scholarly journals Enhancing ocean biogeochemical model performance and generality with phytoplankton variable composition

2020 ◽  
Author(s):  
Prima Anugerahanti ◽  
Onur Kerimoglu ◽  
S. Lan Smith
Keyword(s):  
Model Performance ◽  
Variable Composition ◽  
Biogeochemical Model ◽  
Ocean Biogeochemical Model

EXPLORING CONTROLS ON THE MARINE BARIUM CYCLE USING A SPATIALLY RESOLVED OCEAN BIOGEOCHEMICAL MODEL

2020 ◽  
Author(s):  
Samantha Carter ◽  
◽  
Elizabeth M. Griffith ◽  
Arne Winguth ◽  
Teresa Beaty
Keyword(s):  
Biogeochemical Model ◽  
Spatially Resolved ◽  
Ocean Biogeochemical Model

scholarly journals Inconsistent strategies to spin up models in CMIP5: implications for ocean biogeochemical model performance assessment

2016 ◽  
Vol 9 (5) ◽  
pp. 1827-1851 ◽  
Author(s):  
Roland Séférian ◽  
Marion Gehlen ◽  
Laurent Bopp ◽  
Laure Resplandy ◽  
James C. Orr ◽  
...  
Keyword(s):  
Performance Assessment ◽  
Initial Conditions ◽  
Model Performance ◽  
Cmip5 Models ◽  
Biogeochemical Model ◽  
Earth System ◽  
Model Intercomparison ◽  
System Models ◽  
Marine Biogeochemistry ◽  
Earth System Models

Abstract. During the fifth phase of the Coupled Model Intercomparison Project (CMIP5) substantial efforts were made to systematically assess the skill of Earth system models. One goal was to check how realistically representative marine biogeochemical tracer distributions could be reproduced by models. In routine assessments model historical hindcasts were compared with available modern biogeochemical observations. However, these assessments considered neither how close modeled biogeochemical reservoirs were to equilibrium nor the sensitivity of model performance to initial conditions or to the spin-up protocols. Here, we explore how the large diversity in spin-up protocols used for marine biogeochemistry in CMIP5 Earth system models (ESMs) contributes to model-to-model differences in the simulated fields. We take advantage of a 500-year spin-up simulation of IPSL-CM5A-LR to quantify the influence of the spin-up protocol on model ability to reproduce relevant data fields. Amplification of biases in selected biogeochemical fields (O2, NO3, Alk-DIC) is assessed as a function of spin-up duration. We demonstrate that a relationship between spin-up duration and assessment metrics emerges from our model results and holds when confronted with a larger ensemble of CMIP5 models. This shows that drift has implications for performance assessment in addition to possibly aliasing estimates of climate change impact. Our study suggests that differences in spin-up protocols could explain a substantial part of model disparities, constituting a source of model-to-model uncertainty. This requires more attention in future model intercomparison exercises in order to provide quantitatively more correct ESM results on marine biogeochemistry and carbon cycle feedbacks.

scholarly journals Wind-driven changes in the ocean carbon sink

2014 ◽  
Vol 11 (21) ◽  
pp. 6107-6117 ◽  
Author(s):  
N. C. Swart ◽  
J. C. Fyfe ◽  
O. A. Saenko ◽  
M. Eby
Keyword(s):  
Carbon Sink ◽  
Surface Wind ◽  
Extended Period ◽  
Meridional Overturning Circulation ◽  
Biogeochemical Model ◽  
Model Driven ◽  
Ocean Biogeochemical Model ◽  
Meridional Overturning ◽  
Ocean Carbon ◽  
Induced Changes

Abstract. We estimate changes in the historical ocean carbon sink and their uncertainty using an ocean biogeochemical model driven with wind forcing from six different reanalyses and using two different eddy parameterization schemes. First, we quantify wind-induced changes over the extended period from 1871 to 2010 using the 20th Century Reanalysis winds. Consistent with previous shorter-term studies, we find that the wind changes act to reduce the ocean carbon sink, but the wind-induced trends are subject to large uncertainties. One major source of uncertainty is the parameterization of mesoscale eddies in our coarse resolution simulations. Trends in the Southern Ocean residual meridional overturning circulation and the globally integrated surface carbon flux over 1950 to 2010 are about 2.5 times smaller when using a variable eddy transfer coefficient than when using a constant coefficient in this parameterization. A second major source of uncertainty arises from disagreement on historical wind trends. By comparing six reanalyses over 1980 to 2010, we show that there are statistically significant differences in estimated historical wind trends, which vary in both sign and magnitude amongst the products. Through simulations forced with these reanalysis winds, we show that the influence of historical wind changes on ocean carbon uptake is highly uncertain, and the resulting trends depend on the choice of surface wind product.

scholarly journals Assessing the Role of High‐Frequency Winds and Sea Ice Loss on Arctic Phytoplankton Blooms in an Ice‐Ocean‐Biogeochemical Model

2019 ◽  
Vol 124 (9) ◽  
pp. 2728-2750 ◽  
Author(s):  
L. Castro de la Guardia ◽  
Y. Garcia‐Quintana ◽  
M. Claret ◽  
X. Hu ◽  
E. D. Galbraith ◽  
...  
Keyword(s):  
Sea Ice ◽  
High Frequency ◽  
Biogeochemical Model ◽  
Phytoplankton Blooms ◽  
Ocean Biogeochemical Model

scholarly journals PISCES-v2: an ocean biogeochemical model for carbon and ecosystem studies

2015 ◽  
Vol 8 (2) ◽  
pp. 1375-1509 ◽  
Author(s):  
O. Aumont ◽  
C. Ethé ◽  
A. Tagliabue ◽  
L. Bopp ◽  
M. Gehlen
Keyword(s):  
Growth Rate ◽  
Marine Ecosystem ◽  
Trophic Levels ◽  
Full Description ◽  
Biogeochemical Model ◽  
Ecosystem Studies ◽  
Ocean Biogeochemical Model ◽  
Iron Chemistry ◽  
Steady State Simulation

Abstract. PISCES-v2 is a biogeochemical model which simulates the lower trophic levels of marine ecosystem (phytoplankton, microzooplankton and mesozooplankton) and the biogeochemical cycles of carbon and of the main nutrients (P, N, Fe, and Si). The model is intended to be used for both regional and global configurations at high or low spatial resolutions as well as for short-term (seasonal, interannual) and long-term (climate change, paleoceanography) analyses. There are twenty-four prognostic variables (tracers) including two phytoplankton compartments (diatoms and nanophytoplankton), two zooplankton size-classes (microzooplankton and mesozooplankton) and a description of the carbonate chemistry. Formulations in PISCES-v2 are based on a mixed Monod–Quota formalism: on one hand, stoichiometry of C/N/P is fixed and growth rate of phytoplankton is limited by the external availability in N, P and Si. On the other hand, the iron and silicium quotas are variable and growth rate of phytoplankton is limited by the internal availability in Fe. Various parameterizations can be activated in PISCES-v2, setting for instance the complexity of iron chemistry or the description of particulate organic materials. So far, PISCES-v2 has been coupled to the NEMO and ROMS systems. A full description of PISCES-v2 and of its optional functionalities is provided here. The results of a quasi-steady state simulation are presented and evaluated against diverse observational and satellite-derived data. Finally, some of the new functionalities of PISCES-v2 are tested in a series of sensitivity experiments.

Phytoplankton and iron: validation of a global three-dimensional ocean biogeochemical model

2003 ◽  
Vol 50 (22-26) ◽  
pp. 3143-3169 ◽  
Author(s):  
Watson W. Gregg ◽  
Paul Ginoux ◽  
Paul S. Schopf ◽  
Nancy W. Casey
Keyword(s):  
Three Dimensional ◽  
Biogeochemical Model ◽  
Ocean Biogeochemical Model

scholarly journals The effect of marine aggregate parameterisations on nutrients and oxygen minimum zones in a global biogeochemical model

2019 ◽  
Vol 16 (15) ◽  
pp. 3095-3111 ◽  
Author(s):  
Daniela Niemeyer ◽  
Iris Kriest ◽  
Andreas Oschlies
Keyword(s):  
Model Calibration ◽  
Model Performance ◽  
Sensitivity Study ◽  
Global Model ◽  
Particle Aggregation ◽  
Biogeochemical Model ◽  
Regional Patterns ◽  
Oxygen Minimum Zones ◽  
The Impact ◽  
Oxygen Minimum

Abstract. Particle aggregation determines the particle flux length scale and affects the marine oxygen concentration and thus the volume of oxygen minimum zones (OMZs) that are of special relevance for ocean nutrient cycles and marine ecosystems and that have been found to expand faster than can be explained by current state-of-the-art models. To investigate the impact of particle aggregation on global model performance, we carried out a sensitivity study with different parameterisations of marine aggregates and two different model resolutions. Model performance was investigated with respect to global nutrient and oxygen concentrations, as well as extent and location of OMZs. Results show that including an aggregation model improves the representation of OMZs. Moreover, we found that besides a fine spatial resolution of the model grid, the consideration of porous particles, an intermediate-to-high particle sinking speed and a moderate-to-high stickiness improve the model fit to both global distributions of dissolved inorganic tracers and regional patterns of OMZs, compared to a model without aggregation. Our model results therefore suggest that improvements not only in the model physics but also in the description of particle aggregation processes can play a substantial role in improving the representation of dissolved inorganic tracers and OMZs on a global scale. However, dissolved inorganic tracers are apparently not sufficient for a global model calibration, which could necessitate global model calibration against a global observational dataset of marine organic particles.

scholarly journals A reactivity continuum of particulate organic matter in a global ocean biogeochemical model

2016 ◽  
Author(s):  
Olivier Aumont ◽  
Marco van Hulten ◽  
Matthieu Roy-Barman ◽  
Jean-Claude Dutay ◽  
Christian Ethé ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Critical Role ◽  
Oxygen Demand ◽  
Sediment Oxygen Demand ◽  
Global Ocean ◽  
Biogeochemical Model ◽  
Mesopelagic Zone ◽  
Ocean Biogeochemical Model ◽  
The Impact ◽  
Reactivity Continuum

Abstract. The marine biological carbon pump is dominated by the vertical transfer of Particulate Organic Carbon (POC) from the surface ocean to its interior. The efficiency of this transfer plays an important role in controlling the amount of atmospheric carbon that is sequestered in the ocean. Furthermore, the abundance and composition of POC is critical for the removal of numerous trace elements by scavenging, a number of which such as iron are essential for the growth of marine organisms, including phytoplankton. Observations and laboratory experiments have shown that POC is composed of numerous organic compounds that can have very different reactivities. Yet, this variable reactivity of POC has never been extensively considered, especially in modeling studies. Here, we introduced in the global ocean biogeochemical model NEMO-PISCES a description of the variable composition of POC based on the theoretical Reactivity Continuum Model proposed by (Boudreau and Ruddick, 1991). Our model experiments show that accounting for a variable lability of POC increases POC concentrations in the ocean’s interior by one to two orders of magnitude. This increase is mainly the consequence of a better preservation of small particles that sink slowly from the surface. Comparison with observations is significantly improved both in abundance and in size distribution. Furthermore, the amount of carbon that reaches the sediments is increased by more than a factor of two, which is in better agreement with global estimates of the sediment oxygen demand. The impact on the major macro-nutrients (nitrate and phosphate) remains modest. However, iron (Fe) distribution is strongly altered, especially in the upper mesopelagic zone as a result of more intense scavenging: Vertical gradients in Fe are milder in the upper ocean which appears to be closer to observations. Thus, our study shows that the variable lability of POC can play a critical role in the marine biogeochemical cycles which advocates for more dedicated in situ and laboratory experiments.

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