An internally consistent dataset of &amp;lt;i&amp;gt;δ&amp;lt;/i&amp;gt;&amp;lt;sup&amp;gt;13&amp;lt;/sup&amp;gt;C-DIC in the North Atlantic Ocean – NAC13v1

Meike Becker,Matthew P Humphreys,Nils Andersen,Toste Tanhua,Arne Körtzinger,Helmut Erlenkeuser

doi:10.5194/essd-8-559-2016

Abstract

Abstract. The stable carbon isotope composition of dissolved inorganic carbon (δ13C-DIC) can be used to quantify fluxes within the carbon system. For example, knowing the δ13C signature of the inorganic carbon pool can help in describing the amount of anthropogenic carbon in the water column. The measurements can also be used for evaluating modeled carbon fluxes, for making basin-wide estimates of anthropogenic carbon, and for studying seasonal and interannual variability or decadal trends in interior ocean biogeochemistry. For all these purposes, it is not only important to have a sufficient amount of data, but these data must also be internally consistent and of high quality. In this study, we present a δ13C-DIC dataset for the North Atlantic which has undergone secondary quality control. The data originate from oceanographic research cruises between 1981 and 2014. During a primary quality control step based on simple range tests, obviously bad data were flagged. In a second quality control step, biases between measurements from different cruises were quantified through a crossover analysis using nearby data of the respective cruises, and values of biased cruises were adjusted in the data product. The crossover analysis was possible for 24 of the 32 cruises in our dataset, and adjustments were applied to 11 cruises. The internal accuracy of this dataset is 0.017 ‰. The dataset is available via the Carbon Dioxide Information Analysis Center (CDIAC) at http://cdiac.ornl.gov/oceans/ndp_096/NAC13v1.html, doi:10.3334/CDIAC/OTG.NAC13v1.

Highlights

Stable carbon isotope ratios are utilized as a tracer in several applications in marine carbon research
We present a δ13C-DIC dataset for the North Atlantic which has undergone secondary quality control
By observing the temporal development of the lightening of the inorganic carbon pool due to the uptake of CO2 originating from the burning of 13C-depleted fossil fuel carbon, a phenomenon known as the oceanic 13C Suess effect, an estimation of the anthropogenic carbon fraction of DIC is possible (Gruber et al, 2002; Körtzinger et al, 2003; Olsen et al, 2006; Olsen and Ninnemann, 2010; Quay et al, 2007; Racapé et al, 2013)

Summary

Introduction

Stable carbon isotope ratios are utilized as a tracer in several applications in marine carbon research. Databases like GLODAP (Global Ocean Data Analysis Project) and CARINA (Carbon dioxide in the Atlantic Ocean) were created for carbonrelated parameters (Olsen et al, 2016). These projects assembled the data and conducted a secondary quality control (QC) so that systematic biases between individual cruises could be identified and adjusted for (Tanhua et al, 2009; Velo et al, 2009; Tanhua et al, 2010a; Pierrot et al., 2010). Several new cruises have become available for the North Atlantic so that the present crossover study could be performed for this area. Care should be exercised for calculating Cant accumulation in water below 1500 m

Data provenance and structure

Apr–19 Oct 1981

Computational analysis

Adjustments

Conclusions