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Constants of global biogeochemical ocean models are often tuned by hand to match observations of nutrients or oxygen. We investigate the effect of this tuning by optimising six constants of a global biogeochemical model, simulated in five different offline circulations. Optimal values for three constants adjust to distinct features of the circulation applied and can afterwards be swapped among the circulations, without losing too much of the model's fit to observed quantities.
Constants of global biogeochemical ocean models are often tuned by hand to match observations of...
BG | Articles | Volume 17, issue 12
Biogeosciences, 17, 3057–3082, 2020
https://doi.org/10.5194/bg-17-3057-2020
Research article 18 Jun 2020
Research article | 18 Jun 2020
One size fits all? Calibrating an ocean biogeochemistry model for different circulations
Iris Kriest et al.
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Zooplankton mortality effects on the plankton community of the Northern Humboldt Current System: Sensitivity of a regional biogeochemical model
Mariana Hill Cruz, Iris Kriest, Yonss Saranga José, Rainer Kiko, Helena Hauss, and Andreas Oschlies
Biogeosciences Discuss., https://doi.org/10.5194/bg-2020-417,https://doi.org/10.5194/bg-2020-417, 2020
Preprint under review for BG
In this study we use a regional biogeochemical model of the Eastern Tropical South Pacific Ocean to implicitly simulate the effect that fluctuations in populations of small pelagic fish, such as anchovy and sardine, may have on the biogeochemistry of the Northern Humboldt Current System. To do so, we vary the zooplankton mortality in the model, under the assumption that these fishes eat zooplankton. We also evaluate the model for the first time against mesozooplankton observations.
The effect of marine aggregate parameterisations on nutrients and oxygen minimum zones in a global biogeochemical model
Daniela Niemeyer, Iris Kriest, and Andreas Oschlies
Recent studies suggest spatial variations of the marine particle flux length scale. Using a global biogeochemical ocean model, we investigate whether changes in particle size and size-dependent sinking can explain this variation. We address uncertainties by varying aggregate properties and circulation. Both aspects have an impact on the representation of nutrients, oxygen and oxygen minimum zones. The formation and sinking of large aggregates in productive areas lead to deeper flux penetration.
Calibration of a simple and a complex model of global marine biogeochemistry
Iris Kriest
Early biogeochemical ocean models were of a simple structure, with few biogeochemical components. I here investigate whether additional biological complexity improves the fit with respect to observed global climatologies of annual mean nutrients and oxygen. After optimisation against these tracers a simple model fits observations almost as well as a more complex one, also with respect to independent estimates of global biogeochemical fluxes.
Evaluation of the transport matrix method for simulation of ocean biogeochemical tracers
Karin F. Kvale, Samar Khatiwala, Heiner Dietze, Iris Kriest, and Andreas Oschlies
Geosci. Model Dev., 10, 2425–2445, https://doi.org/10.5194/gmd-10-2425-2017,https://doi.org/10.5194/gmd-10-2425-2017, 2017
Computer models of ocean biology and chemistry are becoming increasingly complex, and thus more expensive, to run. One solution is to approximate the behaviour of the ocean physics and store that information outside of the model. That offline information can then be used to calculate a steady-state solution from the model's biology and chemistry, without waiting for a traditional online integration to complete. We show this offline method reproduces online results and is 100 times faster.
Reviews and syntheses: parameter identification in marine planktonic ecosystem modelling
Markus Schartau, Philip Wallhead, John Hemmings, Ulrike Löptien, Iris Kriest, Shubham Krishna, Ben A. Ward, Thomas Slawig, and Andreas Oschlies
Plankton models have become an integral part in marine ecosystem and biogeochemical research. These models differ in complexity and in their number of parameters. How values are assigned to parameters is essential. An overview of major methodologies of parameter estimation is provided. Aspects of parameter identification in the literature are diverse. Individual findings could be better synthesized if notation and expertise of the different scientific communities would be reasonably merged.
Calibrating a global three-dimensional biogeochemical ocean model (MOPS-1.0)
Iris Kriest, Volkmar Sauerland, Samar Khatiwala, Anand Srivastav, and Andreas Oschlies
Geosci. Model Dev., 10, 127–154, https://doi.org/10.5194/gmd-10-127-2017,https://doi.org/10.5194/gmd-10-127-2017, 2017
Global biogeochemical ocean models are subject to a high level of parametric uncertainty. This may be of consequence for their skill with respect to accurately describing features of the present ocean and their sensitivity to possible environmental changes. We present the first results from a framework that combines an offline biogeochemical tracer transport model with an estimation of distribution algorithm, calibrating six biogeochemical model parameters against observed oxygen and nutrients.
Evaluation of NorESM-OC (versions 1 and 1.2), the ocean carbon-cycle stand-alone configuration of the Norwegian Earth System Model (NorESM1)
Jörg Schwinger, Nadine Goris, Jerry F. Tjiputra, Iris Kriest, Mats Bentsen, Ingo Bethke, Mehmet Ilicak, Karen M. Assmann, and Christoph Heinze
Geosci. Model Dev., 9, 2589–2622, https://doi.org/10.5194/gmd-9-2589-2016,https://doi.org/10.5194/gmd-9-2589-2016, 2016
We present an evaluation of the ocean carbon cycle stand-alone configuration of the Norwegian Earth System Model. A re-tuning of the ecosystem parameterisation improves surface tracer fields between versions 1 and 1.2 of the model. Focus is placed on the evaluation of newly implemented parameterisations of the biological carbon pump (i.e. the sinking of particular organic carbon). We find that the model previously underestimated the carbon transport into the deep ocean below 2000 m depth.
MOPS-1.0: towards a model for the regulation of the global oceanic nitrogen budget by marine biogeochemical processes
I. Kriest and A. Oschlies
We use a global model of oceanic P, N, and O2 cycles to investigate consequences of uncertainties in description of organic matter sinking, remineralization, denitrification, and N2-Fixation. After all biogeochemical and physical processes have been spun-up into a dynamically consistent steady-state, particle sinking and oxidant affinities of aerobic and anaerobic remineralization determine the extent of oxygen minimum zones, global nitrogen fluxes, and the oceanic nitrogen inventory.
Swept under the carpet: organic matter burial decreases global ocean biogeochemical model sensitivity to remineralization length scale
A novel estimate of ocean oxygen utilisation points to a reduced rate of respiration in the ocean interior
O. Duteil, W. Koeve, A. Oschlies, D. Bianchi, E. Galbraith, I. Kriest, and R. Matear
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Optimality-based non-Redfield plankton–ecosystem model (OPEM v1.1) in UVic-ESCM 2.9 – Part 2: Sensitivity analysis and model calibration
Chia-Te Chien, Markus Pahlow, Markus Schartau, and Andreas Oschlies
We demonstrate sensitivities of tracers to parameters of a new optimality-based plankton–ecosystem model (OPEM) in the UVic-ESCM. We find that changes in phytoplankton subsistence nitrogen quota strongly impact the nitrogen inventory, nitrogen fixation, and elemental stoichiometry of ordinary phytoplankton and diazotrophs. We introduce a new likelihood-based metric for model calibration, and it shows the capability of constraining globally averaged oxygen, nitrate, and DIC concentrations.
Optimality-based non-Redfield plankton–ecosystem model (OPEM v1.1) in UVic-ESCM 2.9 – Part 1: Implementation and model behaviour
Markus Pahlow, Chia-Te Chien, Lionel A. Arteaga, and Andreas Oschlies
The stoichiometry of marine biotic processes is important for the regulation of atmospheric CO2 and hence the global climate. We replace a simplistic, fixed-stoichiometry plankton module in an Earth system model with an optimal-regulation model with variable stoichiometry. Our model compares better to the observed carbon transfer from the surface to depth and surface nutrient distributions. This work could aid our ability to describe and project the role of marine ecosystems in the Earth system.
Evaluation of the University of Victoria Earth System Climate Model version 2.10 (UVic ESCM 2.10)
Nadine Mengis, David P. Keller, Andrew H. MacDougall, Michael Eby, Nesha Wright, Katrin J. Meissner, Andreas Oschlies, Andreas Schmittner, Alexander J. MacIsaac, H. Damon Matthews, and Kirsten Zickfeld
In this paper, we evaluate the newest version of the University of Victoria Earth System Climate Model (UVic ESCM 2.10). Combining recent model developments as a joint effort, this version is to be used in the next phase of model intercomparison and climate change studies. The UVic ESCM 2.10 is capable of reproducing changes in historical temperature and carbon fluxes well. Additionally, the model is able to reproduce the three-dimensional distribution of many ocean tracers.
Explicit silicate cycling in the Kiel Marine Biogeochemistry Model, version 3 (KMBM3) embedded in the UVic ESCM version 2.9
Karin Kvale, David P. Keller, Wolfgang Koeve, Katrin J. Meissner, Chris Somes, Wanxuan Yao, and Andreas Oschlies
Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2020-235,https://doi.org/10.5194/gmd-2020-235, 2020
Revised manuscript under review for GMD
We present a new model of biological marine silicate cycling for the University of Victoria Earth System Climate Model (UVic ESCM). This new model adds diatoms, which are a key aspect of the biological carbon pump, to an existing ecosystem model. Our modifications change how the model responds to warming, with net primary production declining more strongly than in previous versions. Diatoms in particular are simulated to decline with climate warming due to their high nutrient requirements.
Reanalysis of vertical mixing in mesocosm experiments: PeECE III and KOSMOS 2013
Sabine Mathesius, Julia Getzlaff, Heiner Dietze, Andreas Oschlies, and Markus Schartau
Earth Syst. Sci. Data, 12, 1775–1787, https://doi.org/10.5194/essd-12-1775-2020,https://doi.org/10.5194/essd-12-1775-2020, 2020
Controlled manipulation of environmental conditions within large enclosures in the ocean, pelagic mesocosms, has become a standard method to explore responses of marine plankton communities to anthropogenic change. Among the challenges of interpreting mesocosm data is the often uncertain role of vertical mixing. This study introduces a mesocosm mixing model that is able to estimate vertical diffusivities and thus provides a tool for future mesocosm data analyses that account for mixing.
The fate of upwelled nitrate off Peru shaped by submesoscale filaments and fronts
Jaard Hauschildt, Soeren Thomsen, Vincent Echevin, Andreas Oschlies, Yonss Saranga José, Gerd Krahmann, Laura A. Bristow, and Gaute Lavik
In this paper we quantify the subduction of upwelled nitrate due to physical processes on the order of several kilometers in the coastal upwelling off Peru and its effect on primary production. We also compare the prepresentation of these processes in a high-resolution simulation (~2.5 km) with a more coarsely resolved simulation (~12 km). To do this, we combine high-resolution shipboard observations of physical and biogeochemical parameters with a complex biogeochemical model configuration.
Meeting climate targets by direct CO2 injections: what price would the ocean have to pay?
Fabian Reith, Wolfgang Koeve, David P. Keller, Julia Getzlaff, and Andreas Oschlies
Earth Syst. Dynam., 10, 711–727, https://doi.org/10.5194/esd-10-711-2019,https://doi.org/10.5194/esd-10-711-2019, 2019
This modeling study is the first one to look at the suitability and collateral effects of direct CO2 injection into the deep ocean as a means to bridge the gap between CO2 emissions and climate impacts of an intermediate CO2 emission scenario and a temperature target on a millennium timescale, such as the 1.5 °C climate target of the Paris Agreement.
Ocean phosphorus inventory: large uncertainties in future projections on millennial timescales and their consequences for ocean deoxygenation
Tronje P. Kemena, Angela Landolfi, Andreas Oschlies, Klaus Wallmann, and Andrew W. Dale
Oceanic deoxygenation is driven by climate change in several areas of the global ocean. Measurements indicate that ocean volumes with very low oxygen levels expand, with consequences for marine organisms and fishery. We found climate-change-driven phosphorus (P) input in the ocean is hereby an important driver for deoxygenation on longer timescales with effects in the next millennia.
ENSO-driven fluctuations in oxygen supply and vertical extent of oxygen-poor waters in the oxygen minimum zone of the Eastern Tropical South Pacific
Yonss Saranga José, Lothar Stramma, Sunke Schmidtko, and Andreas Oschlies
Revised manuscript accepted for BG
In situ observations along the Peruvian and Chilean coasts have exhibited variability in the water column oxygen concentration. This variability, which is attributed to the El Niño Southern Oscillation (ENSO), might have implication on the vertical extension of the Eastern Tropical South Pacific (ETSP) oxygen minimum zone. Here using a coupled physical-biogeochemical model, we provide new insights into how ENSO variability affects the vertical extension of the oxygen-poor waters of the ETSP.
Phytoplankton calcifiers control nitrate cycling and the pace of transition in warming icehouse and cooling greenhouse climates
Karin F. Kvale, Katherine E. Turner, Angela Landolfi, and Katrin J. Meissner
Drivers motivating the evolution of calcifying phytoplankton are poorly understood. We explore differences in global ocean chemistry with and without calcifiers during rapid climate changes. We find the presence of phytoplankton calcifiers stabilizes the volume of low oxygen regions and consequently stabilizes the concentration of nitrate, which is an important nutrient required for photosynthesis. By stabilizing nitrate concentrations, calcifiers improve their growth conditions.
Pacific Decadal Oscillation and recent oxygen decline in the eastern tropical Pacific Ocean
Olaf Duteil, Andreas Oschlies, and Claus W. Böning
Oxygen-depleted regions of the Pacific Ocean are currently expanding, which is threatening marine habitats. Based on numerical simulations, we show that the decrease in the intensity of the trade winds and the subsequent slowdown of the oceanic currents lead to a reduction in oxygen supply. Our study suggests that the prevailing positive conditions of the Pacific Decadal Oscillation since 1975, a major source of natural variability, may explain a significant part of the current deoxygenation.
Modulation of the vertical particle transfer efficiency in the oxygen minimum zone off Peru
Marine Bretagnon, Aurélien Paulmier, Véronique Garçon, Boris Dewitte, Séréna Illig, Nathalie Leblond, Laurent Coppola, Fernando Campos, Federico Velazco, Christos Panagiotopoulos, Andreas Oschlies, J. Martin Hernandez-Ayon, Helmut Maske, Oscar Vergara, Ivonne Montes, Philippe Martinez, Edgardo Carrasco, Jacques Grelet, Olivier Desprez-De-Gesincourt, Christophe Maes, and Lionel Scouarnec
In oxygen minimum zone, the fate of the organic matter is a key question as the low oxygen condition would preserve the OM and thus enhance the biological carbon pump while the high microbial activity would foster the remineralisation and the greenhouse gases emission. To investigate this paradigm, sediment traps were deployed off Peru. We pointed out the influence of the oxygenation as well as the organic matter quantity and quality on the carbon transfer efficiency in the oxygen minimum zone.
Error assessment of biogeochemical models by lower bound methods (NOMMA-1.0)
Volkmar Sauerland, Ulrike Löptien, Claudine Leonhard, Andreas Oschlies, and Anand Srivastav
We present a concept to prove that a parametric model is well calibrated, i.e., that changes of its free parameters cannot lead to a much better model–data misfit anymore. The intention is motivated by the fact that calibrating global biogeochemical ocean models is important for assessment and inter-model comparison but computationally expensive.
Systematic Correlation Matrix Evaluation (SCoMaE) – a bottom–up, science-led approach to identifying indicators
Nadine Mengis, David P. Keller, and Andreas Oschlies
Earth Syst. Dynam., 9, 15–31, https://doi.org/10.5194/esd-9-15-2018,https://doi.org/10.5194/esd-9-15-2018, 2018
The Systematic Correlation Matrix Evaluation (SCoMaE) method applies statistical information to systematically select, transparent, nonredundant indicators for a comprehensive assessment of the Earth system state. We show that due to changing climate forcing, such as anthropogenic climate change, the ad hoc assessment indicators might need to be reevaluated. Within an iterative process, this method would allow us to select scientifically consistent and societally relevant assessment indicators.
Primary production sensitivity to phytoplankton light attenuation parameter increases with transient forcing
Karin F. Kvale and Katrin J. Meissner
Climate models containing ocean biogeochemistry contain a lot of poorly constrained parameters, which makes model tuning difficult. For more than 20 years modellers have generally assumed phytoplankton light attenuation parameter value choice has an insignificant affect on model ocean primary production; thus, it is often overlooked for tuning. We show that an empirical range of light attenuation parameter values can affect primary production, with increasing sensitivity under climate change.
Biogeochemical protocols and diagnostics for the CMIP6 Ocean Model Intercomparison Project (OMIP)
James C. Orr, Raymond G. Najjar, Olivier Aumont, Laurent Bopp, John L. Bullister, Gokhan Danabasoglu, Scott C. Doney, John P. Dunne, Jean-Claude Dutay, Heather Graven, Stephen M. Griffies, Jasmin G. John, Fortunat Joos, Ingeborg Levin, Keith Lindsay, Richard J. Matear, Galen A. McKinley, Anne Mouchet, Andreas Oschlies, Anastasia Romanou, Reiner Schlitzer, Alessandro Tagliabue, Toste Tanhua, and Andrew Yool
The Ocean Model Intercomparison Project (OMIP) is a model comparison effort under Phase 6 of the Coupled Model Intercomparison Project (CMIP6). Its physical component is described elsewhere in this special issue. Here we describe its ocean biogeochemical component (OMIP-BGC), detailing simulation protocols and analysis diagnostics. Simulations focus on ocean carbon, other biogeochemical tracers, air-sea exchange of CO2 and related gases, and chemical tracers used to evaluate modeled circulation.
A model study of warming-induced phosphorus–oxygen feedbacks in open-ocean oxygen minimum zones on millennial timescales
Daniela Niemeyer, Tronje P. Kemena, Katrin J. Meissner, and Andreas Oschlies
Earth Syst. Dynam., 8, 357–367, https://doi.org/10.5194/esd-8-357-2017,https://doi.org/10.5194/esd-8-357-2017, 2017
Linking diverse nutrient patterns to different water masses within anticyclonic eddies in the upwelling system off Peru
Yonss Saranga José, Heiner Dietze, and Andreas Oschlies
This study aims to investigate the diverse subsurface nutrient patterns observed within anticyclonic eddies in the upwelling system off Peru. Two simulated anticyclonic eddies with opposing subsurface nitrate concentrations were analysed. The results show that diverse nutrient patterns within anticyclonic eddies are related to the presence of water mass from different origins at different depths, responding to variations in depth of the circulation strength at the edge of the eddy.
Revisiting ocean carbon sequestration by direct injection: a global carbon budget perspective
Fabian Reith, David P. Keller, and Andreas Oschlies
Box-modelling of the impacts of atmospheric nitrogen deposition and benthic remineralisation on the nitrogen cycle of the eastern tropical South Pacific
Bei Su, Markus Pahlow, and Andreas Oschlies
Previously identified positive feedbacks within the nitrogen cycle in the eastern tropical South Pacific (ETSP) have challenged our understanding of the observed dynamics and stability of the nitrogen inventory. We present a box model analysis of the biological and biogeochemical relations in the ETSP among nitrogen deposition, benthic denitrification and phosphate regeneration. Our results suggest dominant stabilizing feedbacks tending to keep a balanced nitrogen inventory in the ETSP.
14C-age tracers in global ocean circulation models
W. Koeve, H. Wagner, P. Kähler, and A. Oschlies
The natural abundance of 14C in CO2 dissolved in seawater is often used to evaluate circulation and age in the ocean and in ocean models. We study limitations of using natural 14C to determine the time elapsed since water had contact with the atmosphere. We find that, globally, bulk 14C age is dominated by two equally important components, (1) the time component of circulation and (2) the "preformed 14C-age". Considering preformed 14C-age is critical for an assessment of circulation in models.
A dynamic marine iron cycle module coupled to the University of Victoria Earth System Model: the Kiel Marine Biogeochemical Model 2 for UVic 2.9
L. Nickelsen, D. P. Keller, and A. Oschlies
In this paper we find that including the marine cycle of the phytoplankton nutrient iron in a global climate model improves the agreement between observed and simulated nutrient concentrations in the ocean and that a better description of the source of iron from the sediment to the ocean is more important than that of iron-containing dust deposition. Finally, we find that the response of the iron cycle to climate warming affects the phytoplankton growth and nutrient cycles.
What prevents nitrogen depletion in the oxygen minimum zone of the eastern tropical South Pacific?
B. Su, M. Pahlow, H. Wagner, and A. Oschlies
A box model of the eastern tropical South Pacific oxygen minimum zone suggests that anaerobic water-column remineralization rates have to be slower than aerobic remineralization in order to explain the relatively high values of observed nitrate concentrations. Lateral oxygen supply sufficient to oxidize about one-fifth of the export production is required to prevent an anoxic deep ocean. Under these circumstances, the region can be a net source of fixed nitrogen to the surrounding ocean.
Methods to evaluate CaCO3 cycle modules in coupled global biogeochemical ocean models
W. Koeve, O. Duteil, A. Oschlies, P. Kähler, and J. Segschneider
How important is diversity for capturing environmental-change responses in ecosystem models?
A. E. F. Prowe, M. Pahlow, S. Dutkiewicz, and A. Oschlies
Explicit planktic calcifiers in the University of Victoria Earth System Climate Model
K. F. Kvale, K. J. Meissner, D. P. Keller, M. Eby, and A. Schmittner
Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmdd-7-1709-2014,https://doi.org/10.5194/gmdd-7-1709-2014, 2014
Revised manuscript not accepted
Isotopic constraints on the pre-industrial oceanic nitrogen budget
C. J. Somes, A. Oschlies, and A. Schmittner
Oxygen and indicators of stress for marine life in multi-model global warming projections
V. Cocco, F. Joos, M. Steinacher, T. L. Frölicher, L. Bopp, J. Dunne, M. Gehlen, C. Heinze, J. Orr, A. Oschlies, B. Schneider, J. Segschneider, and J. Tjiputra
Overlooked runaway feedback in the marine nitrogen cycle: the vicious cycle
A. Landolfi, H. Dietze, W. Koeve, and A. Oschlies
Reducing the model-data misfit in a marine ecosystem model using periodic parameters and linear quadratic optimal control
M. El Jarbi, J. Rückelt, T. Slawig, and A. Oschlies
Nitrous oxide dynamics in low oxygen regions of the Pacific: insights from the MEMENTO database
L. M. Zamora, A. Oschlies, H. W. Bange, K. B. Huebert, J. D. Craig, A. Kock, and C. R. Löscher
Biogeosciences, 9, 5007–5022, https://doi.org/10.5194/bg-9-5007-2012,https://doi.org/10.5194/bg-9-5007-2012, 2012
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Use of optical absorption indices to assess seasonal variability of dissolved organic matter in Amazon floodplain lakes
Maria Paula da Silva, Lino A. Sander de Carvalho, Evlyn Novo, Daniel S. F. Jorge, and Claudio C. F. Barbosa
In this study, we analyze the seasonal changes in the dissolved organic matter (DOM) quality (based on its optical properties) in four Amazon floodplain lakes. DOM plays a fundamental role in surface water chemistry, controlling metal bioavailability and mobility, and nutrient cycling. The model proposed in our paper highlights the potential to study DOM quality at a wider spatial scale, which may help to better understand the persistence and fate of DOM in the ecosystem.
The role of sediment-induced light attenuation on primary production during Hurricane Gustav (2008)
Zhengchen Zang, Z. George Xue, Kehui Xu, Samuel J. Bentley, Qin Chen, Eurico J. D'Sa, Le Zhang, and Yanda Ou
Quantifying spatiotemporal variability in zooplankton dynamics in the Gulf of Mexico with a physical–biogeochemical model
Taylor A. Shropshire, Steven L. Morey, Eric P. Chassignet, Alexandra Bozec, Victoria J. Coles, Michael R. Landry, Rasmus Swalethorp, Glenn Zapfe, and Michael R. Stukel
Zooplankton are the smallest animals in the ocean and important food for fish. Despite their importance, zooplankton have been relatively undersampled. To better understand the zooplankton community in the Gulf of Mexico (GoM), we developed a model to simulate their dynamics. We found that heterotrophic protists are important for supporting mesozooplankton, which are the primary prey of larval fish. The model developed in this study has the potential to improve fisheries management in the GoM.
Assessing the temporal scale of deep-sea mining impacts on sediment biogeochemistry
Laura Haffert, Matthias Haeckel, Henko de Stigter, and Felix Janssen
Deep-sea mining for polymetallic nodules is expected to have severe environmental impacts. Through prognostic modelling, this study aims to provide a holistic assessment of the biogeochemical recovery after a disturbance event. It was found that the recovery strongly depends on the impact type; e.g. complete removal of the surface sediment reduces seafloor nutrient fluxes over centuries.
Unique role of jellyfish in the plankton ecosystem revealed using a global ocean biogeochemical model
Rebecca Mary Wright, Corinne Le Quéré, Erik Buitenhuis, Sophie Pitois, and Mark Gibbons
Jellyfish have been included in a global ocean biogeochemical model for the first time. The replication of global mean jellyfish biomass is within the observational range. Jellyfish exert control over the other zooplankton, with the greatest influence on macrozooplankton, and though trophic cascades influence the phytoplankton. The model raises questions about the sensitivity of the zooplankton community to jellyfish mortality and the interactions between macrozooplankton and jellyfish.
Seasonal patterns of surface inorganic carbon system variables in the Gulf of Mexico inferred from a regional high-resolution ocean biogeochemical model
Fabian A. Gomez, Rik Wanninkhof, Leticia Barbero, Sang-Ki Lee, and Frank J. Hernandez Jr.
We use a numerical model to infer annual changes of surface carbon chemistry in the Gulf of Mexico (GoM). The main seasonality drivers of partial pressure of carbon dioxide and aragonite saturation state from the model are temperature and river runoff. The GoM basin is a carbon sink in winter–spring and carbon source in summer–fall, but uptake prevails near the Mississippi Delta year-round due to high biological production. Our model results show good correspondence with observational studies.
Oxygen dynamics and evaluation of the single-station diel oxygen model across contrasting geologies
Simon J. Parker
Biogeosciences, 17, 305–315, https://doi.org/10.5194/bg-17-305-2020,https://doi.org/10.5194/bg-17-305-2020, 2020
Dissolved oxygen (DO) models typically assume constant ecosystem respiration over the course of a single day. Using a data-driven approach, this research examines this assumption in four streams across two (hydro-)geological types (Chalk and Greensand). Despite hydrogeological equivalence in terms of baseflow index for each hydrogeological pairing, model suitability differed within, rather than across, geology types. This corresponded with associated differences in timings of DO minima.
Oceanic CO2 outgassing and biological production hotspots induced by pre-industrial river loads of nutrients and carbon in a global modeling approach
Fabrice Lacroix, Tatiana Ilyina, and Jens Hartmann
Biogeosciences, 17, 55–88, https://doi.org/10.5194/bg-17-55-2020,https://doi.org/10.5194/bg-17-55-2020, 2020
Contributions of rivers to the oceanic cycling of carbon have been poorly represented in global models until now. Here, we assess the long–term implications of preindustrial riverine loads in the ocean in a novel framework which estimates the loads through a hierarchy of weathering and land–ocean export models. We investigate their impacts for the oceanic biological production and air–sea carbon flux. Finally, we assess the potential incorporation of the framework in an Earth system model.
Global trends in marine nitrate N isotopes from observations and a neural network-based climatology
Patrick A. Rafter, Aaron Bagnell, Dario Marconi, and Timothy DeVries
The N isotopic composition of nitrate ( nitrate δ15N ) is a useful tracer of ocean N cycling and many other ocean processes. Here, we use a global compilation of marine nitrate δ15N as an input, training, and validating dataset for an artificial neural network (a.k.a., machine learning ) and examine basin-scale trends in marine nitrate δ15N from the surface to the seafloor.
Merging bio-optical data from Biogeochemical-Argo floats and models in marine biogeochemistry
Elena Terzić, Paolo Lazzari, Emanuele Organelli, Cosimo Solidoro, Stefano Salon, Fabrizio D'Ortenzio, and Pascal Conan
Measuring ecosystem properties in the ocean is a hard business. Recent availability of data from Biogeochemical-Argo floats can help make this task easier. Numerical models can integrate these new data in a coherent picture and can be used to investigate the functioning of ecosystem processes. Our new approach merges experimental information and model capabilities to quantitatively demonstrate the importance of light and water vertical mixing for algae dynamics in the Mediterranean Sea.
Model constraints on the anthropogenic carbon budget of the Arctic Ocean
Jens Terhaar, James C. Orr, Marion Gehlen, Christian Ethé, and Laurent Bopp
A budget of anthropogenic carbon in the Arctic Ocean, the main driver of open-ocean acidification, was constructed for the first time using a high-resolution ocean model. The budget reveals that anthropogenic carbon enters the Arctic Ocean mainly by lateral transport; the air–sea flux plays a minor role. Coarser-resolution versions of the same model, typical of earth system models, store less anthropogenic carbon in the Arctic Ocean and thus underestimate ocean acidification in the Arctic Ocean.
Modeling oceanic nitrate and nitrite concentrations and isotopes using a 3-D inverse N cycle model
Taylor S. Martin, François Primeau, and Karen L. Casciotti
Nitrite is a key intermediate in many nitrogen (N) cycling processes in the ocean, particularly in areas with low oxygen that are hotspots for N loss. We have created a 3-D global N cycle model with nitrite as a tracer. Stable isotopes of N are also included in the model and we are able to model the isotope fractionation associated with each N cycling process. Our model accurately represents N concentrations and isotope distributions in the ocean.
Biogeochemical response of the Mediterranean Sea to the transient SRES-A2 climate change scenario
Camille Richon, Jean-Claude Dutay, Laurent Bopp, Briac Le Vu, James C. Orr, Samuel Somot, and François Dulac
We evaluate the effects of climate change and biogeochemical forcing evolution on the nutrient and plankton cycles of the Mediterranean Sea for the first time. We use a high-resolution coupled physical and biogeochemical model and perform 120-year transient simulations. The results indicate that changes in external nutrient fluxes and climate change may have synergistic or antagonistic effects on nutrient concentrations, depending on the region and the scenario.
Modelling the biogeochemical effects of heterotrophic and autotrophic N2 fixation in the Gulf of Aqaba (Israel), Red Sea
Angela M. Kuhn, Katja Fennel, and Ilana Berman-Frank
Recent studies demonstrate that marine N2 fixation can be carried out without light. However, direct measurements of N2 fixation in dark environments are relatively scarce. This study uses a model that represents biogeochemical cycles at a deep-ocean location in the Gulf of Aqaba (Red Sea). Different model versions are used to test assumptions about N2 fixers. Relaxing light limitation for marine N2 fixers improved the similarity between model results and observations of deep nitrate and oxygen.
A perturbed biogeochemistry model ensemble evaluated against in situ and satellite observations
Prima Anugerahanti, Shovonlal Roy, and Keith Haines
Minor changes in the biogeochemical model equations lead to major dynamical changes. We assessed this structural sensitivity for the MEDUSA biogeochemical model on chlorophyll and nitrogen concentrations at five oceanographic stations over 10 years, using 1-D ensembles generated by combining different process equations. The ensemble performed better than the default model in most of the stations, suggesting that our approach is useful for generating a probabilistic biogeochemical ensemble model.
Diazotrophy as the main driver of the oligotrophy gradient in the western tropical South Pacific Ocean: results from a one-dimensional biogeochemical–physical coupled model
Audrey Gimenez, Melika Baklouti, Thibaut Wagener, and Thierry Moutin
During the OUTPACE cruise conducted in the oligotrophic to ultra-oligotrophic region of the western tropical South Pacific, two contrasted regions were sampled in terms of N2 fixation rates, primary production rates and nutrient availability. The aim of this work was to investigate the role of N2 fixation in the differences observed between the two contrasted areas by comparing two simulations only differing by the presence or not of N2 fixers using a 1-D biogeochemical–physical coupled model.
Causes of simulated long-term changes in phytoplankton biomass in the Baltic proper: a wavelet analysis
Jenny Hieronymus, Kari Eilola, Magnus Hieronymus, H. E. Markus Meier, Sofia Saraiva, and Bengt Karlson
This paper investigates how phytoplankton concentrations in the Baltic Sea co-vary with nutrient concentrations and other key variables on inter-annual timescales in a model integration over the years 1850–2008. The study area is not only affected by climate change; it has also been subjected to greatly increased nutrient loads due to extensive use of agricultural fertilizers. The results indicate the largest inter-annual coherence of phytoplankton with the limiting nutrient.
Modelling N2 fixation related to Trichodesmium sp.: driving processes and impacts on primary production in the tropical Pacific Ocean
Cyril Dutheil, Olivier Aumont, Thomas Gorguès, Anne Lorrain, Sophie Bonnet, Martine Rodier, Cécile Dupouy, Takuhei Shiozaki, and Christophe Menkes
N2 fixation is recognized as one of the major sources of nitrogen in the ocean. Thus, N2 fixation sustains a significant part of the primary production (PP) by supplying the most common limiting nutrient for phytoplankton growth. From numerical simulations, the local maximums of Trichodesmium biomass in the Pacific are found around islands, explained by the iron fluxes from island sediments. We assessed that 15 % of the PP may be due to Trichodesmium in the low-nutrient, low-chlorophyll areas.
Long-term response of oceanic carbon uptake to global warming via physical and biological pumps
Akitomo Yamamoto, Ayako Abe-Ouchi, and Yasuhiro Yamanaka
Millennial-scale changes in oceanic CO2 uptake due to global warming are simulated by a GCM and offline biogeochemical model. Sensitivity studies show that decreases in oceanic CO2 uptake are mainly caused by a weaker biological pump and seawater warming. Enhanced CO2 uptake due to weaker equatorial upwelling cancels out reduced CO2 uptake due to weaker AMOC and AABW formation. Thus, circulation change plays only a small direct role in reduction of CO2 uptake due to global warming.
Seasonal patterns in phytoplankton biomass across the northern and deep Gulf of Mexico: a numerical model study
Fabian A. Gomez, Sang-Ki Lee, Yanyun Liu, Frank J. Hernandez Jr., Frank E. Muller-Karger, and John T. Lamkin
Seasonal patterns in nanophytoplankton and diatom biomass in the Gulf of Mexico were examined with an ocean–biogeochemical model. We found silica limitation of model diatom growth in the deep GoM and Mississippi delta. Zooplankton grazing and both transport and vertical mixing of biomass substantially influence the model phytoplankton biomass seasonality. We stress the need for integrated analyses of biologically and physically driven biomass fluxes to describe phytoplankton seasonal changes.
Sea-surface dimethylsulfide (DMS) concentration from satellite data at global and regional scales
Martí Galí, Maurice Levasseur, Emmanuel Devred, Rafel Simó, and Marcel Babin
We developed a new algorithm to estimate the sea-surface concentration of dimethylsulfide (DMS) using satellite data. DMS is a gas produced by marine plankton that, once emitted to the atmosphere, plays a key climatic role by seeding cloud formation. We used the algorithm to produce global DMS maps and also regional DMS time series. The latter suggest that DMS can vary largely from one year to another, which should be taken into account in atmospheric studies.
A new look at the multi-G model for organic carbon degradation in surface marine sediments for coupled benthic–pelagic simulations of the global ocean
Konstantin Stolpovsky, Andrew W. Dale, and Klaus Wallmann
The paper describes a new way to parameterize G-type models in marine sediments using data about reactivity of organic carbon sinking to the seafloor.
Groundwater data improve modelling of headwater stream CO2 outgassing with a stable DIC isotope approach
Anne Marx, Marcus Conrad, Vadym Aizinger, Alexander Prechtel, Robert van Geldern, and Johannes A. C. Barth
CO2 outgassing from small streams causes one of the main uncertainties in global carbon budgets. These are caused by variable flow conditions, changing stream surface areas, and groundwater seeps. Here we used groundwater data to improve a novel stable carbon isotope modelling approach. We found that CO2 outgassing contributed more than three-fourths of annual stream inorganic carbon loss in a small, silicate catchment. We underline the potential of this approach for global applications.
The influence of the ocean circulation state on ocean carbon storage and CO2 drawdown potential in an Earth system model
Malin Ödalen, Jonas Nycander, Kevin I. C. Oliver, Laurent Brodeau, and Andy Ridgwell
We conclude that different initial states for an ocean model result in different capacities for ocean carbon storage due to differences in the ocean circulation state and the origin of the carbon in the initial ocean carbon reservoir. This could explain why it is difficult to achieve comparable responses of the ocean carbon system in model inter-comparison studies in which the initial states vary between models. We show that this effect of the initial state is quantifiable.
Modelling potential production of macroalgae farms in UK and Dutch coastal waters
Johan van der Molen, Piet Ruardij, Karen Mooney, Philip Kerrison, Nessa E. O'Connor, Emma Gorman, Klaas Timmermans, Serena Wright, Maeve Kelly, Adam D. Hughes, and Elisa Capuzzo
Macroalgae farming may provide biofuel. Modelled macroalgae production is given for four sites in UK and Dutch waters. Macroalgae growth depended on nutrient concentrations and light levels. Macroalgae carbohydrate content, important for biofuel use, was lower for high nutrient concentrations. The hypothetical large-scale farm off the UK north Norfolk coast gave high, stable yields of macroalgae from year to year with substantial carbohydrate content.
Assimilating bio-optical glider data during a phytoplankton bloom in the southern Ross Sea
Daniel E. Kaufman, Marjorie A. M. Friedrichs, John C. P. Hemmings, and Walker O. Smith Jr.
Computer simulations of the highly variable phytoplankton in the Ross Sea demonstrated how incorporating data from different sources (satellite, ship, or glider) results in different system interpretations. For example, simulations assimilating satellite-based data produced lower carbon export estimates. Combining observations with models in this remote, harsh, and biologically variable environment should include consideration of the potential impacts of data frequency, duration, and coverage.
On the long-range offshore transport of organic carbon from the Canary Upwelling System to the open North Atlantic
Elisa Lovecchio, Nicolas Gruber, Matthias Münnich, and Zouhair Lachkar
We find that a big portion of the phytoplankton, zooplankton, and detrital organic matter produced near the northern African coast is laterally transported towards the open North Atlantic. This offshore flux sustains a relevant part of the biological activity in the open sea and reaches as far as the middle of the North Atlantic. Our results, obtained with a state-of-the-art model, highlight the fundamental role of the narrow but productive coastal ocean in sustaining global marine life.
Improving the inverse modeling of a trace isotope: how precisely can radium-228 fluxes toward the ocean and submarine groundwater discharge be estimated?
Guillaume Le Gland, Laurent Mémery, Olivier Aumont, and Laure Resplandy
In this study, we computed the fluxes of radium-228 from the continental shelf to the open ocean by fitting a numerical model to observations. After determining appropriate model parameters (cost function and number of source regions), we found a lower and more precise global flux than previous estimates: 8.01–8.49×1023 atoms yr−1. This result can be used to assess nutrient and trace element fluxes to the open ocean, but we cannot identify specific pathways like submarine groundwater discharge.
Implications of sea-ice biogeochemistry for oceanic production and emissions of dimethyl sulfide in the Arctic
Hakase Hayashida, Nadja Steiner, Adam Monahan, Virginie Galindo, Martine Lizotte, and Maurice Levasseur
In remote regions, cloud conditions may be strongly influenced by oceanic source of dimethylsulfide (DMS) produced by plankton and bacteria. In the Arctic, sea ice provides an additional source of these aerosols. The results of this study highlight the importance of taking into account both the sea-ice sulfur cycle and ecosystem in the flux estimates of oceanic DMS near the ice margins and identify key uncertainties in processes and rates that would be better constrained by new observations.
A numerical analysis of biogeochemical controls with physical modulation on hypoxia during summer in the Pearl River estuary
Bin Wang, Jiatang Hu, Shiyu Li, and Dehong Liu
We proposed a novel method named the physical modulation method to quantify the contributions of boundary conditions, the source and sink processes occurring in local and adjacent waters to DO conditions. A mass balance analysis of DO based on the physical modulation method indicated that the DO conditions were mainly controlled by source and sink processes, among which the sediment oxygen demand and re-aeration were two main processes controlling the spatial extent and the duration of hypoxia.
Potential sources of variability in mesocosm experiments on the response of phytoplankton to ocean acidification
Maria Moreno de Castro, Markus Schartau, and Kai Wirtz
Observations from different mesocosms exposed to the same treatment level typically show variability that hinders the detection of potential treatments effects. To unearth relevant sources of variability, we developed and performed a data-based model analysis that simulates uncertainty propagation. With this method we investigate the divergence in the outcomes due to the amplification of differences in experimentally unresolved ecological factors within replicates of the same treatment level.
A data–model synthesis to explain variability in calcification observed during a CO2 perturbation mesocosm experiment
Shubham Krishna and Markus Schartau
This study combines experimental data with results from numerical modelling. Data of an ocean acidification mesocosm experiment are used to constrain parameter values of a plankton model. Three different intensities of calcification are resolved with ensembles of optimised model results. Observed variability in data can be well explained by these ensemble model solutions. The simulated ocean acidification effect on calcification is small compared to the spread of the ensemble model solutions.
Manganese in the west Atlantic Ocean in the context of the first global ocean circulation model of manganese
Marco van Hulten, Rob Middag, Jean-Claude Dutay, Hein de Baar, Matthieu Roy-Barman, Marion Gehlen, Alessandro Tagliabue, and Andreas Sterl
We ran a global ocean model to understand manganese (Mn), a biologically essential element. Our model shows that (i) in the deep ocean, dissolved [Mn] is mostly homogeneous ~0.10—0.15 nM. The model reproduces this with a threshold on MnO2 of 25 pM, suggesting a minimal particle concentration is needed before aggregation and removal become efficient. (ii) The observed distinct hydrothermal signals are produced by assuming both a strong source and a strong removal of Mn near hydrothermal vents.
Growth of the coccolithophore Emiliania huxleyi in light- and nutrient-limited batch reactors: relevance for the BIOSOPE deep ecological niche of coccolithophores
Laura Perrin, Ian Probert, Gerald Langer, and Giovanni Aloisi
Coccolithophores are calcifying marine algae that play an important role in the oceanic carbon cycle. Deep niches of coccolithophores exist in the ocean and are poorly understood. Laboratory cultures with the coccolithophore Emiliania huxleyi were carried out to reproduce the environmental conditions (light–nutrient limitation) of a deep niche in the South Pacific Ocean. Physiological modelling of experimental results allows us to estimate the growth rates of coccolithophores in this niche.
Biogeochemical fluxes and fate of diazotroph-derived nitrogen in the food web after a phosphate enrichment: modeling of the VAHINE mesocosms experiment
Audrey Gimenez, Melika Baklouti, Sophie Bonnet, and Thierry Moutin
In the context of the VAHINE mesocosm experiment in the Nouméa lagoon (New Caledonia), a 1-D vertical biogeochemical mechanistic model was used together with the in situ experiment to complement our comprehension of the planktonic ecosystem dynamics and the main biogeochemical carbon, nitrogen and phosphate fluxes. The model also showed the fate of fixed N2 by providing, over time, the proportion of diazotroph-derived nitrogen (DDN) in each compartment (mineral and organic) of the model.
Marine regime shifts in ocean biogeochemical models: a case study in the Gulf of Alaska
Claudie Beaulieu, Harriet Cole, Stephanie Henson, Andrew Yool, Thomas R. Anderson, Lee de Mora, Erik T. Buitenhuis, Momme Butenschön, Ian J. Totterdell, and J. Icarus Allen
Regime shifts have been suggested in the late 1970s and late 1980s in the Gulf of Alaska with important consequences for fisheries. Here we investigate the ability of a suite of ocean biogeochemical models of varying complexity to simulate these regime shifts. Our results demonstrate that ocean models can successfully simulate regime shifts in the Gulf of Alaska region, thereby improving our understanding of how changes in physical conditions are propagated from lower to upper trophic levels.
Modeling pCO2 variability in the Gulf of Mexico
Zuo Xue, Ruoying He, Katja Fennel, Wei-Jun Cai, Steven Lohrenz, Wei-Jen Huang, Hanqin Tian, Wei Ren, and Zhengchen Zang
In this study we used a state-of-the-science coupled physical–biogeochemical model to simulate and examine temporal and spatial variability of sea surface CO2 concentration in the Gulf of Mexico. Our model revealed the Gulf was a net CO2 sink with a flux of 1.11 ± 0.84 × 1012 mol C yr−1. We also found that biological uptake was the primary driver making the Gulf an overall CO2 sink and that the carbon flux in the northern Gulf was very susceptible to changes in river inputs.
Seasonal variability of the oxygen minimum zone off Peru in a high-resolution regional coupled model
Oscar Vergara, Boris Dewitte, Ivonne Montes, Veronique Garçon, Marcel Ramos, Aurélien Paulmier, and Oscar Pizarro
The Southeast Pacific hosts one of the most extensive oxygen minimum zone (OMZ), yet the dynamics behind it remain unveiled. We use a high-resolution coupled physical–biogeochemical model to document the seasonal cycle of dissolved oxygen within the OMZ in both the coastal zone and the offshore ocean. The OMZ seasonal variability is driven by the seasonal fluctuations of the dissolved oxygen eddy flux, with a peak in Austral winter (fall) at the northern (southern) boundary and near the coast.
Ocean acidification over the next three centuries using a simple global climate carbon-cycle model: projections and sensitivities
Corinne A. Hartin, Benjamin Bond-Lamberty, Pralit Patel, and Anupriya Mundra
Methane and sulfate dynamics in sediments from mangrove-dominated tropical coastal lagoons, Yucatán, Mexico
Pei-Chuan Chuang, Megan B. Young, Andrew W. Dale, Laurence G. Miller, Jorge A. Herrera-Silveira, and Adina Paytan
A transport-reaction model was used to simulate porewater methane and sulfate concentrations. Model results and sediment slurry incubation experiments show high methane production rates supported by non-competitive substrates and ample dissolved and labile organic matter as well as methane from deeper sediment through bubbles dissolution and diffusion. The shallow methane production and accumulation depths in these sediments promote high methane fluxes to the water column and atmosphere.
Transfer of radiocaesium from contaminated bottom sediments to marine organisms through benthic food chains in post-Fukushima and post-Chernobyl periods
Roman Bezhenar, Kyung Tae Jung, Vladimir Maderich, Stefan Willemsen, Govert de With, and Fangli Qiao
Measurements after the Fukushima Dai-ichi accident show that elevated concentrations of Cs-137 still remain in sediments, benthic organisms, and demersal fishes in the coastal zone. The dynamic food chain model has been extended to include benthic organisms. We showed that the gradual decrease of activity in the demersal fish after the accident was caused by the transfer of activity from organic matter deposited on the bottom through the deposit-feeding invertebrates.
A probabilistic assessment of calcium carbonate export and dissolution in the modern ocean
Gianna Battaglia, Marco Steinacher, and Fortunat Joos
The marine cycle of calcium carbonate (CaCO3) influences the distribution of CO2 between atmosphere and ocean, and thereby climate. We constrain export of biogenic CaCO3 (globally: 0.72–1.05 Gt C yr−1) and dissolution within the water column (~ 80 %) in a novel Monte Carlo set-up with the Bern3D model based on alkalinity data. Whether CaCO3 dissolves in the upper ocean remains unresolved. We recommend using constant (saturation-independent) dissolution rates in Earth system models.
Potential environmental impact of tidal energy extraction in the Pentland Firth at large spatial scales: results of a biogeochemical model
Johan van der Molen, Piet Ruardij, and Naomi Greenwood
The potential large-scale (> 100 km) effects of marine renewable tidal energy generation in the Pentland Firth were studied using a 3-D hydrodynamics–biogeochemistry model. A realistic 800 MW scenario suggested minor effects on tides and biogeochemistry. A massive-expansion 8 GW scenario suggested effects over hundreds of kilometres away with changes of up to 10 % in tidal and ecosystem variables, the latter through clearer waters and increased primary production with associated increases in fauna.
Challenges in modeling spatiotemporally varying phytoplankton blooms in the Northwestern Arabian Sea and Gulf of Oman
S. Sedigh Marvasti, A. Gnanadesikan, A. A. Bidokhti, J. P. Dunne, and S. Ghader
This study examines challenges in modeling phytoplankton blooms in Northwestern Arabian Sea and Gulf of Oman. Blooms in the region show strong modulation both by seasons and in the wintertime by eddies. However getting both of these correct is a challenge in a set of state-of-the-art global Earth System models. It is argued that maintaining a sharp pycnocline may be the key for preventing the wintertime bloom from being too strong and for allowing eddies to modulate upward mixing of nutrients.
Parameterization of biogeochemical sediment–water fluxes using in situ measurements and a diagenetic model
A. Laurent, K. Fennel, R. Wilson, J. Lehrter, and R. Devereux
In low oxygen environments, the lack of oxygen influences sediment biogeochemistry and in turn sediment-water fluxes. These nonlinear interactions are often missing from biogeochemical circulation models because sediment models are computationally expensive. A method for parameterizing realistic sediment-water fluxes is presented and applied to the Mississippi River Dead Zone where high primary production, stimulated by excess nutrient loads, promotes low bottom water conditions in summer.
A latitudinally banded phytoplankton response to 21st century climate change in the Southern Ocean across the CMIP5 model suite
S. Leung, A. Cabré, and I. Marinov
Using the latest earth system models, we find that shifts in nutrient and light availability with future climate warming drive latitudinally banded changes in Southern Ocean phytoplankton distributions, which have the potential to significantly alter nutrient cycling as well as higher trophic level productivity throughout the global ocean. Spatial patterns in the modelled mechanisms driving these predicted phytoplankton trends qualitatively agree with recent observations.
The mechanisms of North Atlantic CO2 uptake in a large Earth System Model ensemble
P. R. Halloran, B. B. B. Booth, C. D. Jones, F. H. Lambert, D. J. McNeall, I. J. Totterdell, and C. Völker
The oceans currently take up around a quarter of the carbon dioxide (CO2) emitted by human activity. While stored in the ocean, this CO2 is not causing global warming. Here we explore high latitude North Atlantic CO2 uptake across a set of climate model simulations, and find that the models show a peak in ocean CO2 uptake around the middle of the century after which time CO2 uptake begins to decline. We identify the causes of this long-term change and interannual variability in the models.
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Kriest, I.: Model code and data set, available at: https://data.geomar.de/thredds/catalog/open_access/kriest_et_al_2020_bg/catalog.html, last access: 6 February 2020. a
Kriest, I. and Oschlies, A.: On the treatment of particulate organic matter sinking in large-scale models of marine biogeochemical cycles, Biogeosciences, 5, 55–72, https://doi.org/10.5194/bg-5-55-2008, 2008. a
Kriest, I. and Oschlies, A.: Numerical effects on organic-matter sedimentation and remineralization in biogeochemical ocean models, Ocean Model., 39, 275–283, https://doi.org/10.1016/j.ocemod.2011.05.001, 2011. a
Kriest, I. and Oschlies, A.: MOPS-1.0: towards a model for the regulation of the global oceanic nitrogen budget by marine biogeochemical processes, Geosci. Model Dev., 8, 2929–2957, https://doi.org/10.5194/gmd-8-2929-2015, 2015. a, b, c, d, e, f, g, h, i, j
Kriest, I., Oschlies, A., and Khatiwala, S.: Sensitivity analysis of simple global marine biogeochemical models, Global Biogeochem. Cy., 26, GB2029, https://doi.org/10.1029/2011GB004072, 2012. a, b, c, d, e, f, g, h
Kriest, I., Sauerland, V., Khatiwala, S., Srivastav, A., and Oschlies, A.: Calibrating a global three-dimensional biogeochemical ocean model (MOPS-1.0), Geosci. Model Dev., 10, 127–154, https://doi.org/10.5194/gmd-10-127-2017, 2017. a, b, c, d, e, f, g, h, i, j
Kvale, K. F., Khatiwala, S., Dietze, H., Kriest, I., and Oschlies, A.: Evaluation of the transport matrix method for simulation of ocean biogeochemical tracers, Geosci. Model Dev., 10, 2425–2445, https://doi.org/10.5194/gmd-10-2425-2017, 2017. a, b, c
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Kwon, E. Y., Primeau, F., and Sarmiento, J.: The impact of remineralization depth on the air-sea carbon balance, Nat. Geosci., 2, 630–635, https://doi.org/10.1038/NGEO612, 2009. a, b, c, d, e
Letscher, R. T., Moore, J. K., Teng, Y.-C., and Primeau, F.: Variable C : N : P stoichiometry of dissolved organic matter cycling in the Community Earth System Model, Biogeosciences, 12, 209–221, https://doi.org/10.5194/bg-12-209-2015, 2015. a
Li, X. and Primeau, F.: A fast Newton–Krylov solver for seasonally varying global ocean biogeochemistry models, Ocean Model., 23, 13–20, https://doi.org/10.1016/j.ocemod.2008.03.001, 2008. a
Löptien, U. and Dietze, H.: Reciprocal bias compensation and ensuing uncertainties in model-based climate projections: pelagic biogeochemistry versus ocean mixing, Biogeosciences, 16, 1865–1881, https://doi.org/10.5194/bg-16-1865-2019, 2019. a, b, c
Lutz, M., Caldeira, K., Dunbar, R., and Behrenfeld, M. J.: Seasonal rhythms of net primary production and particulate organic carbon flux to depth describe biological pump efficiency in the global ocean, J. Geophys. Res., 113, C10011, https://doi.org/10.1029/2006JC003706, 2007. a
Marconi, D., Sigman, D. M., Casciotti, K., Campbell, E., Weigand, M., Fawcett, S., Knapp, A., Rafter, P., Ward, B., and Haug, G.: Tropical Dominance of N2 Fixation in the North Atlantic Ocean, Global Biogeochem. Cy., 31, 1608–1623, https://doi.org/10.1002/2016GB005613, 2017. a
Marsay, C. M., Sanders, R., Henson, S., Pabortsava, K., Achterberg, E., and Lampitt, R.: Attenuation of sinking particulate organic carbon flux through the mesopelagic ocean, P. Natl. Acad. Sci. USA, 112, 1089–1094, https://doi.org/10.1073/pnas.1415311112, 2015. a
Marshall, J., Adcroft, A., Hill, C., Perelman, L., and Heisey, C.: A finite-volume, incompressible Navier–Stokes model for studies of the ocean on parallel computers, J. Geophys. Res., 102, 5733–5752, https://doi.org/10.1029/96JC02775, 1997. a
Matsumoto, K., Sarmiento, J. L., Key, R. M., Aumont, O., Bullister, J. L., Caldeira, K., Campin, J., Doney, S. C., Drange, H., Dutay, J., Follows, M., Gao, Y., Gnanadesikan, A., Gruber, N., Ishida, A., Joos, F., Lindsay, K., Maier-Reimer, E., Marshall, J. C., Matear, R. J., Monfray, P., Mouchet, A., Najjar, R., Plattner, G., Schlitzer, R., Slater, R., Swathi, P. S., Totterdell, I. J., Weirig, M., Yamanaka, Y., Yool, A., and Orr, J. C.: Evaluation of ocean carbon cycle models with data-based metrics, Geophys. Res. Lett., 31, L07303, https://doi.org/10.1029/2003GL018970, 2004. a
Najjar, R. G., Jin, X., Louanchi, F., Aumont, O., Caldeira, K., Doney, S. C., Dutay, J.-C., Follows, M., Gruber, N., Joos, F., Lindsay, K., Maier-Reimer, E., Matear, R., Matsumoto, K., Monfray, P., Mouchet, A., Orr, J. C., Plattner, G.-K., Sarmiento, J. L., Schlitzer, R., Slater, R. D., Weirig, M.-F., Yamanaka, Y., and Yool, A.: Impact of circulation on export production, dissolved organic matter and dissolved oxygen in the ocean: Results from Phase II of the Ocean Carbon-cycle Model Intercomparison Project (OCMIP-2), Global Biogeochem. Cy., 21, GB3007, https://doi.org/10.1029/2006GB002857, 2007. a, b, c, d, e, f, g, h, i, j, k
Niemeyer, D., Kriest, I., and Oschlies, A.: The effect of marine aggregate parameterisations on nutrients and oxygen minimum zones in a global biogeochemical model, Biogeosciences, 16, 3095–3111, https://doi.org/10.5194/bg-16-3095-2019, 2019. a
Palter, J. B., Sarmiento, J. L., Gnanadesikan, A., Simeon, J., and Slater, R. D.: Fueling export production: nutrient return pathways from the deep ocean and their dependence on the Meridional Overturning Circulation, Biogeosciences, 7, 3549–3568, https://doi.org/10.5194/bg-7-3549-2010, 2010. a, b, c
Paulmier, A., Kriest, I., and Oschlies, A.: Stoichiometries of remineralisation and denitrification in global biogeochemical ocean models, Biogeosciences, 6, 923–935, https://doi.org/10.5194/bg-6-923-2009, 2009. a, b
Primeau, F. and Deleersnijder, E.: On the time to tracer equilibrium in the global ocean, Ocean Sci., 5, 13–28, https://doi.org/10.5194/os-5-13-2009, 2009. a
Rafter, P., DiFiore, P., and Sigman, D.: Coupled nitrate nitrogen and oxygen isotopes and organic matter remineralization in the Southern and Pacific Oceans, J. Geophys. Res., 118, 4781–4794, https://doi.org/10.1002/jgrc.20316, 2013. a, b
Rafter, P. A., Sigman, D. M., Charles, C. D., Kaiser, J., and Haug, G. H.: Subsurface tropical Pacific nitrogen isotopic composition of nitrate: Biogeochemical signals and their transport, Global Biogeochem. Cy., 26, GB1003, https://doi.org/10.1029/2010GB003979, 2012. a
Sallee, J.-B., Speer, K., Rintoul, S., and Wijfels, S.: Southern Ocean thermocline ventilation, J. Phys. Oceanogr., 40, 509–529, https://doi.org/10.1175/2009JPO4291.1, 2010. a
Sallee, J.-B., Shuckburgh, E., Bruneau, N., Meijers, A. J. S., Bracegirdle, T. J., and Wang, Z.: Assessment of Southern Ocean mixed-layer depths in CMIP5 models: Historical bias and forcing response, J. Geophys. Res., 118, 1845–1862, https://doi.org/10.1002/jgrc.20157, 2013. a, b, c, d, e
Sauerland, V., Kriest, I., Oschlies, A., and Srivastav, A.: Multiobjective Calibration of a Global Biogeochemical Ocean Model Against Nutrients, Oxygen, and Oxygen Minimum Zones, J. Adv. Model. Earth Sy., 11, 1285–1308, https://doi.org/10.1029/2018MS001510, 2019. a, b, c, d
Schmittner, A., Oschlies, A., Giraud, X., Eby, M., and Simmons, H. L.: A global model of the marine ecosystem for long-term simulations: Sensitivity to ocean mixing, buoyancy forcing, particle sinking, and dissolved organic matter cycling, Global Biogeochem. Cy., 19, GB3004, https://doi.org/10.1029/2004GB002283, 2005. a, b, c, d, e, f, g, h
Schwinger, J., Goris, N., Tjiputra, J. F., Kriest, I., Bentsen, M., Bethke, I., Ilicak, M., Assmann, K. M., and Heinze, C.: Evaluation of NorESM-OC (versions 1 and 1.2), the ocean carbon-cycle stand-alone configuration of the Norwegian Earth System Model (NorESM1), Geosci. Model Dev., 9, 2589–2622, https://doi.org/10.5194/gmd-9-2589-2016, 2016. a
Séférian, R., Bopp, L., Gehlen, M., Orr, J., Ethe, C., Cadule, P., Aumont, O., Salas y Melia, D., Voldoire, A., and Madec, G.: Skill assessment of three earth system models with common marine biogeochemistry, Clim. Dynam., 40, 2549–2573, https://doi.org/10.1007/s00382-012-1362-8, 2013. a, b, c, d, e, f
Séférian, R., Gehlen, M., Bopp, L., Resplandy, L., Orr, J. C., Marti, O., Dunne, J. P., Christian, J. R., Doney, S. C., Ilyina, T., Lindsay, K., Halloran, P. R., Heinze, C., Segschneider, J., Tjiputra, J., Aumont, O., and Romanou, A.: Inconsistent strategies to spin up models in CMIP5: implications for ocean biogeochemical model performance assessment, Geosci. Model Dev., 9, 1827–1851, https://doi.org/10.5194/gmd-9-1827-2016, 2016. a
Somes, C. J., Oschlies, A., and Schmittner, A.: Isotopic constraints on the pre-industrial oceanic nitrogen budget, Biogeosciences, 10, 5889–5910, https://doi.org/10.5194/bg-10-5889-2013, 2013. a, b, c, d, e, f
Stammer, D., Ueyoshi, K., Köhl, A., Large, W. G., Josey, S. A., and Wunsch, C.: Estimating air-sea fluxes of heat, freshwater, and momentum through global ocean data assimilation, J. Geophys. Res., 109, C05023, https://doi.org/10.1029/2003JC002082, 2004. a
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Tuerena, R. E., Ganeshram, R. S., Geibert, W., Fallick, A. E., Dougans, J., Tait, A., Henley, S. F., and Woodward, E. M. S.: Nutrient cycling in the Atlantic basin: The evolution of nitrate isotope signatures in water masses, Global Biogeochem. Cy., 29, 1830–1844, https://doi.org/10.1002/2015GB005164, 2015. a, b, c
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Weaver, A., Eby, M., Wiebe, E., Bitz, C., Duffy, P., Ewen, T., Fanning, A., Holland, M., MacFadyen, A., Matthews, H., Meissner, K., Saenko, O., Schmittner, A., Wang, H., and Yoshimori, M.: The UVic Earth System Climate Model: Model description, climatology, and applications to past, present and future climates, Atmos. Ocean, 39, 361–428, https://doi.org/10.1080/07055900.2001.9649686, 2001. a, b
Weber, T., Cram, J., Leung, S., DeVries, T., and Deutsch, C.: Deep ocean nutrients imply large latitudinal variation in particle transfer efficiency, P. Natl. Acad. Sci USA., 113, 8606–8611, https://doi.org/10.1073/pnas.1604414113, 2016. a
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CHARLOTTE, NC — This year marks the City of Charlotte's 250th anniversary and to help mark the occasion, our community is coming together to celebrate Charlotte.
Adam Rhew with Charlotte Center City Partners stopped by Rising to talk about how you can get involved.
Click here to find out what CLT250 is all about.


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Olesya Rulin Net Worth
How much is Olesya Rulin worth?
Mar 17, 1986 (34 years old)
4 ft 11 in (1.52 m)
Actor, Ballet Dancer, Model
Olesya Rulin Net Worth:
More about the earnings of Olesya Rulin
Actor Olesya Rulin has a networth that has to be considered decent.
Olesya Rulin Net Worth: Olesya Rulin is a Russian actress who has a net worth of $1 million. Olesya Rulin was born in Moscow, Russia in March 1986. Rulin is best known for her role as Kelsi Nielsen in the High School Musical films franchise. Rulin and her family moved to the United States when she was eight years old. She is a trained ballet dancer who won a model search contest at 12 years old. She worked as a certified nursing assistant and at Nordstrom and Victoria's Secret. Her first acting roles came in the 2001 TV movies Hounded and The Poof Point. She appeared in the TV series Touched by an Angel and Everwood. She starred in the 2004 TV movie Halloweentown High and appeared in the video Urban legends: Blood Mary. Rulin starred in the 2005 movie Mobsters and Mormons. In 2006 she first played the role of Kelsi Nielsen in the TV movie High School Musical. She reprised the role for the TV movie High School Musical 2 in 2007 and the film High School Musical 3: Senior Year in 2008. From 2009 to 2011 Rulin had a recurring role as Abby in the TV series Greek. She has also starred in the movies American Pastime, The Dance, Forever Strong, Major Movie Star, Private Valentine: Blonde & Dangerous, Flying By, Expecting Mary, Apart, A Thousand Cuts, and Family Weekend.
Looking great Olesya Rulin: Who knew that such a high net worth lurked behind the facade
Inspirational Quotes by Olesya Rulin
I was really blessed with parents who never said I couldn't do anything. And now I reflect as an adult on that, 'Wow, they never told me no!'
Olesya Rulin
I was in a commercial for the Disney channel. I was the camp leader for the campers.
I've been to London twice. I saw the Broadway show 'Billy Elliot' there – phenomenal. I was crying through the entire thing.
I've had a lot of seedy side jobs. I've done it all. I've worked retail at the mall, just tons of side jobs, which I think are amazing for actors. I think everyone should have one! It helps you get more experiences, and the more experiences you have, the more you can channel into a character.
I attempt to surf. I'm not as good as anyone else in the water. I'm more like a beached whale. I just hang out on my board. I can ride, but I get too nervous unless I go with my boyfriend or my trainer. There are too many burly men out there!
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redpajama_set_name: RedPajamaCommonCrawl


The Wampaslayer podcast is back with Kris and Dave bringing the nerd news you want. Two of the new Star Trek series* are being renewed for season two and Sony pictures made money this year! Also, we jump into the weekend's Blizzcon announcements and a recap of the Overwatch World Cup.


With a diamond dobby texture, this yarn-dyed 100% cotton shirt has a refined look that stays crisp without ironing. Free from wrinkles and soft, it features single-needle tailoring, adjustable notched cuffs and Red House engraved buttons and embroidery on the right sleeve placket. Hidden button-down collar, notched patch pocket and back yoke with center pleat.


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Wed 26 April 2017
Cumbria joins MillionPlus to celebrate the #25andRising campaign
The University of Cumbria is supporting #25andRising, a campaign launched last month by the Association for Modern Universities to highlight what modern universities, and their students, have achieved over the past 25 years, and what more they have to offer.
This evening (Tues 25 April) an event to be held in the State Rooms at Speaker's House, hosted by the Speaker, The Rt Hon John Bercow MP, will give Parliamentarians the chance to meet with staff and students from modern universities.
A delegation from the University of Cumbria, including the university's Pro-Vice Chancellor Sandra Booth and Farhat Ibrahim, principal lecturer primary education based at the university's East India Dock Road campus, will join colleagues from across the country.
The reception will mark the 25th anniversary of the Further and Higher Education Acts 1992, legislation which provided higher education institutions which were already teaching undergraduate and postgraduate students the opportunity to apply for taught and research degree awarding powers and university title on the same basis as the universities which had already been established.
Twenty five years on, the UK's modern universities are internationally recognised, highly successful and educate over one million undergraduate and postgraduate students each year. They comprise around half of the UK's higher education sector, and have contributed significantly to its strengths, successes and reputation at home and abroad.
In addition to teaching, more than half of all modern university research is now judged as world-leading with over 60% judged to have outstanding impact in terms of its reach and significance.
Modern universities have led the development of degrees and apprenticeships to meet the needs of new and emerging industries and the graduate professions required by the UK in the 21st century. For instance: 77% of Social Work students; 72% of Nursing students; 68% of Medical Technology students; and more than a third of Engineering students study at a modern university.
"The passing of the Further and Higher Education Acts in 1992 transformed higher education in the UK in a deeply profound way, expanding opportunities for all," Professor Dave Phoenix, Chair of MillionPlus and Vice-Chancellor of London South Bank University, said. "Today the graduates of modern universities make up 72% of all graduate start-ups still active after three years and the fabric of our society reaps untold benefits from the entrepreneurs, scientists, engineers, teachers, nurses, designers and computer programmers, among many others, who have studied at these institutions. Modern universities are vital civic hubs in their local communities, bringing expertise, connections, ingenuity, translational research and the jobs and students from home and overseas which provide a vital boost to local economies."
Follow the campaign on the MillionPlus website and on Twitter, using the hashtag #25andRising


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Philippines' president under fire for saying...
In his latest remarks, President Duterte recounts a confession he had with a priest in high school.
'Stronger, faster' Pacquiao turns 40 with...
A car, pickup trucks and appliances were raffled off and President Rodrigo Duterte and celebrities were among the well-wishers at the all-night event,...
Philippine mayor on Duterte's 'narco list'...
Watchdogs have expressed concern Duterte's narcotics crackdown may be emboldening assailants.
Philippines' Duterte calls UN rights chief...
"Hey son of a whore, you commissioner, I need to go to a psychiatrist?" asked Duterte in a speech late Tuesday.
Duterte: Mass murderer in power
That's what Filipinos love him for (last year he had a 91 percent approval rating), but the problem is that he really is a tough guy - and not in a good...
Philippines moves to quit ICC: What does...
The ICC announced on February 9 a preliminary examination into allegations Philippine police have killed thousands of alleged users or dealers as part...
More than 100 killed since Philippine police...
Duterte was elected in 2016 on a promise to eradicate drugs, and launched an unprecedented campaign in which -- rights activists allege -- as many as 12,000...
'I fear for my life': Philippine lawyer behind...
"I'm in a state of constant paranoia because I fear for my life," Sabio, 51, told AFP in an interview. "It could be very possible that a bullet will hit...
'Happy' to kill: Philippine leader's views...
Amnesty International, Human Rights Watch and the European Union have all criticised the controversial leader for his bombastic statements appearing to...
Duterte under fire as Philippines moves to...
Duterte vowed last year to expose Rappler's "American ownership", while suggesting the US Central Intelligence Agency funded the outfit.
Justice at a price in Wakiso and...
Our undercover investigation has revealed how suspects pay to acquire justice in these courts.
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The New Vision


The staircases are the areas which witness maximum footfalls in the house. Carpeting the staircase not only adds to the aesthetic appeal of the house but also provides comfort from the hard surface of the stairs. There are some methods which need to be followed to the letter for installing carpet stairs.
The first step is to measure the dimensions of the stairs such as length, breadth and the height. The number of stairs also needs to be counted since it will determine the number of tackles strips and pads one would require for the carpet. Now the next step is to consult a carpet professional to discuss the project such as the size of the stairs, design and choice of the carpet. Photographs of the staircase also help the professional in giving sound advice to the customer.
Taking the creative side of the carpet into account is also important because these carpets are mainly decorating items. The different types of carpets possess different kinds of designs, hence it is imperative to lend as much as visible symmetry to the carpet as possible.
Purchasing the supplies such as the amount of carpet required for the stairs (extra couple of feet for accounting of possible cuts and errors), Tackles strips to hold the carpet and the padding, staples, hammer and nails, chisel and carpet knee kicker.
The tackles strips are then cut, 1.5 inches less than the width of the carpet. They are hammered into place through nails. Two strips per step. A horizontal strip is hammered to the height of each step and another set of strips are stuck on the other side of each step. The carpet pad is now cut and placed for each tread and the padding sheets are placed over the tackles strips and stapled.
The padding is pulled over the stair nosing and stapled every three inches. The carpet runner is then placed, ideally from top to bottom. The carpet runner should be between the outlines marked previously by a pencil. A carpet knee kicker will get the carpet fixed into the outline of the steps. The tackles strips should hold onto the carpet firmly, if not then a chisel can be used to press the angle between the step's height and tread to ensure that it gets hooked in. Finally the excess carpet should be cut off.
There are many varieties of carpet stairs available in many designs and sizes at both online and conventional stores. Every kind of design can be checked out through the internet.


With Super 78's proprietary Geppetto technology, animated characters become a part of our world, and we become of part of theirs. Guests get to have real, unscripted, one-on-one conversations with these fanciful creations. They can even take control of the story; in the SpongeBob SubPants Adventure guests tell Patrick where to navigate the sub next.
Geppetto-powered experiences are entertaining for all ages; for youngest guests, they are simply miraculous.
What was once the product of countless hours of work and hundreds of drawings is now available with a few clicks of a controller. Using custom software, the only of its kind, Geppetto allows a puppeteer to instantly bring a character to life, in real-time, in front of a live audience. Programmed with a system designed for ease of use, Geppetto's animated characters are designed with a variety of prerecorded movements that form the foundation for a living, breathing, fully believable animated character.
Geppetto is also a state-of-the-art production tool.
Super 78 developed this interactive Smurfs attraction for the new Motiongate Theme Park in Dubai. In this anchor experience for the park's Smurfs Village section, guests get to speak live and one-on-one with Brainy Smurf, and meet dozens of the famous blue characters.
The show features all the family-friendly humor and personality that have made The Smurfs beloved worldwide. Using sophisticated digital animation techniques, the Smurf characters are rendered as fully dimensional "performers" that remain true to the original drawings by creator Peyo.
Super 78 developed and produced a media-based Interactive Character attraction showcasing the world famous animated character Donkey from the Shrek franchise that sings, dances and interacts with a live audience.