scholarly journals A multi-variable box model approach to the soft tissue carbon pump

2010 ◽  
Vol 6 (6) ◽  
pp. 827-841 ◽  
Author(s):  
A. M. de Boer ◽  
A. J. Watson ◽  
N. R. Edwards ◽  
K. I. C. Oliver
Keyword(s):  
Soft Tissue ◽  
Numerical Models ◽  
Nutrient Utilization ◽  
Atmospheric Co2 ◽  
Box Model ◽  
Co2 Uptake ◽  
Residual Circulation ◽  
Biological Mechanisms ◽  
Export Production ◽  
Model Approach

Abstract. The canonical question of which physical, chemical or biological mechanisms were responsible for oceanic uptake of atmospheric CO2 during the last glacial is yet unanswered. Insight from paleo-proxies has led to a multitude of hypotheses but none so far have been convincingly supported in three dimensional numerical modelling experiments. The processes that influence the CO2 uptake and export production are inter-related and too complex to solve conceptually while complex numerical models are time consuming and expensive to run which severely limits the combinations of mechanisms that can be explored. Instead, an intermediate inverse box model approach of the soft tissue pump is used here in which the whole parameter space is explored. The glacial circulation and biological production states are derived from these using proxies of glacial export production and the need to draw down CO2 into the ocean. We find that circulation patterns which explain glacial observations include reduced Antarctic Bottom Water formation and high latitude upwelling and mixing of deep water and to a lesser extent reduced equatorial upwelling. The proposed mechanism of CO2 uptake by an increase of eddies in the Southern Ocean, leading to a reduced residual circulation, is not supported. Regarding biological mechanisms, an increase in the nutrient utilization in either the equatorial regions or the northern polar latitudes can reduce atmospheric CO2 and satisfy proxies of glacial export production. Consistent with previous studies, CO2 is drawn down more easily through increased productivity in the Antarctic region than the sub-Antarctic, but that violates observations of lower export production there. The glacial states are more sensitive to changes in the circulation and less sensitive to changes in nutrient utilization rates than the interglacial states.

scholarly journals A comprehensive, multi-process box-model approach to glacial-interglacial carbon cycling

2010 ◽  
Vol 6 (3) ◽  
pp. 867-903 ◽  
Author(s):  
A. M. de Boer ◽  
A. J. Watson ◽  
N. R. Edwards ◽  
K. I. C. Oliver
Keyword(s):  
Numerical Models ◽  
Three Dimensional ◽  
Nutrient Utilization ◽  
Atmospheric Co2 ◽  
Box Model ◽  
Co2 Uptake ◽  
Residual Circulation ◽  
Biological Mechanisms ◽  
Export Production ◽  
Model Approach

Abstract. The canonical question of which physical, chemical or biological mechanisms were responsible for oceanic uptake of atmospheric CO2 during the last glacial is yet unanswered. Insight from paleo proxies has led to a multitude of hypotheses but none so far have been convincingly supported in three dimensional numerical modelling experiments. The processes that influence the CO2 uptake and export production are inter-related and too complex to solve conceptually while complex numerical models are time consuming and expensive to run which severely limits the combinations of mechanisms that can be explored. Instead, an intermediate inverse box model approach is used here in which the whole parameter space is explored. The glacial circulation and biological production states are derived from these using proxies of glacial export production and the need to draw down CO2 into the ocean. We find that circulation patterns which explain glacial observations include reduced Antarctic Bottom Water formation and high latitude mixing and to a lesser extent reduced equatorial upwelling. The proposed mechanism of CO2 uptake by an increase of eddies in the Southern Ocean, leading to a reduced residual circulation, is not supported. Regarding biological mechanisms, an increase in the nutrient utilization in either the equatorial regions or the northern polar latitudes can reduce atmospheric CO2 and satisfy proxies of glacial export production. Consistent with previous studies, CO2 is drawn down more easily through increased productivity in the Antarctic region than the sub-Antarctic, but that violates observations of lower export production there.

scholarly journals Rates of consumption of atmospheric CO<sub>2</sub> through the weathering of loess during the next 100 yr of climate change

2013 ◽  
Vol 10 (1) ◽  
pp. 135-148 ◽  
Author(s):  
Y. Goddéris ◽  
S. L. Brantley ◽  
L. M. François ◽  
J. Schott ◽  
D. Pollard ◽  
...  
Keyword(s):  
Climate Change ◽  
Reaction Front ◽  
Numerical Models ◽  
Atmospheric Co2 ◽  
Co2 Production ◽  
Depth Interval ◽  
Mississippi Valley ◽  
The South ◽  
The North ◽  
The Future

Abstract. Quantifying how C fluxes will change in the future is a complex task for models because of the coupling between climate, hydrology, and biogeochemical reactions. Here we investigate how pedogenesis of the Peoria loess, which has been weathering for the last 13 kyr, will respond over the next 100 yr of climate change. Using a cascade of numerical models for climate (ARPEGE), vegetation (CARAIB) and weathering (WITCH), we explore the effect of an increase in CO2 of 315 ppmv (1950) to 700 ppmv (2100 projection). The increasing CO2 results in an increase in temperature along the entire transect. In contrast, drainage increases slightly for a focus pedon in the south but decreases strongly in the north. These two variables largely determine the behavior of weathering. In addition, although CO2 production rate increases in the soils in response to global warming, the rate of diffusion back to the atmosphere also increases, maintaining a roughly constant or even decreasing CO2 concentration in the soil gas phase. Our simulations predict that temperature increasing in the next 100 yr causes the weathering rates of the silicates to increase into the future. In contrast, the weathering rate of dolomite – which consumes most of the CO2 – decreases in both end members (south and north) of the transect due to its retrograde solubility. We thus infer slower rates of advance of the dolomite reaction front into the subsurface, and faster rates of advance of the silicate reaction front. However, additional simulations for 9 pedons located along the north–south transect show that the dolomite weathering advance rate will increase in the central part of the Mississippi Valley, owing to a maximum in the response of vertical drainage to the ongoing climate change. The carbonate reaction front can be likened to a terrestrial lysocline because it represents a depth interval over which carbonate dissolution rates increase drastically. However, in contrast to the lower pH and shallower lysocline expected in the oceans with increasing atmospheric CO2, we predict a deeper lysocline in future soils. Furthermore, in the central Mississippi Valley, soil lysocline deepening accelerates but in the south and north the deepening rate slows. This result illustrates the complex behavior of carbonate weathering facing short term global climate change. Predicting the global response of terrestrial weathering to increased atmospheric CO2 and temperature in the future will mostly depend upon our ability to make precise assessments of which areas of the globe increase or decrease in precipitation and soil drainage.

scholarly journals A multi-box model study of the role of the biospheric metabolism in the recent decline of δ18O in atmospheric CO2

Tellus B ◽  
2002 ◽  
Vol 54 (4) ◽  
pp. 307-324
Author(s):  
Misa Ishizawa ◽  
Takakiyo Nakazawa ◽  
Kaz Higuchi
Keyword(s):  
Atmospheric Co2 ◽  
Box Model ◽  
Model Study

scholarly journals Linking the lithogenic, atmospheric, and biogenic cycles of silicate, carbonate, and organic carbon in the ocean

2009 ◽  
Vol 6 (4) ◽  
pp. 6579-6599
Author(s):  
S. V. Smith ◽  
J.-P. Gattuso
Keyword(s):  
Carbon Storage ◽  
Chemical Weathering ◽  
Dissolved Inorganic Carbon ◽  
North Pacific Ocean ◽  
Atmospheric Co2 ◽  
Molar Ratio ◽  
Co2 Uptake ◽  
Organic C ◽  
Co2 Gas ◽  
The Relationship

Abstract. Geochemical theory describes long term cycling of atmospheric CO2 between the atmosphere and rocks at the Earth surface in terms of rock weathering and precipitation of sedimentary minerals. Chemical weathering of silicate rocks takes up atmospheric CO2, releases cations and HCO3− to water, and precipitates SiO2, while CaCO3 precipitation consumes Ca2+ and HCO3− and releases one mole of CO2 to the atmosphere for each mole of CaCO3 precipitated. At steady state, according to this theory, the CO2 uptake and release should equal one another. In contradiction to this theory, carbonate precipitation in the present surface ocean releases only about 0.6 mol of CO2 per mole of carbonate precipitated. This is a result of the buffer effect described by Ψ, the molar ratio of net CO2 gas evasion to net CaCO3 precipitation from seawater in pCO2 equilibrium with the atmosphere. This asymmetry in CO2 flux between weathering and precipitation would quickly exhaust atmospheric CO2, posing a conundrum in the classical weathering and precipitation cycle. While often treated as a constant, Ψ actually varies as a function of salinity, pCO2, and temperature. Introduction of organic C reactions into the weathering-precipitation couplet largely reconciles the relationship. ψ in the North Pacific Ocean central gyre rises from 0.6 to 0.9, as a consequence of organic matter oxidation in the water column. ψ records the combined effect of CaCO3 and organic reactions and storage of dissolved inorganic carbon in the ocean, as well as CO2 gas exchange between the ocean and atmosphere. Further, in the absence of CaCO3 reactions, Ψ would rise to 1.0. Similarly, increasing atmospheric pCO2 over time, which leads to ocean acidification, alters the relationship between organic and inorganic C reactions and carbon storage in the ocean. Thus, the carbon reactions and ψ can cause large variations in oceanic carbon storage with little exchange with the atmosphere.

Testing regression and mean model approaches to facial soft-tissue thickness estimation

2020 ◽  
pp. 002580242097701
Author(s):  
Tobias MR Houlton ◽  
Nicolene Jooste ◽  
Maryna Steyn
Keyword(s):  
Soft Tissue ◽  
Regression Model ◽  
South African ◽  
Goodness Of Fit ◽  
Regression Equations ◽  
Tissue Thickness ◽  
Facial Soft Tissue ◽  
Soft Tissue Thickness ◽  
Subject Specific ◽  
Model Approach

Average facial soft-tissue thickness (FSTT) databanks are continuously developed and applied within craniofacial identification. This study considered and tested a subject-specific regression model alternative for estimating the FSTT values for oral midline landmarks using skeletal projection measurements. Measurements were taken from cone-beam computed tomography scans of 100 South African individuals (60 male, 40 female; Mage = 35 years). Regression equations incorporating sex categories were generated. This significantly improved the goodness-of-fit ( r2-value). Validation tests compared the constructed regression models with mean FSTT data collected from this study, existing South African FSTT data, a universal total weighted mean approach with pooled demographic data and collection techniques and a regression model approach that uses bizygomatic width and maximum cranial breadth dimensions. The generated regression equations demonstrated individualised results, presenting a total mean inaccuracy (TMI) of 1.53 mm using dental projection measurements and 1.55 mm using cemento-enamel junction projection measurements. These slightly outperformed most tested mean models (TMI ranged from 1.42 to 4.43 mm), and substantially outperformed the pre-existing regression model approach (TMI = 5.12 mm). The newly devised regressions offer a subject-specific solution to FSTT estimation within a South African population. A continued development in sample size and validation testing may help substantiate its application within craniofacial identification.

scholarly journals Can seasonal and interannual variation in landscape CO<sub>2</sub> fluxes be detected by atmospheric observations of CO<sub>2</sub> concentrations made at a tall tower?

2014 ◽  
Vol 11 (3) ◽  
pp. 735-747 ◽  
Author(s):  
T. L. Smallman ◽  
M. Williams ◽  
J. B. Moncrieff
Keyword(s):  
Interannual Variation ◽  
Atmospheric Transport ◽  
Co2 Exchange ◽  
Atmospheric Co2 ◽  
Co2 Uptake ◽  
Post Harvest ◽  
Co2 Concentrations ◽  
Prevailing Wind Direction ◽  
Atmospheric Co2 Concentrations ◽  
Tall Tower

Abstract. The coupled numerical weather model WRF-SPA (Weather Research and Forecasting model and Soil-Plant-Atmosphere model) has been used to investigate a 3 yr time series of observed atmospheric CO2 concentrations from a tall tower in Scotland, UK. Ecosystem-specific tracers of net CO2 uptake and net CO2 release were used to investigate the contributions to the tower signal of key land covers within its footprint, and how contributions varied at seasonal and interannual timescales. In addition, WRF-SPA simulated atmospheric CO2 concentrations were compared with two coarse global inversion models, CarbonTrackerEurope and the National Oceanic and Atmospheric Administration's CarbonTracker (CTE-CT). WRF-SPA realistically modelled both seasonal (except post harvest) and daily cycles seen in observed atmospheric CO2 at the tall tower (R2 = 0.67, rmse = 3.5 ppm, bias = 0.58 ppm). Atmospheric CO2 concentrations from the tall tower were well simulated by CTE-CT, but the inverse model showed a poorer representation of diurnal variation and simulated a larger bias from observations (up to 1.9 ppm) at seasonal timescales, compared to the forward modelling of WRF-SPA. However, we have highlighted a consistent post-harvest increase in the seasonal bias between WRF-SPA and observations. Ecosystem-specific tracers of CO2 exchange indicate that the increased bias is potentially due to the representation of agricultural processes within SPA and/or biases in land cover maps. The ecosystem-specific tracers also indicate that the majority of seasonal variation in CO2 uptake for Scotland's dominant ecosystems (forests, cropland and managed grassland) is detectable in observations within the footprint of the tall tower; however, the amount of variation explained varies between years. The between years variation in detectability of Scotland's ecosystems is potentially due to seasonal and interannual variation in the simulated prevailing wind direction. This result highlights the importance of accurately representing atmospheric transport used within atmospheric inversion models used to estimate terrestrial source/sink distribution and magnitude.

Sources and Sinks of Atmospheric CO2

1992 ◽  
Vol 40 (5) ◽  
pp. 407 ◽  
Author(s):  
JA Taylor ◽  
J Lloyd
Keyword(s):  
Climate Change ◽  
Biomass Burning ◽  
Transport Model ◽  
Atmospheric Co2 ◽  
Tropical Rainforests ◽  
Co2 Uptake ◽  
Tracer Transport ◽  
Intergovernmental Panel ◽  
Co2 Concentrations ◽  
Atmospheric Co2 Concentrations

The biosphere plays an important role in determining the sources, sinks, levels and rates of change of atmospheric CO2 concentrations. Significant uncertainties remain in estimates of the fluxes of CO2 from biomass burning and deforestation, and uptake and storage of CO2 by the biosphere arising from increased atmospheric CO2 concentrations. Calculation of probable rates of carbon sequestration for the major ecosystem complexes and global 3-D tracer transport model runs indicate the possibility that a significant net CO2 uptake (> 1 Pg C yr-1), a CO2 'fertilisation effect', may be occurring in tropical rainforests, effectively accounting for much of the 'missing sink'. This sink may currently balance much of the CO2 added to the atmosphere from deforestation and biomass burning. Interestingly, CO2 released from biomass burning may itself be playing an important role in enhanced carbon storage by tropical rainforests. This has important implications for predicting future CO2 concentrations. If tropical rainforest destruction continues then much of the CO2 stored as a result of the CO2 'fertilisation effect' will be rereleased to the atmosphere and much of the 'missing sink' will disappear. These effects have not been considered in the IPCC (Intergovernmental Panel on Climate Change) projections of future atmospheric CO2 concentrations. Predictions which take account of the combined effects of deforestation, the return of carbon previously stored through the CO2 'fertilisation effect' and the loss of a large proportion of the 'missing sink' as a result of deforestation, would result in much higher predicted concentrations and rates of increase of atmospheric CO2 and, as a consequence, accelerated rates of climate change.

The Role of Photosynthesis in Flowering of the Long-Day Plant Sinapis alba

1977 ◽  
Vol 4 (4) ◽  
pp. 467 ◽  
Author(s):  
M Bodson ◽  
RW King ◽  
LT Evans ◽  
G Bernier
Keyword(s):  
Sinapis Alba ◽  
High Irradiance ◽  
Atmospheric Co2 ◽  
Co2 Uptake ◽  
Long Day ◽  
Absolute Requirement ◽  
Full Flowering ◽  
Lower Irradiance ◽  
Short Days

Flowering can be induced in the long-day plant Sinapis alba in 8-h photoperiods provided that the irradiance is close to that at which leaf photosynthesis is light-saturated (e.g. 96 J m-2 s-1). Three such 8-h cycles result in 10% flowering and six are required for full flowering, whereas only one long-day cycle of 16-20 h duration at a much lower irradiance (25 J m-2 s-1) is required for full flowering. High irradiance during the single long day promotes flowering when given for the first 8 h of a 16-h photoperiod, but is inhibitory over the last 8 h. Photosynthetic CO2 uptake is crucial for this response to high irradiance, as both its inhibitory and promotive effects on flowering are reversed by the removal of atmospheric CO2 during the period of high irradiance. Compared with plants kept in short days (8-h photoperiod), export of 14C-labelled assimilates from the leaf during a 24-h period was only 50-60% greater in plants exposed to a long day (20-h photoperiod), because plants in short days compensated to a degree for their shorter photosynthetic period by mobilizing leaf reserves during darkness. However, flowering can occur with no evident enhancement of supply of assimilate to the shoot apex, for example following dis- placement of the short day or on removal of atmospheric CO2 during the last 12 h of exposure to a 20-h long day. Also, the flowering response to radiant flux density during the second half of a long day shows an optimum between 15 and 70 J m-2 s-1, with reduced flowering both above and below this irradiance. Thus, although there is no absolute requirement for long days to induce flowering in S. alba, light reactions cther than photosynthesis probably contribute to photoperiodic induction in this species.

Real-time monitoring of South American smoke particle emissions and transport using a coupled remote sensing/box-model approach

2004 ◽  
Vol 31 (6) ◽  
pp. n/a-n/a ◽  
Author(s):  
Jeffrey S. Reid ◽  
Elaine M. Prins ◽  
Douglas L. Westphal ◽  
Christopher C. Schmidt ◽  
Kim A. Richardson ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Real Time ◽  
Box Model ◽  
South American ◽  
Real Time Monitoring ◽  
Particle Emissions ◽  
Smoke Particle ◽  
Model Approach

scholarly journals Regional Impacts of Climate Change and Atmospheric CO2 on Future Ocean Carbon Uptake: A Multimodel Linear Feedback Analysis

2011 ◽  
Vol 24 (9) ◽  
pp. 2300-2318 ◽  
Author(s):  
Tilla Roy ◽  
Laurent Bopp ◽  
Marion Gehlen ◽  
Birgit Schneider ◽  
Patricia Cadule ◽  
...  
Keyword(s):  
Climate Change ◽  
North Atlantic Ocean ◽  
Climate Change Impacts ◽  
Atmospheric Co2 ◽  
Linear Feedback ◽  
Co2 Uptake ◽  
Co2 Solubility ◽  
Feedback Analysis ◽  
Anthropogenic Co2 ◽  
Atmospheric Co2 Concentrations

Abstract The increase in atmospheric CO2 over this century depends on the evolution of the oceanic air–sea CO2 uptake, which will be driven by the combined response to rising atmospheric CO2 itself and climate change. Here, the future oceanic CO2 uptake is simulated using an ensemble of coupled climate–carbon cycle models. The models are driven by CO2 emissions from historical data and the Special Report on Emissions Scenarios (SRES) A2 high-emission scenario. A linear feedback analysis successfully separates the regional future (2010–2100) oceanic CO2 uptake into a CO2-induced component, due to rising atmospheric CO2 concentrations, and a climate-induced component, due to global warming. The models capture the observation-based magnitude and distribution of anthropogenic CO2 uptake. The distributions of the climate-induced component are broadly consistent between the models, with reduced CO2 uptake in the subpolar Southern Ocean and the equatorial regions, owing to decreased CO2 solubility; and reduced CO2 uptake in the midlatitudes, owing to decreased CO2 solubility and increased vertical stratification. The magnitude of the climate-induced component is sensitive to local warming in the southern extratropics, to large freshwater fluxes in the extratropical North Atlantic Ocean, and to small changes in the CO2 solubility in the equatorial regions. In key anthropogenic CO2 uptake regions, the climate-induced component offsets the CO2-induced component at a constant proportion up until the end of this century. This amounts to approximately 50% in the northern extratropics and 25% in the southern extratropics and equatorial regions. Consequently, the detection of climate change impacts on anthropogenic CO2 uptake may be difficult without monitoring additional tracers, such as oxygen.

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