The fugacity of CO 2 in surface water (fCO 2w ) was measured in the eastern equatorial Pacific (EEP) during the boreal spring and fall of 1992 and in the spring of 1993. A prolonged El Niño occurred during this period with anomalously warm sea surface temperatures (SST) during the spring of 1992 and 1993. Correspondingly, the fCO 2w values were lower than historical non‐El Niño values at the equator. However, the fCO 2w in the spring of 1993 was up to 50 µatm higher than in the spring of 1992, despite similar SSTs. The trend is attributed to the slower response times of factors causing fCO 2w decrease compared to rapid increase of fCO 2w by upwelling of cold water with high carbon content and subsequent heating. During the fall of 1992, SSTs south of the equator were 5°C cooler than in the spring, which is indicative of vigorous upwelling of water with high CO 2 content from below the thermocline. Decreases in fCO 2w due to net biological productivity and gas exchange take of the order of months, causing the fCO 2w levels during the spring of 1993 to be elevated compared to the spring of the previous year. Our data and data obtained in 1986 and 1989 along 110°W suggest that fCO 2 maxima in the equatorial Pacific can be either associated with temperature minima or temperature maxima. Despite the multitude of factors which influence fCO 2w , most of the variance can be accounted for with changes in nitrate and SST. A multilinear regression of fCO 2w with SST and nitrate for the 1992 data has a standard error in predicted fCO 2w of 10 µatm. Air‐sea fluxes of CO 2 in the EEP were estimated to be 30% higher in the spring of 1993 and 10% higher in the fall of 1992 than in the spring of 1992.
Abstract. The Surface Ocean CO2 Atlas (SOCAT) is a synthesis of quality-controlled fCO2 (fugacity of carbon dioxide) values for the global surface oceans and coastal seas with regular updates. Version 3 of SOCAT has 14.7 million fCO2 values from 3646 data sets covering the years 1957 to 2014. This latest version has an additional 4.6 million fCO2 values relative to version 2 and extends the record from 2011 to 2014. Version 3 also significantly increases the data availability for 2005 to 2013. SOCAT has an average of approximately 1.2 million surface water fCO2 values per year for the years 2006 to 2012. Quality and documentation of the data has improved. A new feature is the data set quality control (QC) flag of E for data from alternative sensors and platforms. The accuracy of surface water fCO2 has been defined for all data set QC flags. Automated range checking has been carried out for all data sets during their upload into SOCAT. The upgrade of the interactive Data Set Viewer (previously known as the Cruise Data Viewer) allows better interrogation of the SOCAT data collection and rapid creation of high-quality figures for scientific presentations. Automated data upload has been launched for version 4 and will enable more frequent SOCAT releases in the future. High-profile scientific applications of SOCAT include quantification of the ocean sink for atmospheric carbon dioxide and its long-term variation, detection of ocean acidification, as well as evaluation of coupled-climate and ocean-only biogeochemical models. Users of SOCAT data products are urged to acknowledge the contribution of data providers, as stated in the SOCAT Fair Data Use Statement. This ESSD (Earth System Science Data) "living data" publication documents the methods and data sets used for the assembly of this new version of the SOCAT data collection and compares these with those used for earlier versions of the data collection (Pfeil et al., 2013; Sabine et al., 2013; Bakker et al., 2014). Individual data set files, included in the synthesis product, can be downloaded here: doi:10.1594/PANGAEA.849770. The gridded products are available here: doi:10.3334/CDIAC/OTG.SOCAT_V3_GRID.
Abstract. The Surface Ocean CO2 Atlas (SOCAT) is a synthesis of quality-controlled fCO2 (fugacity of carbon dioxide) values for the global surface oceans and coastal seas with regular updates. Version 3 of SOCAT has 14.5 million fCO2 values from 3646 data sets covering the years 1957 to 2014. This latest version has an additional 4.4 million fCO2 values relative to version 2 and extends the record from 2011 to 2014. Version 3 also significantly increases the data availability for 2005 to 2013. SOCAT has an average of approximately 1.2 million surface water fCO2 values per year for the years 2006 to 2012. Quality and documentation of the data has improved. A new feature is the data set quality control (QC) flag of E for data from alternative sensors and platforms. The accuracy of surface water fCO2 has been defined for all data set QC flags. Automated range checking has been carried out for all data sets during their upload into SOCAT. The upgrade of the interactive Data Set Viewer (previously known as the Cruise Data Viewer) allows better interrogation of the SOCAT data collection and rapid creation of high-quality figures for scientific presentations. Automated data upload has been launched for version 4 and will enable more frequent SOCAT releases in the future. High-profile scientific applications of SOCAT include quantification of the ocean sink for atmospheric carbon dioxide and its long-term variation, detection of ocean acidification, as well as evaluation of coupled-climate and ocean-only biogeochemical models. Users of SOCAT data products are urged to acknowledge the contribution of data providers, as stated in the SOCAT Fair Data Use Statement. This ESSD (Earth System Science Data) "Living Data" publication documents the methods and data sets used for the assembly of this new version of the SOCAT data collection and compares these with those used for earlier versions of the data collection (Pfeil et al., 2013; Sabine et al., 2013; Bakker et al., 2014).
The principle, application, and assessment of the membrane‐based ProOceanus CO 2 ‐Pro sensor for partial pressure of CO 2 (pCO 2 ) are presented. The performance of the sensor is evaluated extensively under field and laboratory conditions by comparing the sensor outputs with direct measurements from calibrated pCO 2 measuring systems and the thermodynamic carbonate calculation of pCO 2 from discrete samples. Under stable laboratory condition, the sensor agreed with a calibrated water‐air equilibrator system at −3.0 ± 4.4 µatm during a 2‐month intercomparison experiment. When applied in field deployments, the larger differences between measurements and the calculated pCO 2 references (6.4 ± 12.3 µatm on a ship of opportunity and 8.7 ± 14.1 µatm on a mooring) are related not only to sensor error, but also to the uncertainties of the references and the comparison process, as well as changes in the working environments of the sensor. When corrected against references, the overall uncertainties of the sensor results are largely determined by those of the pCO 2 references (± 2 and ± 8 µatm for direct measurements and calculated pCO 2 , respectively). Our study suggests accuracy of the sensor can be affected by temperature fluctuations of the detector optical cell and calibration error. These problems have been addressed in more recent models of the instrument through improving detector temperature control and through using more accurate standard gases. Another interesting result in our laboratory test is the unexpected change in alkalinity which results in significant underestimation in the pCO 2 calculation as compared to the direct measurement (up to 90 µatm).
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