A uniform, quality controlled Surface Ocean CO<sub>2</sub> Atlas (SOCAT)

Abstract

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...

Seasonal to decadal variations of sea surface pCO2 and sea‐air CO2 flux in the equatorial oceans over 1984–2013: A basin‐scale comparison of the Pacific and Atlantic Oceans

“…We also conduct direct model-data comparisons, by sampling model pCO 2 , using the SOCAT-gridded monthly data grids [Pfeil et al, 2013]. Figure 1 shows the averages/climatology over the period of 1984-2011.…”

“…We first use the SOCAT-gridded climatology [Pfeil et al, 2013] to evaluate model simulation. As shown in Table 2, the correlation coefficients are similar (ranging from 0.53 to 0.67) across the annual cycle for the tropical Pacific but vary considerably for the tropical Atlantic (0.32-0.83).…”

“…In particular, a monthly global climatology of sea-minus-atmosphere pCO 2 (ΔpCO 2 ) was constructed from approximately 3 million data points [Takahashi et al, 2009]. More recently, with an expansion of quality-controlled surface pCO 2 data, a merged complete data set and gridded products are made available [Pfeil et al, 2013]. Consequently, there have been a few approaches using these products to determine the interannual variability of sea surface pCO 2 (or ΔpCO 2 ) and/or oceanatmosphere CO 2 flux [e.g., Park et al, 2010;Rodenbeck et al, 2014].…”

“…The model faithfully reproduces the general features of phytoplankton dynamics in the equatorial surface waters of these two oceans [Wang et al, 2009[Wang et al, , 2013. This study consists of model validations of sea surface pCO 2 and air-sea CO 2 flux, using available data, including the latest Surface Ocean CO 2 Atlas (SOCAT) [Pfeil et al, 2013]. The objectives of this study are to assess the similarities and differences in the carbon fields between the tropical Pacific and Atlantic Oceans for the past three decades and to explore the underlying mechanisms regulating the sea surface pCO 2 and air-sea CO 2 flux across these two tropical basins.…”

A high-frequency atmospheric and seawater <i>p</i>CO<sub>2</sub> data set from 14 open-ocean sites using a moored autonomous system

“…Data are quality-controlled and flagged according to the SOCAT guidelines (Pfeil et al, 2013). For pCO 2 mooring purposes, we use three quality flags (QFs): a flag value of 2 represents an acceptable measurement, 3 is a questionable measurement, and 4 is a bad measurement.…”