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  • Open Access English
    Authors: 
    Lauvset, Siv Kari; Key, Robert M.; Olsen, Are; van Heuven, Steven; Velo, Antón; Lin, Xiaohua; Schirnick, Carsten; Kozyr, Alex; Tanhua, Toste; Hoppema, Mario; +7 more
    Project: EC | SEADATANET II (283607), NSF | Support for International... (1243377), EC | CARBOCHANGE (264879), NSF | Southern Ocean Carbon and... (1425989), EC | AtlantOS (633211), NSF | Collaborative Research: C... (0825163)

    We present a mapped climatology (GLODAPv2.2016b) of ocean biogeochemical variables based on the new GLODAP version 2 data product (Olsen et al., 2016; Key et al., 2015), which covers all ocean basins over the years 1972 to 2013. The quality-controlled and internally consistent GLODAPv2 was used to create global 1° × 1° mapped climatologies of salinity, temperature, oxygen, nitrate, phosphate, silicate, total dissolved inorganic carbon (TCO2), total alkalinity (TAlk), pH, and CaCO3 saturation states using the Data-Interpolating Variational Analysis (DIVA) mapping method. Improving on maps based on an earlier but similar dataset, GLODAPv1.1, this climatology also covers the Arctic Ocean. Climatologies were created for 33 standard depth surfaces. The conceivably confounding temporal trends in TCO2 and pH due to anthropogenic influence were removed prior to mapping by normalizing these data to the year 2002 using first-order calculations of anthropogenic carbon accumulation rates. We additionally provide maps of accumulated anthropogenic carbon in the year 2002 and of preindustrial TCO2. For all parameters, all data from the full 1972–2013 period were used, including data that did not receive full secondary quality control. The GLODAPv2.2016b global 1° × 1° mapped climatologies, including error fields and ancillary information, are available at the GLODAPv2 web page at the Carbon Dioxide Information Analysis Center (CDIAC; doi:10.3334/CDIAC/OTG.NDP093_GLODAPv2).

  • Open Access English
    Authors: 
    Marle, Margreet J. E.; Kloster, Silvia; Magi, Brian I.; Marlon, Jennifer R.; Daniau, Anne-Laure; Field, Robert D.; Arneth, Almut; Forrest, Matthew; Hantson, Stijn; Kehrwald, Natalie M.; +7 more
    Country: Netherlands
    Project: EC | PEGASOS (265148), NSF | Collaborative Research: T... (1437074), EC | DE-CO2 (280061), NSF | Collaborative Research: T... (1436496), EC | BACCHUS (603445), EC | MACC-III (633080), EC | LUC4C (603542)

    Fires have influenced atmospheric composition and climate since the rise of vascular plants, and satellite data have shown the overall global extent of fires. Our knowledge of historic fire emissions has progressively improved over the past decades due mostly to the development of new proxies and the improvement of fire models. Currently, there is a suite of proxies including sedimentary charcoal records, measurements of fire-emitted trace gases and black carbon stored in ice and firn, and visibility observations. These proxies provide opportunities to extrapolate emission estimates back in time based on satellite data starting in 1997, but each proxy has strengths and weaknesses regarding, for example, the spatial and temporal extents over which they are representative. We developed a new historic biomass burning emissions dataset starting in 1750 that merges the satellite record with several existing proxies and uses the average of six models from the Fire Model Intercomparison Project (FireMIP) protocol to estimate emissions when the available proxies had limited coverage. According to our approach, global biomass burning emissions were relatively constant, with 10-year averages varying between 1.8 and 2.3 Pg C yr−1. Carbon emissions increased only slightly over the full time period and peaked during the 1990s after which they decreased gradually. There is substantial uncertainty in these estimates, and patterns varied depending on choices regarding data representation, especially on regional scales. The observed pattern in fire carbon emissions is for a large part driven by African fires, which accounted for 58 % of global fire carbon emissions. African fire emissions declined since about 1950 due to conversion of savanna to cropland, and this decrease is partially compensated for by increasing emissions in deforestation zones of South America and Asia. These global fire emission estimates are mostly suited for global analyses and will be used in the Coupled Model Intercomparison Project Phase 6 (CMIP6) simulations.

  • Other research product . Other ORP type . 2018
    Open Access English
    Authors: 
    Sabine, C. L.; Hankin, S.; Koyuk, H.; Bakker, D. C. E.; Pfeil, B.; Olsen, A.; Metzl, N.; Kozyr, A.; Fassbender, A.; Manke, A.; +66 more
    Publisher: Copernicus Publications
    Project: NSF | Support for International... (0938349), EC | CARBOCHANGE (264879), NSF | Support for the Intergove... (1068958)

    As a response to public demand for a well-documented, quality controlled, publically available, global surface ocean carbon dioxide (CO2) data set, the international marine carbon science community developed the Surface Ocean CO2 Atlas (SOCAT). The first SOCAT product is a collection of 6.3 million quality controlled surface CO2 data from the global oceans and coastal seas, spanning four decades (1968–2007). The SOCAT gridded data presented here is the second data product to come from the SOCAT project. Recognizing that some groups may have trouble working with millions of measurements, the SOCAT gridded product was generated to provide a robust, regularly spaced CO2 fugacity (fCO2) product with minimal spatial and temporal interpolation, which should be easier to work with for many applications. Gridded SOCAT is rich with information that has not been fully explored yet (e.g., regional differences in the seasonal cycles), but also contains biases and limitations that the user needs to recognize and address (e.g., local influences on values in some coastal regions).

  • Other research product . Other ORP type . 2013
    Open Access English
    Authors: 
    Chen, Xi; Dyer, Martin; Goldberg, Leslie Ann; Jerrum, Mark; Lu, Pinyan; McQuillan, Colin; Richerby, David;
    Publisher: Schloss Dagstuhl - Leibniz-Zentrum fur Informatik, Dagstuhl Publishing
    Countries: Germany, United Kingdom
    Project: NSF | EAGER: Social Information... (1139915)

    We study the complexity of approximation for a weighted counting constraint satisfaction problem #CSP(F). In the conservative case, where F contains all unary functions, a classification is known for the Boolean domain. We give a classification for problems with general finite domain. We define weak log-modularity and weak log-supermodularity, and show that #CSP(F) is in FP if F is weakly log-modular. Otherwise, it is at least as hard to approximate as #BIS, counting independent sets in bipartite graphs, which is believed to be intractable. We further sub-divide the #BIS-hard case. If F is weakly log-supermodular, we show that #CSP(F) is as easy as Boolean log-supermodular weighted #CSP. Otherwise, it is NP-hard to approximate. Finally, we give a trichotomy for the arity-2 case. Then, #CSP(F) is in FP, is #BIS-equivalent, or is equivalent to #SAT, the problem of approximately counting satisfying assignments of a CNF Boolean formula.

  • Other research product . Other ORP type . 2012
    Open Access English
    Authors: 
    Kohl, M.;
    Country: Germany
    Project: NSF | ZooGen, a DNA Sequence Da... (0003884), NSF | MRI-R2 Consortium: Develo... (0959521), NSF | OLYMPUS and TREK: Two Pre... (0855473), NSF | Exploring Fundamental Pro... (1207672)
  • Other research product . Other ORP type . 2012
    Open Access English
    Authors: 
    Kohl, M.;
    Country: Germany
    Project: NSF | ZooGen, a DNA Sequence Da... (0003884), NSF | MRI-R2 Consortium: Develo... (0959521), NSF | OLYMPUS and TREK: Two Pre... (0855473)
  • Other research product . Other ORP type . 2011
    Open Access
    Authors: 
    Hendricks, Stefan; Rabenstein, Lasse; Lehmann-Horn, J.; Nuber, A.; Eicken, H.; Mahoney, A.;
    Country: Germany
    Project: NSF | Collaborative research on... (0632130)
  • Other research product . Other ORP type . 2010
    Open Access
    Authors: 
    Cutter, G.; Andersson, P.; Codispoti, Lou; Croot, P.; François, R.; Lohan, M. C.; Obata, H.; Rutgers v. d. Loeff, Michiel;
    Publisher: GEOTRACES
    Country: Germany
    Project: NSF | The Panulirus (STATION S)... (8613904)

    The GEOTRACES Standards and Intercalibration (S&I) Committee is charged with ensuring that the data generated during GEOTRACES are as precise and accurate as possible, which includes all the steps from sampling to analysis. Thus, sampling methods for dissolved and particulate constituents must take a representative (of the water depth/water mass) and uncontaminated sample, the samples must be stored (or immediately analyzed) in a fashion that preserves the concentrations (activities) and chemical speciation, and the analyses of these samples must yield accurate data (concentration, activity, isotopic composition, chemical speciation). To this end, experiences from the 2008-2010 GEOTRACES Intercalibration Program, and other related intercalibration efforts, helped to create the protocols in this document. However, methods continually evolve and the GEOTRACES S&I Committee will monitor these advances as validated by intercalibrations and modify the methods as warranted. The protocols here are divided into trace element and isotope groups: Hydrography and Ancillary Parameters, Radioactive Isotopes, Radiogenic Isotopes, Trace Elements, and Nutrient Isotopes. Those who contributed to preparing these protocols are listed in Appendix 1 and are sincerely thanked for their efforts in helping GEOTRACES and the worldwide TEI community.

  • English
    Authors: 
    van Mooy, B. A. S.; Moutin, T.; Duhamel, S.; Rimmelin, P.; van Wambeke, France;
    Publisher: HAL CCSD
    Country: France
    Project: NSF | Sources and Biogeochemica... (0646944)

    International audience; Membrane lipid molecules are a major component of planktonic organisms and this is particularly true of the microbial picoplankton that dominate the open ocean; with their high surface-area to volume ratios, the synthesis of membrane lipids places a major demand on their overall cell metabolism. The synthesis of one class of membrane lipids, the phospholipids, also creates a demand for the nutrient phosphorus, and we sought to refine our understanding of the role of phospholipids in the upper ocean phosphorus cycle. We measured the rates of phospholipid synthesis in a transect of the eastern subtropical South Pacific from Easter Island to Concepcion, Chile as part of the BIOSOPE program. Our approach combined standard phosphorus radiotracer incubations and lipid extraction methods. We found that phospholipid synthesis rates varied from less than 1 to greater than 200 pmol P L-1 h-1, and that phospholipid synthesis contributed between less than 5% to greater than 22% of the total PO43- incorporation rate. Changes in the percentage that phospholipid synthesis contributed to total PO43- incorporation were strongly correlated with the ratio of primary production to bacterial production, which supported our hypothesis that heterotrophic bacteria were the primary agents of phospholipid synthesis. The spatial variation in phospholipid synthesis rates underscored the importance of heterotrophic bacteria in the phosphorus cycle of the eastern subtropical South Pacific, particularly the hyperoligotrophic South Pacific subtropical gyre.

  • Open Access
    Authors: 
    Knap, A. H.; Michaels, A.; Close, A. R.; Ducklow, H.; Dickson, A. G.;
    Country: Germany
    Project: NSF | The Panulirus (STATION S)... (8613904)
Advanced search in
Research products
arrow_drop_down
Searching FieldsTerms
Any field
arrow_drop_down
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Include:
10 Research products, page 1 of 1
  • Open Access English
    Authors: 
    Lauvset, Siv Kari; Key, Robert M.; Olsen, Are; van Heuven, Steven; Velo, Antón; Lin, Xiaohua; Schirnick, Carsten; Kozyr, Alex; Tanhua, Toste; Hoppema, Mario; +7 more
    Project: EC | SEADATANET II (283607), NSF | Support for International... (1243377), EC | CARBOCHANGE (264879), NSF | Southern Ocean Carbon and... (1425989), EC | AtlantOS (633211), NSF | Collaborative Research: C... (0825163)

    We present a mapped climatology (GLODAPv2.2016b) of ocean biogeochemical variables based on the new GLODAP version 2 data product (Olsen et al., 2016; Key et al., 2015), which covers all ocean basins over the years 1972 to 2013. The quality-controlled and internally consistent GLODAPv2 was used to create global 1° × 1° mapped climatologies of salinity, temperature, oxygen, nitrate, phosphate, silicate, total dissolved inorganic carbon (TCO2), total alkalinity (TAlk), pH, and CaCO3 saturation states using the Data-Interpolating Variational Analysis (DIVA) mapping method. Improving on maps based on an earlier but similar dataset, GLODAPv1.1, this climatology also covers the Arctic Ocean. Climatologies were created for 33 standard depth surfaces. The conceivably confounding temporal trends in TCO2 and pH due to anthropogenic influence were removed prior to mapping by normalizing these data to the year 2002 using first-order calculations of anthropogenic carbon accumulation rates. We additionally provide maps of accumulated anthropogenic carbon in the year 2002 and of preindustrial TCO2. For all parameters, all data from the full 1972–2013 period were used, including data that did not receive full secondary quality control. The GLODAPv2.2016b global 1° × 1° mapped climatologies, including error fields and ancillary information, are available at the GLODAPv2 web page at the Carbon Dioxide Information Analysis Center (CDIAC; doi:10.3334/CDIAC/OTG.NDP093_GLODAPv2).

  • Open Access English
    Authors: 
    Marle, Margreet J. E.; Kloster, Silvia; Magi, Brian I.; Marlon, Jennifer R.; Daniau, Anne-Laure; Field, Robert D.; Arneth, Almut; Forrest, Matthew; Hantson, Stijn; Kehrwald, Natalie M.; +7 more
    Country: Netherlands
    Project: EC | PEGASOS (265148), NSF | Collaborative Research: T... (1437074), EC | DE-CO2 (280061), NSF | Collaborative Research: T... (1436496), EC | BACCHUS (603445), EC | MACC-III (633080), EC | LUC4C (603542)

    Fires have influenced atmospheric composition and climate since the rise of vascular plants, and satellite data have shown the overall global extent of fires. Our knowledge of historic fire emissions has progressively improved over the past decades due mostly to the development of new proxies and the improvement of fire models. Currently, there is a suite of proxies including sedimentary charcoal records, measurements of fire-emitted trace gases and black carbon stored in ice and firn, and visibility observations. These proxies provide opportunities to extrapolate emission estimates back in time based on satellite data starting in 1997, but each proxy has strengths and weaknesses regarding, for example, the spatial and temporal extents over which they are representative. We developed a new historic biomass burning emissions dataset starting in 1750 that merges the satellite record with several existing proxies and uses the average of six models from the Fire Model Intercomparison Project (FireMIP) protocol to estimate emissions when the available proxies had limited coverage. According to our approach, global biomass burning emissions were relatively constant, with 10-year averages varying between 1.8 and 2.3 Pg C yr−1. Carbon emissions increased only slightly over the full time period and peaked during the 1990s after which they decreased gradually. There is substantial uncertainty in these estimates, and patterns varied depending on choices regarding data representation, especially on regional scales. The observed pattern in fire carbon emissions is for a large part driven by African fires, which accounted for 58 % of global fire carbon emissions. African fire emissions declined since about 1950 due to conversion of savanna to cropland, and this decrease is partially compensated for by increasing emissions in deforestation zones of South America and Asia. These global fire emission estimates are mostly suited for global analyses and will be used in the Coupled Model Intercomparison Project Phase 6 (CMIP6) simulations.

  • Other research product . Other ORP type . 2018
    Open Access English
    Authors: 
    Sabine, C. L.; Hankin, S.; Koyuk, H.; Bakker, D. C. E.; Pfeil, B.; Olsen, A.; Metzl, N.; Kozyr, A.; Fassbender, A.; Manke, A.; +66 more
    Publisher: Copernicus Publications
    Project: NSF | Support for International... (0938349), EC | CARBOCHANGE (264879), NSF | Support for the Intergove... (1068958)

    As a response to public demand for a well-documented, quality controlled, publically available, global surface ocean carbon dioxide (CO2) data set, the international marine carbon science community developed the Surface Ocean CO2 Atlas (SOCAT). The first SOCAT product is a collection of 6.3 million quality controlled surface CO2 data from the global oceans and coastal seas, spanning four decades (1968–2007). The SOCAT gridded data presented here is the second data product to come from the SOCAT project. Recognizing that some groups may have trouble working with millions of measurements, the SOCAT gridded product was generated to provide a robust, regularly spaced CO2 fugacity (fCO2) product with minimal spatial and temporal interpolation, which should be easier to work with for many applications. Gridded SOCAT is rich with information that has not been fully explored yet (e.g., regional differences in the seasonal cycles), but also contains biases and limitations that the user needs to recognize and address (e.g., local influences on values in some coastal regions).

  • Other research product . Other ORP type . 2013
    Open Access English
    Authors: 
    Chen, Xi; Dyer, Martin; Goldberg, Leslie Ann; Jerrum, Mark; Lu, Pinyan; McQuillan, Colin; Richerby, David;
    Publisher: Schloss Dagstuhl - Leibniz-Zentrum fur Informatik, Dagstuhl Publishing
    Countries: Germany, United Kingdom
    Project: NSF | EAGER: Social Information... (1139915)

    We study the complexity of approximation for a weighted counting constraint satisfaction problem #CSP(F). In the conservative case, where F contains all unary functions, a classification is known for the Boolean domain. We give a classification for problems with general finite domain. We define weak log-modularity and weak log-supermodularity, and show that #CSP(F) is in FP if F is weakly log-modular. Otherwise, it is at least as hard to approximate as #BIS, counting independent sets in bipartite graphs, which is believed to be intractable. We further sub-divide the #BIS-hard case. If F is weakly log-supermodular, we show that #CSP(F) is as easy as Boolean log-supermodular weighted #CSP. Otherwise, it is NP-hard to approximate. Finally, we give a trichotomy for the arity-2 case. Then, #CSP(F) is in FP, is #BIS-equivalent, or is equivalent to #SAT, the problem of approximately counting satisfying assignments of a CNF Boolean formula.

  • Other research product . Other ORP type . 2012
    Open Access English
    Authors: 
    Kohl, M.;
    Country: Germany
    Project: NSF | ZooGen, a DNA Sequence Da... (0003884), NSF | MRI-R2 Consortium: Develo... (0959521), NSF | OLYMPUS and TREK: Two Pre... (0855473), NSF | Exploring Fundamental Pro... (1207672)
  • Other research product . Other ORP type . 2012
    Open Access English
    Authors: 
    Kohl, M.;
    Country: Germany
    Project: NSF | ZooGen, a DNA Sequence Da... (0003884), NSF | MRI-R2 Consortium: Develo... (0959521), NSF | OLYMPUS and TREK: Two Pre... (0855473)
  • Other research product . Other ORP type . 2011
    Open Access
    Authors: 
    Hendricks, Stefan; Rabenstein, Lasse; Lehmann-Horn, J.; Nuber, A.; Eicken, H.; Mahoney, A.;
    Country: Germany
    Project: NSF | Collaborative research on... (0632130)
  • Other research product . Other ORP type . 2010
    Open Access
    Authors: 
    Cutter, G.; Andersson, P.; Codispoti, Lou; Croot, P.; François, R.; Lohan, M. C.; Obata, H.; Rutgers v. d. Loeff, Michiel;
    Publisher: GEOTRACES
    Country: Germany
    Project: NSF | The Panulirus (STATION S)... (8613904)

    The GEOTRACES Standards and Intercalibration (S&I) Committee is charged with ensuring that the data generated during GEOTRACES are as precise and accurate as possible, which includes all the steps from sampling to analysis. Thus, sampling methods for dissolved and particulate constituents must take a representative (of the water depth/water mass) and uncontaminated sample, the samples must be stored (or immediately analyzed) in a fashion that preserves the concentrations (activities) and chemical speciation, and the analyses of these samples must yield accurate data (concentration, activity, isotopic composition, chemical speciation). To this end, experiences from the 2008-2010 GEOTRACES Intercalibration Program, and other related intercalibration efforts, helped to create the protocols in this document. However, methods continually evolve and the GEOTRACES S&I Committee will monitor these advances as validated by intercalibrations and modify the methods as warranted. The protocols here are divided into trace element and isotope groups: Hydrography and Ancillary Parameters, Radioactive Isotopes, Radiogenic Isotopes, Trace Elements, and Nutrient Isotopes. Those who contributed to preparing these protocols are listed in Appendix 1 and are sincerely thanked for their efforts in helping GEOTRACES and the worldwide TEI community.

  • English
    Authors: 
    van Mooy, B. A. S.; Moutin, T.; Duhamel, S.; Rimmelin, P.; van Wambeke, France;
    Publisher: HAL CCSD
    Country: France
    Project: NSF | Sources and Biogeochemica... (0646944)

    International audience; Membrane lipid molecules are a major component of planktonic organisms and this is particularly true of the microbial picoplankton that dominate the open ocean; with their high surface-area to volume ratios, the synthesis of membrane lipids places a major demand on their overall cell metabolism. The synthesis of one class of membrane lipids, the phospholipids, also creates a demand for the nutrient phosphorus, and we sought to refine our understanding of the role of phospholipids in the upper ocean phosphorus cycle. We measured the rates of phospholipid synthesis in a transect of the eastern subtropical South Pacific from Easter Island to Concepcion, Chile as part of the BIOSOPE program. Our approach combined standard phosphorus radiotracer incubations and lipid extraction methods. We found that phospholipid synthesis rates varied from less than 1 to greater than 200 pmol P L-1 h-1, and that phospholipid synthesis contributed between less than 5% to greater than 22% of the total PO43- incorporation rate. Changes in the percentage that phospholipid synthesis contributed to total PO43- incorporation were strongly correlated with the ratio of primary production to bacterial production, which supported our hypothesis that heterotrophic bacteria were the primary agents of phospholipid synthesis. The spatial variation in phospholipid synthesis rates underscored the importance of heterotrophic bacteria in the phosphorus cycle of the eastern subtropical South Pacific, particularly the hyperoligotrophic South Pacific subtropical gyre.

  • Open Access
    Authors: 
    Knap, A. H.; Michaels, A.; Close, A. R.; Ducklow, H.; Dickson, A. G.;
    Country: Germany
    Project: NSF | The Panulirus (STATION S)... (8613904)
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