An evaluation of tracer fields and anthropogenic carbon in the equatorial and the tropical North Atlantic

The transit time distribution method was applied to dichlorodifluoromethane and sulfur hexafluoride measurements from four cruises to the tropical North Atlantic between 2006 and 2009 in order to estimate anthropogenic carbon (C-ant) concentrations. By assuming an Inverse Gaussian distribution of the transit time distribution the best fit to the data was achieved with the ratio of mean age to width equals 1. Significant differences in the mean age and C-ant concentrations between the equatorial belt (5 degrees S-5 degrees N) and the Guinea dome area (5 degrees-15 degrees N) was found. Mean ages are higher and C-ant concentrations are lower in the Guinea dome area than at same depths, or densities, in the equatorial belt. The mean column inventories in the upper 1200 m are higher by about 3 mol m(-2) in the equatorial belt compared to the Guinea dome area. The mean column inventory of C-ant, for the whole water column, in the tropical Atlantic is 32.2 mol m(-2) (error range: 30.6-45.2 mol m(-2)), which is significantly lower than the previous estimates. The total C-ant inventory in the eastern tropical Atlantic is 2.5 Pg (error range: 2.3-3.5 Pg) for an area of 6 x 10(6) km(2), comprising the Guinea dome region and the equatorial belt. The equatorial belt has 40% higher storage of C-ant compared to the Guinea dome area which reflects the occurrence of relatively young deep waters at the equator, being high in anthropogenic carbon. Our tracer based C-ant estimates were compared to C-ant concentrations calculated with the TrOCA method applied to measurements conducted in 1999. The TrOCA based estimates are significantly higher than our tracer based C-ant estimates. Comparison between tracer measurements in 1999 and the 2006-2009 time-frame revealed possible speed-up of ventilation in the upper water column, increasing the C-ant concentration in this depth range at a faster rate and a C-ant increase of 12.1 mu mol kg(-1) in the tropical surface water was foun

Ventilation of the Arctic Ocean: Mean ages and inventories of anthropogenic CO2 and CFC-11

The Arctic Ocean constitutes a large body of water that is still relatively poorly surveyed because of logistical difficulties, although the importance of the Arctic Ocean for global circulation and climate is widely recognized. For instance, the concentration and inventory of anthropogenic CO2 (C ant) in the Arctic Ocean are not properly known despite its relatively large volume of well-ventilated waters. In this work, we have synthesized available transient tracer measurements (e.g., CFCs and SF6) made during more than two decades by the authors. The tracer data are used to estimate the ventilation of the Arctic Ocean, to infer deep-water pathways, and to estimate the Arctic Ocean inventory of C ant. For these calculations, we used the transit time distribution (TTD) concept that makes tracer measurements collected over several decades comparable with each other. The bottom water in the Arctic Ocean has CFC values close to the detection limit, with somewhat higher values in the Eurasian Basin. The ventilation time for the intermediate water column is shorter in the Eurasian Basin (∼200 years) than in the Canadian Basin (∼300 years). We calculate the Arctic Ocean C ant inventory range to be 2.5 to 3.3 Pg-C, normalized to 2005, i.e., ∼2% of the global ocean C ant inventory despite being composed of only ∼1% of the global ocean volume. In a similar fashion, we use the TTD field to calculate the Arctic Ocean inventory of CFC-11 to be 26.2 ± 2.6 × 106 moles for year 1994, which is ∼5% of the global ocean CFC-11 inventor

Use of SF6 to estimate anthropogenic CO2 in the upper ocean

The highest concentrations of anthropogenic carbon (C_ant) are found in the upper layers of the world ocean. However, this is where seasonal variability of inorganic carbon and related parameters due to thermal and biological effects complicates use of back-calculation approaches for C ant . Tracer based approaches to C_ant estimation are unaffected by biological variability and have found wide application. However, slow-down, even reversal, of the atmospheric growth of chlorofluorocarbons (CFCs) restricts use of these tracers for C ant estimation for waters ventilated since the mid 1990s. Here we apply SF6, a tracer that continues to increase in the atmosphere, as a basis for the C_ant estimation, using samples collected in the midlatitude North Atlantic in 2004. C ant estimates derived from water mass transit time distributions (TTDs) calculated with SF6 are compared to those based on CFC-12. For recently ventilated waters (pCFC-12 > ∼450 ppt), the uncertainty of SF6 based estimates of C_ant is ∼6 μmol kg−1 less than that of CFC-12 based estimates. CFC-12 based estimates remain more reliable for older (deeper) water masses, as a result of the longer input history and more readily detectable concentrations of CFC-12. Historical data suggest that the near-surface saturation of CFC-12 has increased over time, in inverse proportion to its atmospheric growth rate. Use of a time-dependent saturation of CFC-12 in TTD calculations appears to provide more reliable estimation of C_ant

Anthropogenic carbon distribution in the eastern South Pacific Ocean

We present results of the CO(2)/carbonate system from the BIOSOPE cruise in the Eastern South Pacific Ocean, in an area not sampled previously. In particular, we present estimates of the anthropogenic carbon (C(ant)(TrOCA)) distribution in the upper 1000m of this region using the TrOCA method. The highest concentrations of C(ant)(TrOCA) found around 13 degrees S, 132 degrees W and 32 degrees S, 91 degrees W, are higher than 80 mu mol.kg(-)1 and 70 mu mol.kg(-1), respectively. The lowest concentrations are observed below 800m depth (<= 2 mu mol.kg(-1)) and within the Oxygen Minimum Zone (OMZ), mainly around 140 degrees W (< 11 mu mol.kg(-1)). As a result of the anthropogenic carbon penetration there has been decrease in pH by over 0.1 on an average in the upper 200 m. This work further improves our understanding on the penetration of anthropogenic carbon in the Eastern Pacific Ocean

Ocean Acidification and Long‐Term Changes in the Carbonate System Properties of the South Atlantic Ocean

The wind-driven part of the South Atlantic Ocean is primarily ventilated through central and intermediate water formation. Through the water mass formation processes, anthropogenic carbon (C-ant) is introduced into the ocean's interior which in turn makes the South Atlantic region vulnerable to ocean acidification. C-ant and the accompanying acidification effects have been estimated for individual sections in the region since the 1980s but a comprehensive synthesis for the entire basin is still lacking. Here, we quantified the C-ant accumulation rates and examined the changes in the carbonate system properties for the South Atlantic using a modified extended multiple linear regression method applied to five hydrographic sections and data from the GLODAPv2.2021 product. From 1989 to 2019, a mean C-ant column inventory change of 0.94 +/- 0.39 mol C m(-2) yr(-1) was found. C-ant accumulation rates of 0.89 +/- 0.33 mu mol kg(-1) yr(-1) and 0.30 +/- 0.29 mu mol kg(-1) yr(-1) were observed in central and intermediate waters, accompanied by acidification rates of -0.0020 +/- 0.0007 pH units yr(-1) and -0.0009 +/- 0.0009 pH units yr(-1), respectively. Furthermore, increased remineralization was observed in intermediate waters, amplifying the acidification of this water mass, especially at the African coast along 25 degrees S. This increase in remineralization is likely related to circulation changes and increased biological activity nearshore. Assuming no changes in the observed trends, South Atlantic intermediate waters will become unsaturated with respect to aragonite in similar to 30 years, while the central water of the eastern margins will become unsaturated in similar to 10 years

A Sustainability Disclosure Index Using Corporate Sustainability Reports

Background: There are already many indices such as Bloomberg’s environmental-and-social governance (ESG) ratings and the Dow Jones Sustainability Indices (DSJI), which use proprietary methods to rate companies using private and publicly available information processed with proprietary methods. This paper seeks to develop a formative index for researchers and practitioners using only publicly available sustainability reports with a transparent procedure. Methods: Thirty-two indicators, obtained in an earlier study from the literature, GRI, and other sources, were adopted. The sustainability report of each of 331 companies was then scored on a discrete 0–3 scale for each indicator as regards disclosure. The index for the company then is simply a summation of the indicator scores. Tests were conducted to see if the index can be (a) used for companies with different revenues and from different sectors and (b) tested for explaining DJSI or ESG ratings. Results: The index can be used for companies with a wide range of revenues and from different sectors. Despite its simplicity, the disclosure index significantly explains the DJSI and ESG. Conclusions: A disclosure index for companies has been developed here using only their publicly available sustainability reports, unlike existing indices like the DJSI that use public and private information and proprietary methods. Researchers and financial institutions can use this index or develop their own indices by refining the methodology presented here

Unifying Markov Properties for Graphical Models

Several types of graphs with different conditional independence interpretations --- also known as Markov properties --- have been proposed and used in graphical models. In this paper we unify these Markov properties by introducing a class of graphs with four types of edges --- lines, arrows, arcs, and dotted lines --- and a single separation criterion. We show that independence structures defined by this class specialize to each of the previously defined cases, when suitable subclasses of graphs are considered. In addition, we define a pairwise Markov property for the subclass of chain mixed graphs which includes chain graphs with the LWF interpretation, as well as summary graphs (and consequently ancestral graphs). We prove the equivalence of this pairwise Markov property to the global Markov property for compositional graphoid independence models.Comment: 31 Pages, 6 figures, 1 tabl

Markov properties for mixed graphs

In this paper, we unify the Markov theory of a variety of different types of graphs used in graphical Markov models by introducing the class of loopless mixed graphs, and show that all independence models induced by $m$-separation on such graphs are compositional graphoids. We focus in particular on the subclass of ribbonless graphs which as special cases include undirected graphs, bidirected graphs, and directed acyclic graphs, as well as ancestral graphs and summary graphs. We define maximality of such graphs as well as a pairwise and a global Markov property. We prove that the global and pairwise Markov properties of a maximal ribbonless graph are equivalent for any independence model that is a compositional graphoid.Comment: Published in at http://dx.doi.org/10.3150/12-BEJ502 the Bernoulli (http://isi.cbs.nl/bernoulli/) by the International Statistical Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm

Variance Analysis of Basis Weight Variation on the Pilot Machine

The purpose of this study was to determine the significance of the variations of the pilot machine of the Department of Paper Science and Engineering at Western Michigan University by variance analysis conducted on basis weight profiles obtained from the Industrial Nucleonics scanning basis weight gauge. The profiles obtained from the basis weight gauge were subjected to a computer program which computed the cross-direction, machine-direction, and random component variations and determined F-ratios. The F-ratio shows the significance of the component variation. Cross-direction variation was found to decrease with speed. Machine-direction variation showed no significant trend and the random variation decreased with speed. It was found that the F-ratio comparing the machine-direction component to the random component was significant at the one per cent confidence level and should be lessened if better operational efficiency for the pilot machine is desired