A multi-decade record of high quality fCO2 data in version 3 of the Surface Ocean CO2 Atlas (SOCAT)

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

Spatio-Temporal Trend of Past and Future Extreme Wave Climates in the Gulf of Guinea Driven by Climate Change

This study assessed the extremes of wave conditions for past (1979–2005) and future (2026–2045 and 2081–2100) time slices in the Gulf of Guinea (GoG). The ensemble produced from eight General Circulation Models under different Representative Concentration Pathway (RCP) emission scenarios (RCP4.5 and RCP8.5) was subjected to linear regression analysis and Mann–Kendal test for their trends and significance, respectively. Results showed an increase in the extreme of significant wave height (Hs) and mean wave period (Tm) between 1979–2005, 2026–2045, and 2081–2100 with few exceptions. The average values of annual and seasonal Hs and Tm range from 1.26–1.62 m and 10.37 s–10.86 s, respectively, for 1979–2005. These Hs values are projected to increase by 0.1 m (0.05 m) to 1.72 m (1.67 m) and the Tm will increase by 0.29 s (0.24 s) to 11.15 s (11.10 s) by the end of the century (mid-century) time slices, respectively. The mean wave direction (Dm) (201.89°–206.27°) showed an anticlockwise shift (−29.2 × 10−3 degrees per year) for 1979–2005 which is projected to become more southwesterly with an increase up to 2.2° (0.5°) by end (mid) century in 2100 (2045), respectively. Future work will be on the impacts of changing wave on longshore sediment transport along the GoG

Spatio-Temporal Trend of Past and Future Extreme Wave Climates in the Gulf of Guinea Driven by Climate Change

This study assessed the extremes of wave conditions for past (1979–2005) and future (2026–2045 and 2081–2100) time slices in the Gulf of Guinea (GoG). The ensemble produced from eight General Circulation Models under different Representative Concentration Pathway (RCP) emission scenarios (RCP4.5 and RCP8.5) was subjected to linear regression analysis and Mann–Kendal test for their trends and significance, respectively. Results showed an increase in the extreme of significant wave height (Hs) and mean wave period (Tm) between 1979–2005, 2026–2045, and 2081–2100 with few exceptions. The average values of annual and seasonal Hs and Tm range from 1.26–1.62 m and 10.37 s–10.86 s, respectively, for 1979–2005. These Hs values are projected to increase by 0.1 m (0.05 m) to 1.72 m (1.67 m) and the Tm will increase by 0.29 s (0.24 s) to 11.15 s (11.10 s) by the end of the century (mid-century) time slices, respectively. The mean wave direction (Dm) (201.89°–206.27°) showed an anticlockwise shift (−29.2 × 10−3 degrees per year) for 1979–2005 which is projected to become more southwesterly with an increase up to 2.2° (0.5°) by end (mid) century in 2100 (2045), respectively. Future work will be on the impacts of changing wave on longshore sediment transport along the GoG

A comparative study of total alkalinity and total inorganic carbon near tropical Atlantic coastal regions

This paper is based on a comparison of the carbon parameters at the western and eastern borders of the tropical Atlantic using data collected from 55 cruises. Oceanic and coastal data, mainly total alkalinity (TA), total dissolved inorganic carbon (CT), sea surface salinity (SSS) and sea surface temperature (SST), were compiled from different sources. These data were subdivided into three subsets: oceanic data, coastal data and adjacent to the Brazilian (western) and African coastal areas (eastern) data. Significant differences between the TA data (2099.4 ± 286.4 µmol kg−1) at the western and eastern edges (2198 ± 141.9 µmol kg−1) were observed. Differences in the CT values between the western edge (1779.6 ± 236.4 µmol kg−1) and eastern edge (1892.2 ± 94.2 µmol kg−1) were also noted. This pattern was due to the different variabilities in the carbon parameters between the eastern and western border coastal areas and to the biogeochemistry that drives these parameters. In the western coastal area, the physical features of the continental carbon and oceanic waters mixing with the freshwater that flows from the Amazon and Orinoco Rivers to the South American coast are different than the physical features of the water that flows from the Congo, Volta and Niger Rivers in the eastern region. Applying the TA empirical relationship to TA with values of SSS < 35 in the western and eastern regions leads to a higher root mean square error (rmse) in the eastern and western regions. Therefore, most of the existing TA empirical relationships are most useful at the regional scale due to the difference in the water properties of each region. The relationships of TA and CT determined in the western and eastern regions do not reproduce in situ data well, especially at the adjacent edges. This difference is explained by the difference between the African and Brazilian coasts in terms of their carbon parameter characteristics and processes responsible for their variation. Based on the mixing model, it has been shown that the primary productivity in the eastern region is higher than that in the western region. This is one of the reasons why the carbon parameters are higher in the eastern region. For each region studied, an equation for TA is introduced in this study

Beach Response to Wave Forcing from Event to Inter-Annual Time Scales at Grand Popo, Benin (Gulf of Guinea)

This paper assesses the morphological storm-event impact, seasonal cycles, trends of wave forcing, and beach’s response at the coastal area of Grand Popo, Benin. Three and a half years’ worth of data were collected from 2013 to 2016, using a video system calibrated with field data collected during a 10 day experiment. A comparison was carried out with Wavewatch III IOWAGA wave hindcast data. The along-shore-averaged shoreline position exhibited a seasonal pattern, which was related more to the average wave height than the average storm intensity. Storms occur in austral winter (June, July, August, and September). Based on 12 storms, the results revealed that the average storm duration was 1.6 days, with a mean erosion of 3.1 m. The average post-storm beach recovery duration was 15 days, and the average recovery rate was 0.4 m/day. The impact of storms was more or less amplified depending on the eroding and accreting periods of the wave climate. There was an inter-annual eroding trend of about −1.6 m/year, but the causes of this trend could not be explained

Coastal Zone Changes in West Africa: Challenges and Opportunities for Satellite Earth Observations

International audienceThe West African coastal population and ecosystems are increasingly exposed to a multitude of hazards. These are likely to be exacerbated by global climate change and direct impacts from local human activities. Our ability to understand coastal changes has been limited by an incomplete understanding of the processes and the difficulty of obtaining detailed data. Recent advances in satellite techniques have made it possible to obtain rich coastal data sets that provide a solid foundation for improving climate change adaptation strategies for humanity and increasing the resilience of ecosystems for sustainable development. In this article, we review West African coastal layout and current socio-environmental challenges together with key parameters that can be monitored and several coastal management programs that rely on satellite techniques to monitor indicators at the regional level. The social, technical and scientific problems and difficulties that hinder the interest of coastal practitioners and decision-makers to use the satellite data are identified. We provide a roadmap to precisely respond to these difficulties and on how an improved satellite earth observation strategy can better support future coastal zone management in West Africa

Stratospheric Sulfate Aerosols Impacts on West African Monsoon Precipitation Using GeoMIP Models

Abstract Stratospheric Aerosol Geoengineering (SAG) is proposed to offset global warming; however, the use of this approach can an impact on the hydrological cycle. We used simulations from Coupled Model Intercomparison Project (CMIP5) and Geoengineering Model Intercomparison Project (G3 simulation) to analyze the impacts of SAG on precipitation (P) and to determine its responsible causes in West Africa and Sahel region. CMIP5 historical data were first validated, the results obtained are consistent with observational data. Under the Representative Concentration Pathway scenario RCP4.5, a slight increase is found in the West Africa Region relative to present‐day climate. The dynamic processes especially, the monsoon shifts are responsible for this precipitation change. Under RCP4.5, during the monsoon period, reductions in P are 0.86%, 0.80% relative to the present‐day climate in the Northern and Southern Sahel, respectively, while precipitation is increased by 1.04% in the West African Region. Under SAG, we find a 3.71% decrease of precipitation in the West African Region while the precipitation decrease is 17.4% and 8.47% respectively in the North Sahel and South Sahel. This decrease in monsoon precipitation is mainly explained by changes in dynamics, which lead to weakened monsoon circulation and a shift in the distribution of monsoon precipitation. This result suggests that SAG deployment to balance all warming can be harmful to rainfall in WAR if the amount of SO2 to be injected into this tropical area is not taken into consideration

The western south atlantic ocean in a high-CO2 world: current measurement capabilities and perspectives

An international multi-disciplinary group of 24 researchers met to discuss ocean acidification (OA) during the Brazilian OA Network/Surface Ocean-Lower Atmosphere Study (BrOA/SOLAS) Workshop. Fifteen members of the BrOA Network (www. broa. furg. br) authored this review. The group concluded that identifying and evaluating the regional effects of OA is impossible without understanding the natural variability of seawater carbonate systems in marine ecosystems through a series of long-term observations. Here, we show that the western South Atlantic Ocean (WSAO) lacks appropriate observations for determining regional OA effects, including the effects of OA on key sensitive Brazilian ecosystems in this area. The impacts of OA likely affect marine life in coastal and oceanic ecosystems, with further social and economic consequences for Brazil and neighboring countries. Thus, we present (i) the diversity of coastal and open ocean ecosystems in the WSAO and emphasize their roles in the marine carbon cycle and biodiversity and their vulnerabilities to OA effects; (ii) ongoing observational, experimental, and modeling efforts that investigate OA in the WSAO; and (iii) highlights of the knowledge gaps, infrastructure deficiencies, and OA-related issues in the WSAO. Finally, this review outlines long-term actions that should be taken to manage marine ecosystems in this vast and unexplored ocean region

Surface Ocean CO2 Atlas (SOCAT) V3

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 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 living data publication documents changes in the methods and data sets used in this new version of the SOCAT data collection compared with previous publications of this data collection (Pfeil et al., 2013; Sabine et al., 2013; Bakker et al., 2014)