Abstract.A well-documented, publicly available, global data set of surface ocean carbon dioxide (CO 2 ) parameters has been called for by international groups for nearly two decades. The Surface Ocean CO 2 Atlas (SOCAT) project was initiated by the international marine carbon science community in 2007 with the aim of providing a comprehensive, publicly available, regularly updated, global data set of marine surface CO 2 , which had been subject to quality control (QC). Many additional CO 2 data, not yet made public via the Carbon Dioxide Information Analysis Center (CDIAC), were retrieved from data originators, public websites and other data centres. All data were put in a uniform format following a strict protocol. Quality control was carried out according to clearly defined criteria. Regional specialists performed the quality control, using state-of-the-art web-based tools, specially developed for accomplishing this global team effort. SOCAT version 1.5 was made public in September 2011 and holds 6.3 million quality controlled surface CO 2 data points from the global oceans and coastal seas, spanning four decades . Three types of data products are available: individual cruise files, a merged complete data set and gridded products. With the rapid expansion of marine CO 2 data collection and the importance of quantifying net global oceanic CO 2 uptake and its changes, sustained data synthesis and data access are priorities. Data coverage MotivationThe net absorption of CO 2 by the oceans, caused by rising atmospheric CO 2 concentrations since the industrial revolution, has been responsible for removing CO 2 equivalent to approximately 50 % of the fossil fuel and cement manufacturing emissions or about 30 % of the total anthropogenic emissions, including land use change (Sabine et al., 2004). Because of the availability of the carbonate ion, an important species of the dissolved inorganic carbon pool, and carbonate sediments, the oceans have a tremendous CO 2 uptake capacity and will, on timescales of ten to hundred thousand years, absorb all but a small fraction of the fossil CO 2 that has been and will be emitted (Archer et al., 1997). Meanwhile the changes in ocean CO 2 uptake, relying on factors such as ocean circulation and biology, will be among the decisive factors for the evolution of future atmospheric CO 2 concentrations and climate development (e.g., Friedlingstein et al., 2006;Riebesell et al., 2009). Presently there are two types of globally coordinated efforts that seek to resolve the dynamics of ocean CO 2 uptake through observations: repeat hydrography and surface ocean CO 2 observations (Gruber et al., 2010;Sabine et al., 2010). While repeat hydrography aims to assess variations in the ocean inventory of CO 2 on decadal timescales, surface ocean observations may resolve variations on seasonal to interannual timescales due to the higher sampling frequency. This high sampling frequency has been made possible by the advent of autonomous instruments and sensors for the nearcontinuous determination o...

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Pacific water, sea ice meltwater, and river water are the primary sources of freshwater in the Arctic Ocean. We have determined their relative fractions on a transect across the Arctic Ocean Section 2005 Expedition onboard IB Oden, which took place from 21 August to 23 September 2005. The transect began north of Alaska, continued through the central Canada Basin to the Alpha Ridge and into the Makarov Basin, and ended in Amundsen Basin. Pacific freshwater and river water were the major sources of freshwater throughout the central Canada Basin and into Makarov Basin, with river water fractions sometimes considerably higher than Pacific water in the top ∼50 m. Pacific freshwater extended to depths of about 200 m. Pacific water found over the Alpha Ridge and in the Amundsen Basin is suggested to have been transported there in the Transpolar Drift. The inventories of Pacific freshwater and river water were roughly constant along the section through most of the Canada and Makarov basins. River water fractions were greater than those of Pacific freshwater in the Amundsen Basin. Sea ice meltwater fractions were negative (reflecting net ice formation) or near zero throughout most of the section. A comparison of freshwater inventories with those at stations occupied during expeditions in 1991, 1994, and 1996 indicated an increase in river water inventories in the Makarov and Amundsen basins on the Eurasian side of the Arctic Ocean.

Recibidü en marzo de 1999. aceptado en ~e~i r e m b r e de i999 ABSTRACTSeawater was sarnpled from different depths in the North Atlantic Ocean (Canary Islands region) and distributed among three different labs for the determination of titration alkalinity. Analysis was performed by potentiornetric rnethods. involving titration in a closed cell, titration in an open cell and a two end-point acid addition method. The precisíon, which is the sarnple reproducibility taken from the mean sranaarci aeviarion Íor repiicate measurements, was ~erween 0.45 anci 0.90 prnoi icg-' for ine individual labs. Accuracy, here taken as the deviation for the values of a lab from the rnean of al1 three, was mostly below 1 pmol -kg-' and never exceeded O. 1% of the sarnple value. Mean standard deviation for al1 labs and al1 sarnples was 0.87 prnol . kg-', once the individual methods were calibrated using Ciencias Marinas, Vol. 26, No. 1,2000 certified reference material (CRM). Without CRM calibration, the mean standard deviation would increase to 2.8 p n o l . kg-'. The conclusion is that current high precision rnethods for alkalinity measurements calibrated with CRMs are able to reach similar accuracy as the measurement of total dissolved inorganic carbon by coulornetry and therefore allow for the precise determination of the oceanic carbon dioxide system by using the two measured parameters.Key words: alkalinity, potentiometry, seawater, certified reference material RESUMEN Se determinó la alcalinidad de muestras de agua de mar recogidas a diferentes profundidades en el Océano Atlántico Norte y distribuidas entre tres laboratorios, utilizando tres variantes potenciométricas: valoración en cubeta cerrada, valoración en cubeta abierta y un método de adición a doble punto final. La precisión, la reproducibilidad de la muestra obtenida a partir de la desviación estándar media para medidas replicadas, fue entre 0.45 y 0.90 p o l . kg-' para cada laboratorio. La exactitud, tomada como la desviación de los valores de un laboratorio respecto de la media de los tres, fue mayoritariamente menor que 1 pmol . kg-' y nunca excedió 0.1% del valor de la muestra. La desviación media estándar para todos los laboratorios y todas las muestras fue de 0.87 pmol . kg-', una vez que los métodos individuales se calibraron usando material certificado de referencia (CRM). Sin la calibración con CRM, la desviación estándar media se incrementaria a 2.8 pmol . kg-'. Se concluye que la precisión real de los métodos para la medida de la alcalinidad calibrada con CRM es capaz de alcanzar exactitudes similares a las medidas de carbono inorgánico total por coulometría y por lo tanto permite la determinación precisa del sistema de carbono oceánico usando la medida de las dos variables.Palabras clave: alcalinidad, potenciometría, agua de mar, material certificado de referencia.

Abstract. The original goal of the CARINA (Carbon in Atlantic Ocean) data synthesis project was to create a merged calibrated data set from open ocean subsurface measurements by European scientists that would be generally useful for biogeochemical investigations in the North Atlantic and in particular, studies involving the carbon system. Over time the geographic extent expanded to include the entire Atlantic, the Arctic and the Southern Ocean and the international collaboration broadened significantly. In this paper we give a brief history of the project, a general overview of data included and an outline of the procedures used during the synthesis. The end result of this project was a set of 3 data products, one for each of the listed ocean regions. It is critical that anyone who uses any of the CARINA data products recognize that the data products are not simply concatenations of the originally measured values. Rather, the data have been through an extensive calibration procedure designed to remove measurement bias and bad data. Also a significant fraction of the individual values in the data products were derived either by direct calculation or some means of approximation. These data products were constructed for basin scale biogeochemical investigations and may be inappropriate for investigations involving small areal extent or similar detailed analyses. More information on specific parts of this project can be found in companion articles in this issue. In particular, Tanhua et al. (2009) and Tanhua (2009) describe the procedures and software used to remove measurement bias from the original data. The three data products and a significant volume of supporting information are available from the CARINA web site hosted by the Carbon Dioxide Information Analysis Center (CDIAC: http://cdiac.esd.ornl.gov/oceans/CARINA/Carina_inv.html). Anyone wanting to use the data is advised to get the highest version number of each data product. Incremental versions represent either corrections or additions. The web site documents specifics of the changes.