scholarly journals Corrigendum to "Relationships between the surface concentration of particulate organic carbon and optical properties in the eastern South Pacific and eastern Atlantic Oceans'' published in Biogeosciences, 5, 171–201, 2008

2008 ◽  
Vol 5 (2) ◽  
pp. 595-595 ◽  
Author(s):  
D. Stramski
Keyword(s):  
Optical Properties ◽  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
South Pacific ◽  
Surface Concentration

scholarly journals Relationships between the surface concentration of particulate organic carbon and optical properties in the eastern South Pacific and eastern Atlantic Oceans

2008 ◽  
Vol 5 (1) ◽  
pp. 171-201 ◽  
Author(s):  
D. Stramski ◽  
R. A. Reynolds ◽  
M. Babin ◽  
S. Kaczmarek ◽  
M. R. Lewis ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Coastal Upwelling ◽  
Empirical Relationship ◽  
South Pacific ◽  
Surface Concentration ◽  
Optical Measurements ◽  
Error Statistics ◽  
Empirical Relationships ◽  
Data Set

Abstract. We have examined several approaches for estimating the surface concentration of particulate organic carbon, POC, from optical measurements of spectral remote-sensing reflectance, Rrs(λ), using field data collected in tropical and subtropical waters of the eastern South Pacific and eastern Atlantic Oceans. These approaches include a direct empirical relationship between POC and the blue-to-green band ratio of reflectance, Rrs(λB)/Rrs(555), and two-step algorithms that consist of relationships linking reflectance to an inherent optical property IOP (beam attenuation or backscattering coefficient) and POC to the IOP. We considered two-step empirical algorithms that exclusively include pairs of empirical relationships and two-step hybrid algorithms that consist of semianalytical models and empirical relationships. The surface POC in our data set ranges from about 10 mg m−3 within the South Pacific Subtropical Gyre to 270 mg m−3 in the Chilean upwelling area, and ancillary data suggest a considerable variation in the characteristics of particulate assemblages in the investigated waters. The POC algorithm based on the direct relationship between POC and Rrs(λB)/Rrs(555) promises reasonably good performance in the vast areas of the open ocean covering different provinces from hyperoligotrophic and oligotrophic waters within subtropical gyres to eutrophic coastal upwelling regimes characteristic of eastern ocean boundaries. The best error statistics were found for power function fits to the data of POC vs. Rrs(443)/Rrs(555) and POC vs. Rrs(490)/Rrs(555). For our data set that includes over 50 data pairs, these relationships are characterized by the mean normalized bias of about 2% and the normalized root mean square error of about 20%. We recommend that these algorithms be implemented for routine processing of ocean color satellite data to produce maps of surface POC with the status of an evaluation data product for continued work on algorithm development and refinements. The two-step algorithms also deserve further attention because they can utilize various models for estimating IOPs from reflectance, offer advantages for developing an understanding of bio-optical variability underlying the algorithms, and provide flexibility for regional or seasonal parameterizations of the algorithms.

scholarly journals Relationships between the surface concentration of particulate organic carbon and optical properties in the eastern South Pacific and eastern Atlantic Oceans

2007 ◽  
Vol 4 (5) ◽  
pp. 3453-3530 ◽  
Author(s):  
D. Stramski ◽  
R. A. Reynolds ◽  
M. Babin ◽  
S. Kaczmarek ◽  
M. R. Lewis ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Coastal Upwelling ◽  
Empirical Relationship ◽  
South Pacific ◽  
Surface Concentration ◽  
Optical Measurements ◽  
Error Statistics ◽  
Empirical Relationships ◽  
Data Set

Abstract. We have examined several approaches for estimating the surface concentration of particulate organic carbon, POC, from optical measurements of remote-sensing reflectance, Rrs(λ), using field data collected in tropical and subtropical waters of the eastern South Pacific and eastern Atlantic Oceans. These approaches include a direct empirical relationship between POC and the blue-to-green band ratio of reflectance, Rrs(λB)/Rrs(555), and two-step algorithms that consist of relationships linking reflectance to an inherent optical property IOP (beam attenuation or backscattering coefficient) and POC to the IOP. We considered two-step empirical algorithms that exclusively include pairs of empirical relationships and two-step hybrid algorithms that consist of semianalytical models and empirical relationships. The surface POC in our data set ranges from about 10 mg m-3 within the South Pacific Subtropical Gyre to 270 mg m-3 in the Chilean upwelling area, and data on phytoplankton pigments, suspended particulate matter, and the backscattering ratio suggest a considerable variation in the composition of particulate assemblages in the investigated waters. The POC algorithm based on the direct relationship between POC and Rrs(λB)/Rrs(555) promises reasonably good performance in the vast areas of the open ocean covering different provinces from hyperoligotrophic and oligotrophic waters within subtropical gyres to eutrophic coastal upwelling regimes characteristic of eastern ocean boundaries. The best error statistics were found for power function fits to the data of POC vs. Rrs(443)/Rrs(555) and POC vs. Rrs(490)/Rrs(555). For our data set that includes over 50 data pairs, these relationships are characterized by the mean normalized bias of about 2% and the normalized root mean square error of about 20%. We recommend that these algorithms be implemented for routine processing of ocean color satellite data to produce maps of surface POC with the status of an evaluation data product for continued work on algorithm development and refinements. The two-step algorithms also deserve further attention because they can utilize various models for estimating IOPs from reflectance, offer advantages for developing an understanding of bio-optical variability underlying the algorithms, and provide flexibility for regional or seasonal parameterizations of the algorithms.

scholarly journals ESTIMATION OF OCEANIC PARTICULATE ORGANIC CARBON WITH MACHINE LEARNING

2020 ◽  
Vol V-2-2020 ◽  
pp. 949-956
Author(s):  
R. Sauzède ◽  
J. E. Johnson ◽  
H. Claustre ◽  
G. Camps-Valls ◽  
A. B. Ruescas
Keyword(s):  
Machine Learning ◽  
Optical Properties ◽  
Organic Carbon ◽  
Vertical Distribution ◽  
Particulate Organic Carbon ◽  
Ocean Color ◽  
Global Scale ◽  
Vertical Profiles ◽  
The Vertical Distribution ◽  
Satellite Ocean Color

Abstract. Understanding and quantifying ocean carbon sinks of the planet is of paramount relevance in the current scenario of global change. Particulate organic carbon (POC) is a key biogeochemical parameter that helps us characterize export processes of the ocean. Ocean color observations enable the estimation of bio-optical proxies of POC (i.e. particulate backscattering coefficient, bbp) in the surface layer of the ocean quasi-synoptically. In parallel, the Argo program distributes vertical profiles of the physical properties with a global coverage and a high spatio-temporal resolution. Merging satellite ocean color and Argo data using a neural networkbased method has already shown strong potential to infer the vertical distribution of bio-optical properties at global scale with high space-time resolution. This method is trained and validated using a database of concurrent vertical profiles of temperature, salinity, and bio-optical properties, i.e. bbp, collected by Biogeochemical-Argo (BGC-Argo) floats, matched up with satellite ocean color products. The present study aims at improving this method by 1) using a larger dataset from BGC-Argo network since 2016 for training, 2) using additional inputs such as altimetry data, which provide significant information on mesoscale processes impacting the vertical distribution of bbp, 3) improving the vertical resolution of estimation, and 4) examining the potential of alternative machine learning-based techniques. As a first attempt with the new data, we used some feature-specific preprocessing routines followed by a Multi-Output Random Forest algorithm on two regions with different ocean dynamics: North Atlantic and Subtropical Gyres. The statistics and the bbp profiles obtained from the validation floats show promising results and suggest this direction is worth investigating even further at global scale.

scholarly journals Optical Properties and Biochemical Indices of Marine Particles in the Open Mediterranean Sea: The R/V Maria S. Merian Cruise, March 2018

2021 ◽  
Vol 9 ◽  
Author(s):  
Spyros Chaikalis ◽  
Constantine Parinos ◽  
Jürgen Möbius ◽  
Alexandra Gogou ◽  
Dimitris Velaoras ◽  
...  
Keyword(s):  
Optical Properties ◽  
Particulate Matter ◽  
Organic Carbon ◽  
Mediterranean Sea ◽  
Particulate Organic Carbon ◽  
Beam Attenuation ◽  
Median Diameter ◽  
The Mediterranean ◽  
Biochemical Indices ◽  
Beam Attenuation Coefficient

A rich data set on particulate matter optical properties and parameters (beam attenuation coefficient, volume concentration, particle size and PSD slope), accompanied by measurements of biochemical indices (particulate organic carbon, particulate nitrogen and their stable isotopic composition) was obtained from the surface to deep waters across the Mediterranean Sea, in March-April 2018. A decrease of beam attenuation coefficients, total particle volume concentrations, particulate organic carbon and nitrogen concentrations was noted towards the eastern Mediterranean Sea (EMed) in comparison to the western Mediterranean Sea (WMed). LISST-derived optical properties were significantly correlated with water mass characteristics. Overall, the most turbid water mass identified in the Mediterranean Sea was the Surface Atlantic water (AW), and the most transparent was the Transitional Mediterranean Water (TMW) in the Cretan Sea, whereas a general decrease in particulate matter concentration is observed from the WMed towards the EMed. Relatively depleted δ13C-POC values in the particle pool of the open Mediterranean Sea can be attributed to contribution from terrestrial inputs, mainly via atmospheric deposition. Throughout the entire water column, a significant positive correlation between particle beam attenuation coefficient and particulate organic carbon concentration is observed in the open Mediterranean Sea. Such relationship suggests the predominance of organic particles with biogenic origin. POC concentration and particle median diameter D50 are significantly and negatively correlated both in the WMed and the EMed Sea, confirming that small particles are POC-rich. At depth, a prominent decrease of most measured parameters was observed, with the exception of particle median diameter that increased substantially in the EMed towards the deep sea, suggesting potentially enhanced aggregation processes. The low particle size distribution slope ξ observed in the EMed, corresponding to larger particle populations, supports the above notion. Basin-wide Rayleigh-type isotopic fractionation in vertical profiles of δ15N-PN across the Mediterranean Sea, underlines the differences in the trophic characters of the two sub-basins and highlights the role of circulation changes on biogeochemical parameters and the redistribution of particulate matter as a source of nutrients in the water column.

scholarly journals Particulate organic carbon and inherent optical properties during 2008 North Atlantic Bloom Experiment

2012 ◽  
Vol 117 (C6) ◽  
pp. n/a-n/a ◽  
Author(s):  
Ivona Cetinić ◽  
Mary Jane Perry ◽  
Nathan T. Briggs ◽  
Emily Kallin ◽  
Eric A. D'Asaro ◽  
...  
Keyword(s):  
Optical Properties ◽  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
North Atlantic ◽  
Inherent Optical Properties

scholarly journals Dissolved and particulate organic carbon in Icelandic proglacial streams

2018 ◽  
Author(s):  
Peter Chifflard ◽  
Christina Fasching ◽  
Martin Reiss ◽  
Lukas Ditzel
Keyword(s):  
Organic Matter ◽  
Optical Properties ◽  
Organic Carbon ◽  
Microbial Communities ◽  
Particulate Organic Carbon ◽  
Ice Cap ◽  
Glacier Terminus ◽  
Aromatic Content ◽  
Doc Concentration ◽  
First Time

Abstract. Here for the first time, we analyze the concentration of dissolved (DOC) and particulate organic carbon (POC), as well as its optical properties (absorbance and fluorescence) in proglacial streams of Iceland, location of Europe's largest nonpolar ice cap. DOC and POC concentrations range from 0.11 mg L−1 to 0.94 mg L−1 and from 0.67 mg L−1 to 173.33 mg L−1, respectively. We estimate an annual release of 0.008 Tg C yr−1 (DOC) and 1.72 Tg C yr−1 (POC) from Icelandic glaciers. Compared to the global release of 1.97 Tg C yr−1 POC, these first calculations underline the necessity to include the Icelandic glaciers in global organic carbon budgets. Based on optical properties, we found that although glacial derived organic matter (OM) was dominated by proteinaceous florescence, organic matter composition was variable among glaciers, often exhibiting relatively higher aromatic content and increased humification closer to the glacier terminus, modulated by the presence of glacial lakes. While POC concentration decreased downstream, DOC concentration as well as the autochthonous fraction of OM increased suggesting the reworking of the OC by microbial communities, which has implications for downstream ecosystems as glaciers continue to melt.

scholarly journals Shallow particulate organic carbon regeneration in the South Pacific Ocean

2019 ◽  
Vol 116 (20) ◽  
pp. 9753-9758 ◽  
Author(s):  
Frank J. Pavia ◽  
Robert F. Anderson ◽  
Phoebe J. Lam ◽  
B. B. Cael ◽  
Sebastian M. Vivancos ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Carbon Storage ◽  
South Pacific ◽  
Spatiotemporal Variability ◽  
Length Scales ◽  
Poc Flux ◽  
Carbon Transfer ◽  
Ocean Carbon ◽  
Carbon Regeneration

Particulate organic carbon (POC) produced in the surface ocean sinks through the water column and is respired at depth, acting as a primary vector sequestering carbon in the abyssal ocean. Atmospheric carbon dioxide levels are sensitive to the length (depth) scale over which respiration converts POC back to inorganic carbon, because shallower waters exchange with the atmosphere more rapidly than deeper ones. However, estimates of this carbon regeneration length scale and its spatiotemporal variability are limited, hindering the ability to characterize its sensitivity to environmental conditions. Here, we present a zonal section of POC fluxes at high vertical and spatial resolution from the GEOTRACES GP16 transect in the eastern tropical South Pacific, based on normalization to the radiogenic thorium isotope 230Th. We find shallower carbon regeneration length scales than previous estimates for the oligotrophic South Pacific gyre, indicating less efficient carbon transfer to the deep ocean. Carbon regeneration is strongly inhibited within suboxic waters near the Peru coast. Canonical Martin curve power laws inadequately capture POC flux profiles at suboxic stations. We instead fit these profiles using an exponential function with flux preserved at depth, finding shallow regeneration but high POC sequestration below 1,000 m. Both regeneration length scales and POC flux at depth closely track the depths at which oxygen concentrations approach zero. Our findings imply that climate warming will result in reduced ocean carbon storage due to expanding oligotrophic gyres, but opposing effects on ocean carbon storage from expanding suboxic waters will require modeling and future work to disentangle.

scholarly journals Contribution of picoplankton to the total particulate organic carbon (POC) concentration in the eastern South Pacific

2007 ◽  
Vol 4 (3) ◽  
pp. 1461-1497 ◽  
Author(s):  
C. Grob ◽  
O. Ulloa ◽  
H. Claustre ◽  
Y. Huot ◽  
G. Alarcón ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Spatial Variability ◽  
Particulate Organic Carbon ◽  
Attenuation Coefficient ◽  
South Pacific ◽  
Particle Beam ◽  
Trophic Conditions ◽  
Carbon Biomass ◽  
Organic Carbon Concentration ◽  
Total Particle

Abstract. Prochlorococcus, Synechococcus, picophytoeukaryotes and bacterioplankton abundances and contributions to the total particulate organic carbon concentration (POC), derived from the total particle beam attenuation coefficient (cp), were determined across the eastern South Pacific between the Marquesas Islands and the coast of Chile. All flow cytometrically derived abundances decreased towards the hyper-oligotrophic centre of the gyre and were highest at the coast, except for Prochlorococcus, which is not detected under eutrophic conditions. Temperature and nutrient availability appeared important in modulating picophytoplankton abundance, according to the prevailing trophic conditions. Although the non-vegetal particles tended to dominate the cp signal everywhere along the transect (50 to 83%), this dominance seemed to weaken from oligo- to eutrophic conditions, the contributions by vegetal and non-vegetal particles being about equal under mature upwelling conditions. Spatial variability in the vegetal compartment was more important than the non-vegetal one in shaping the water column particulate attenuation coefficient. Spatial variability in picophytoplankton biomass could be traced by changes in both Tchla and cp. Finally, picophytoeukaryotes contributed with ~38% on average to the total integrated phytoplankton carbon biomass or vegetal attenuation signal along the transect, as determined by direct size measurements on cells sorted by flow cytometry and optical theory. The role of picophytoeukaryotes in carbon and energy flow would therefore be very important, even under hyper-oligotrophic conditions.

scholarly journals Water column distribution and carbon isotopic signal of cholesterol, brassicasterol and particulate organic carbon in the Atlantic sector of the Southern Ocean

2013 ◽  
Vol 10 (4) ◽  
pp. 2787-2801 ◽  
Author(s):  
A.-J. Cavagna ◽  
F. Dehairs ◽  
S. Bouillon ◽  
V. Woule-Ebongué ◽  
F. Planchon ◽  
...  
Keyword(s):  
Surface Water ◽  
Organic Carbon ◽  
Southern Ocean ◽  
Water Column ◽  
Particulate Organic Carbon ◽  
Environmental Changes ◽  
Surface Concentration ◽  
Polar Front ◽  
Atlantic Sector ◽  
Organic C

Abstract. The combination of concentrations and δ13C signatures of Particulate Organic Carbon (POC) and sterols provides a powerful approach to study ecological and environmental changes in both the modern and ancient ocean. We applied this tool to study the biogeochemical changes in the modern ocean water column during the BONUS-GoodHope survey (February–March 2008) from Cape Basin to the northern part of the Weddell Gyre. Cholesterol and brassicasterol were chosen as ideal biomarkers of the heterotrophic and autotrophic carbon pools, respectively, because of their ubiquitous and relatively refractory nature. We document depth distributions of concentrations (relative to bulk POC) and δ13C signatures of cholesterol and brassicasterol combined with CO2 aq. surface concentration variation. While the relationship between CO2 aq. and δ13C of bulk POC and biomarkers have been reported by others for the surface water, our data show that this persists in mesopelagic and deep waters, suggesting that δ13C signatures of certain biomarkers in the water column could be applied as proxies for surface water CO2 aq. We observed a general increase in sterol δ13C signatures with depth, which is likely related to a combination of particle size effects, selective feeding on larger cells by zooplankton, and growth rate related effects. Our data suggest a key role of zooplankton fecal aggregates in carbon export for this part of the Southern Ocean (SO). Additionally, in the southern part of the transect south of the Polar Front (PF), the release of sea-ice algae during the ice demise in the Seasonal Ice Zone (SIZ) is hypothesized to influence the isotopic signature of sterols in the open ocean. Overall, the combined use of δ13C values and concentrations measurements of both bulk organic C and specific sterols throughout the water column offers the promising potential to explore the recent history of plankton and the fate of organic matter in the SO.

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