate (capture) about half of the atmospheric CO2 (5 billions tons of CO2 globally every year). The oceans portion decreased from 30 % to 25 % since 1960 (till 2006). Reasons: . Strong winds and storms (Decrease in pCO2) . Increase in Sea Surface Temperature (Decrease in dissolution) . Decrease in photosynthetic/primary organic matter production (Due to stratification) 0.6 Land 0.3 0.0 (%) 0.4 2 Ocean 0.3 CO Canadell et al. 2007, PNAS 0.2 1960 1970 1980 1990 2000 Source: Estimated emissions from fossil-fuel combustion and cement production of 9.1 Pg C, combined with the emissions from land-use change of 0.9 Pg C, led to a total emission of 10.0 Pg C in 2010 (Friedlingstein et al., 2010). Sink: Of the remainder of the total emissions (5.0 Pg C), the ocean sink is 2.4 Pg C, and the residual attributed to the land sink is 2.6 Pg C (Le Quéré, 2009) . Accumulation in the atmosphere: Half of the total emissions (5.0 Pg C) remains in the atmosphere, leading to one of the largest atmospheric growth rates in the past decade (2.36 ppm) and the concentration at the end of 2010 of 390 ppm of CO2 (Conway & Tans, 2011).
    [Show full text]
  • Changes in Ocean Circulation and Carbon Storage Are Decoupled from Air-Sea CO2 Fluxes
    Biogeosciences, 8, 505–513, 2011 www.biogeosciences.net/8/505/2011/ Biogeosciences doi:10.5194/bg-8-505-2011 © Author(s) 2011. CC Attribution 3.0 License. Changes in ocean circulation and carbon storage are decoupled from air-sea CO2 fluxes I. Marinov1,2 and A. Gnanadesikan3,4 1Department of Earth and Environmental Science, University of Pennsylvania, 240 S. 33rd Street, Hayden Hall 153, Philadelphia, PA 19104, USA 2Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, 266 Woods Hole Road, Woods Hole, MA 02543, USA 3Geophysical Fluid Dynamics Lab (NOAA), 201 Forrestal Road, Princeton, NJ 08540, USA 4Department of Earth and Planetary Sciences, Johns Hopkins Univ., Baltimore, MD, USA Received: 6 October 2010 – Published in Biogeosciences Discuss.: 1 November 2010 Revised: 28 January 2011 – Accepted: 7 February 2011 – Published: 25 February 2011 Abstract. The spatial distribution of the air-sea flux ing, we show that the air-sea CO2 flux is insensitive to the of carbon dioxide is a poor indicator of the underlying circulation, in contrast to the storage of carbon by the ocean. ocean circulation and of ocean carbon storage. The weak We analyze this contrasting behavior in terms of the dependence on circulation arises because mixing-driven oceanic solubility and biological pumps of carbon. Cold changes in solubility-driven and biologically-driven air-sea high latitude surface waters hold more dissolved inorganic fluxes largely cancel out. This cancellation occurs because carbon (DIC) than warm, low-latitude waters. The solubility mixing driven increases in the poleward residual mean circu- pump is the result of processes whereby these cold waters lation result in more transport of both remineralized nutrients sink, injecting CO2 into the deep ocean (Volk and Hoffert, and heat from low to high latitudes.
    [Show full text]
  • Ocean Uptake Potential for Carbon Dioxide Sequestration
    Geochemical Journal, Vol. 39, pp. 29 to 45, 2005 Ocean uptake potential for carbon dioxide sequestration MASAO SORAI* and TAKASHI OHSUMI** Research Institute of Innovative Technology for the Earth (RITE), 9-2 Kizugawadai, Kizu-cho, Soraku-gun, Kyoto 619-0292, Japan (Received June 26, 2003; Accepted May 7, 2004) For the assessment of the long-term consequences of the carbon dioxide ocean sequestration, the CO2 injection into the middle depth parts of the ocean was simulated using a geochemical box model of the global carbon cycle. The model consists of 19 reservoir boxes and includes all the essential processes in the global biogeochemical cycles, such as the ocean thermohaline circulation, the solubility pump, the biological pump, the alkalinity pump and the terrestrial ecosys- tem responses. The present study aims to reveal the effectiveness and consequences of the direct ocean CO2 sequestration P in relation to both lowering the atmospheric transient CO2 peak and reduction in future CO2 uptake potential of the ocean. We should note that the direct ocean injection of CO2 at the present time means the acceleration of the pH lowering in the middle ocean due to the eventual and inevitable increase of CO2 in the atmosphere, if the same amount of CO2 is added into the atmosphere-ocean system. The minimization of impact to the whole marine ecosystem might be attainable by the direct ocean CO2 sequestration through suppressing a decrease in the pH of the surface ocean rich in biota. The geochemical implication of the ocean sequestration is such that the maximum CO2 amount to invade into the ocean, i.e., the oceanic P CO2 uptake potential integrated with time until the end of fossil fuel era, is only dependent on the atmospheric CO2 value in the ultimate steady state, whether or not the CO2 is purposefully injected into the ocean; we gave the total potential P capacity of the ocean for the CO2 sequestration is about 1600 GtC in the case of atmospheric steady state value ( CO2 ) of 550 ppmv.
    [Show full text]
  • The Microbial Carbon Pump Concept: Potential Biogeochemical Significance in the Globally Changing Ocean Louis Legendre, Richard B
    The microbial carbon pump concept: Potential biogeochemical significance in the globally changing ocean Louis Legendre, Richard B. Rivkin, Markus Weinbauer, Lionel Guidi, Julia Uitz To cite this version: Louis Legendre, Richard B. Rivkin, Markus Weinbauer, Lionel Guidi, Julia Uitz. The microbial carbon pump concept: Potential biogeochemical significance in the globally changing ocean. Progress in Oceanography, Elsevier, 2015, 134, pp.432-450. 10.1016/j.pocean.2015.01.008. hal-01120262 HAL Id: hal-01120262 https://hal.sorbonne-universite.fr/hal-01120262 Submitted on 25 Feb 2015 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Review The microbial carbon pump concept: potential biogeochemical significance in the globally changing ocean POSSIBLE ALTERNATIVE TITLE The microbial carbon pump concept: potential biogeochemical significance in the context of the biological and carbonate pumps and in the globally changing ocean Louis Legendrea,b,*, Richard B. Rivkinc, Markus Weinbauera,b, Lionel Guidia,b, Julia Uitza,b a Sorbonne Universités, UPMC Univ. Paris 06, UMR 7093, Laboratoire d'Océanographie de Villefranche, 06230 Villefranche-sur-Mer, France b CNRS, UMR 7093, Laboratoire d'Océanographie de Villefranche, 06230 Villefranche-sur- Mer, France c Department of Ocean Sciences, Memorial University of Newfoundland, St.
    [Show full text]
  • Evaluating the Biological Pump Efficiency of the Last Glacial Maximum Ocean Using Δ13c Anne L
    https://doi.org/10.5194/cp-2020-7 Preprint. Discussion started: 14 February 2020 c Author(s) 2020. CC BY 4.0 License. Evaluating the Biological Pump Efficiency of the Last Glacial Maximum Ocean using δ13C Anne L. Morée1, Jörg Schwinger2, Ulysses S. Ninneman3, Aurich Jeltsch-Thömmes4, Ingo Bethke1, Christoph Heinze1 5 1Geophysical Institute, University of Bergen and Bjerknes Centre for Climate Research, Bergen, 5007, Norway 2NORCE Norwegian Research Centre and Bjerknes Centre for Climate Research, Bergen, 5838, Norway 3Department of Earth Science, University of Bergen and Bjerknes Centre for Climate Research, Bergen, 5007, Norway 4Climate and Environmental Physics, Physics Institute and Oeschger Centre for Climate Change Research, 10 University of Bern, Bern, Switzerland Correspondence to: Anne L. Morée ([email protected]) Abstract. Although both physical and biological marine changes are required to explain the 100 ppm lower atmospheric pCO2 of the Last Glacial Maximum (LGM, ~21 ka) as compared to pre-industrial (PI) times, their exact contributions are debated. Proxies of past marine carbon cycling (such as δ13C) document these changes, and 15 thus provide constraints for quantifying the drivers of long-term carbon cycle variability. This modelling study explores the relative roles of physical and biological changes in the ocean needed to simulate an LGM ocean in satisfactory agreement with proxy data, and here especially δ13C. We prepared a PI and LGM ocean model state (NorESM-OC) with full biogeochemistry (including the carbon isotopes δ13C and radiocarbon) and dynamic sea ice. The modelled LGM-PI differences are evaluated against a wide range of physical and biogeochemical proxy 20 data, and show agreement for key aspects of the physical ocean state within the data uncertainties.
    [Show full text]
  • Remote Sensing of the Northwest African Upwelling and Its Production
    Remote sensing of the Northwest African upwelling and its production dynamics Dissertation zur Erlangung des Doktorgrades der Naturwissenschaften am Fachbereich 5 – Geowissenschaften der Universität Bremen Gutachter: Herr Prof. Dr. Gerold Wefer Herr Prof. Dr. Venugopalan Ittekkot vorgelegt von Peer Helmke Bremen, Dezember 2003 Tag des Kolloquiums: 2 Februar 2004 Gutachter: Herr Prof. Dr. Gerold Wefer Herr Prof. Dr. Venugopalan Ittekkot Prüfer: Herr Prof. Dr. Helmut Willems Frau Prof. Dr. Katrin Huhn Inhaltsverzeichnis Abstract........................................................................................................................... 3 Zusammenfassung ......................................................................................................... 5 Introduction.................................................................................................................... 8 The global carbon cycle ......................................................................................... 8 Main objectives .................................................................................................... 10 Study area............................................................................................................. 12 Topography................................................................................................. 12 Wind-system ............................................................................................... 13 Oceanography ............................................................................................
    [Show full text]
  • Global Evaluation of Particulate Organic Carbon Parameterizations and Implications
    Global Evaluation of Particulate Organic Carbon Parameterizations and Implications for Atmospheric pCO2 Author: Supervisor: Lucas J. GLOEGE Dr. Galen MCKINLEY A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science (Atmospheric and Oceanic Sciences) at the University of Wisconsin - Madison 2017 Thesis Declaration and Approval I, Lucas J. GLOEGE, declare that this thesis titled, “Global Evaluation of Particulate Organic Carbon Parameterizations and Implications for Atmospheric pCO2” and the work presented in it are my own. Lucas J. Gloege, Signature Date I hereby approve and recommend for acceptance this work in partial fulfillment of the requirements for the degree of Master of Science: Galen A. McKinley, Signature Date Daniel J. Vimont, Signature Date Ankur R. Desai, Signature Date i Abstract Global Evaluation of Particulate Organic Carbon Parameterizations and Implications for Atmospheric pCO2 by Lucas J. GLOEGE under the supervision of Dr. Galen MCKINLEY This work is under review for publication in Global Biogeochemical Cycles The shunt of photosynthetically derived particulate organic carbon (POC) from the euphotic zone and deep remineralization comprises the basic mechanism of the ‘bi- ological carbon pump.’ POC raining through the ‘twilight zone’ (euphotic depth to 1 km) and ‘midnight zone ’(1 km to 4 km) is remineralized back to inorganic form through respiration. Accurately modeling POC flux is critical for understanding the ‘biological pump’ and its impacts on air-sea CO2 exchange and, ultimately, long- term ocean carbon sequestration. Yet, commonly used parameterizations have not been tested quantitatively against global datasets using identical modeling frame- works. Here, we use a single one-dimensional physical-biogeochemical modeling framework to assess three common POC flux parameterizations in capturing POC flux observations from moored sediment traps and thorium-234 depletion.
    [Show full text]
  • The Carbon Cycle and Climate Change/J Bret Bennington – First Edition ISBN 1 3: 978-0-495-73855-8;;, ISBN 1 0: 0-495-73855-7
    38557_00_cover.qxd 12/24/08 4:36 PM Page 1 The collection of chemical pathways by which carbon moves between Earth systems is called the carbon cycle and it is the flow of carbon through this cycle that ties together the functioning of the Earth’s atmosphere, biosphere, geosphere, and oceans to regulate the climate of our planet. This means that as drivers of planet Earth, anything we do to change the function or state of one Earth system will change the function and state of all Earth systems. If we change the composition of the atmosphere, we will also cause changes to propagate through the biosphere, hydrosphere, and geosphere, altering our planet in ways that will likely not be beneficial to human welfare. Understanding the functioning of the carbon cycle in detail so that we can predict the effects of human activities on the Earth and its climate is one of the most important scientific challenges of the 21st century. Package this module with any Cengage Learning text where learning about the car- bon cycle and humanity’s impact on the environment is important. About the Author Dr. J Bret Bennington grew up on Long Island and studied geology as an under- graduate at the University of Rochester in upstate New York. He earned his doctorate in Paleontology from the Department of Geological Sciences at Virginia Tech in 1995 and has been on the faculty of the Department of Geology at Hofstra University since 1993. Dr. Bennington’s research is focused on quantifying stability and change in marine benthic paleocommunities in the fossil record and on integrating paleontological and sedimentological data to understand the development of depositional sequences in both Carboniferous and Cretaceous marine environments.
    [Show full text]