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Data refer to export fluxes of carbonate produced by calcifying phytoplankton (coccolithophores), and coccolith-CaCO₃ percent contribution to total carbonate flux across the tropical North Atlantic, from upwelling affected NW Africa, via three ocean sites along 12°N to the Caribbean. Sampling was undertaken by means of a spatial array of four time-series sediment traps (i.e., CB at 21°N 20°W; M1U at 12°N 23°W; M2U at 14°N 37°W; M4U at 12°N 49°W; Guerreiro et al., 2021) collecting particle fluxes in two-week intervals, from October 2012 to February 2014, allowing to track temporal changes along the southern margin of the North Atlantic central gyre. Auxiliary PIC (Particulate Inorganic Carbon) data from NASA's Ocean Biology Processing Group (https://oceancolor.gsfc.nasa.gov) are also provided for the sediment sampling period at all four trap sites. Particle flux data (mg/m²/d) of CaCO₃, organic matter, particulate organic carbon (POC), biogenic silica (bSiO₂) and unspecified residual fraction are provided for sediment trap site CB.

The Surface Ocean CO2 Atlas (SOCAT), an activity of the international marine carbon research community, provides access to synthesis and gridded fCO2 (fugacity of carbon dioxide) products for the surface oceans. Version 2 of SOCAT is an update of the previous release (version 1) with more data (increased from 6.3 million to 10.1 million surface water fCO2 values) and extended data coverage (from 1968-2007 to 1968-2011). The quality control criteria, while identical in both versions, have been applied more strictly in version 2 than in version 1. The SOCAT website (http://www.socat.info/) has links to quality control comments, metadata, individual data set files, and synthesis and gridded data products. Interactive online tools allow visitors to explore the richness of the data. Applications of SOCAT include process studies, quantification of the ocean carbon sink and its spatial, seasonal, year-to-year and longerterm variation, as well as initialisation or validation of ocean carbon models and coupled climate-carbon models.

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).

These datasets contain a six-year long record of shell morphology of the polar planktic foraminifera Neogloboquadrina pachyderma (sensu stricto) from near Palmer Station, Antarctica. The PARFLUX Mark 78H 21-sample trap was deployed in 170m water depth as part of the Palmer Long Term Ecological Research program (total water column depth 350 m, 64° 30'S, 66° 00'W). For manual analysis: Specimens were imaged using Olympus SZX7 transmitted light microscope, QImaging FAST 1394 camera and Q-Capture software. Image backgrounds were adjusted in Adobe PhotoshopCC 2015. Morphological parameters were measured using ImageProPlus 6.2. For automated analysis: Bulk samples measured using automated microscope and image analysis system that scans and captures images via a 12 MP Olympus CC12 camera attached to a Wild MZ3 incident light microscope (Analysis3.0)

Expansion of fresh and sea-ice loaded surface waters from the Arctic Ocean into the sub-polar North Atlantic is suggested to modulate the northward heat transport within the North Atlantic Current (NAC). The Reykjanes Ridge south of Iceland is a suitable area to reconstruct changes in the mid- to late Holocene fresh and sea-ice loaded surface water expansion, which is marked by the Subarctic Front (SAF). Here, shifts in the location of the SAF result from the interaction of freshwater expansion and inflow of warmer and saline (NAC) waters to the Ridge. Using planktic foraminiferal assemblage and concentration data from a marine sediment core on the eastern Reykjanes Ridge elucidates SAF location changes and thus, changes in the water-mass composition (upper ~200 m) during the last c. 5.8 ka BP. Our foraminifer data highlight a late Holocene shift (at c. 3.0 ka BP) in water-mass composition at the Reykjanes Ridge, which reflects the occurrence of cooler and fresher surface waters when compared to the mid-Holocene. We document two phases of SAF presence at the study site: from (i) c. 5.5 to 5.0 ka BP and (ii) c. 2.7 to 1.5 ka BP. Both phases are characterized by marked increases in the planktic foraminiferal concentration, which coincides with freshwater expansions and warm subsurface water conditions within the sub-polar North Atlantic. We link the SAF changes, from c. 2.7 to 1.5 ka BP, to a strengthening of the East Greenland Current and awarming in the NAC, as identified by various studies underlying these two currents. From c. 1.5 ka BP onwards, we record a prominent subsurface cooling and continued occurrence of fresh and sea-ice loaded surface waters at the study site. This implies that the SAF migrated to the southeast of our core site during the last millennium.

Future climate change as a result of increasing atmospheric CO2 concentrations is expected to strongly affect the oceans, with shallower winter mixing and consequent reduction in primary production and oceanic carbon drawdown in low and mid-latitudinal oceanic regions. Here we test this hypothesis by examining the effects of cold and warm winters on the carbonate system in the surface waters of the Northeast Atlantic Ocean for the period between 2005 and 2007. Monthly observations were made between the English Channel and the Bay of Biscay using a ship of opportunity program. During the colder winter of 2005/2006, the maximum depth of the mixed layer reached up to 650 m in the Bay of Biscay, whilst during the warmer (by 2.6 ± 0.5 °C) winter of 2006/2007 the mixed layer depth reached only 300 m. The inter-annual differences in late winter concentrations of nitrate (2.8 ± 1.1 μmol l−1) and dissolved inorganic carbon (22 ± 6 μmol kg−1, with higher concentrations at the end of the colder winter (2005/2006), led to differences in the dissolved oxygen anomaly and the chlorophyll α-fluorescence data for the subsequent growing season. In contrast to model predictions, the calculated air-sea CO2 fluxes (ranging from +3.7 to −4.8 mmol m−2 d−1) showed an increased oceanic CO2 uptake in the Bay of Biscay following the warmer winter of 2006/2007 associated with wind speed and sea surface temperature differences.

Over the last four decades of palaeoclimate research, significant emphasis has been placed on the Last Glacial Maximum (LGM) spanning 26.5-19 thousand years ago (ka), a period that saw significant (~125 m) sea-level reductions and major ice caps adorning large parts of the Northern Hemisphere. Here, we present evidence for another major glacial period spanning 71-59 ka (Marine Isotope Stage 4: MIS4) from a well-dated marine sequence offshore South Australia. The astronomically-tuned chronology of this deep-sea core is confirmed using single-grain optically stimulated luminescence dating (OSL), providing confidence in our high-resolution age model. Our approach to the study of our MD03-2607 core has been to employ many different proxies. These are: d18O of both planktic and benthic foraminifera for stratigraphic purposes, faunal counts of planktonic foraminifera to reconstruct the position of oceanic fronts and currents, alkenone palaeothermometry, XRF core scanning to determine the presence of aeolian dust, and eNd isotope to identify fluvial discharge over the core site. We compare our proxy findings with other archives for mainland Australia and Tasmania. Our multi-proxy palaeoclimate reconstructions are consistent with other marine, terrestrial and cryosphere archives across the Southern Hemisphere and suggest, for the first time, that MIS 4 was almost as dramatic as the LGM. During MIS4, global sea-level was reduced by ~100 m, glaciers across Australasia were more significant compared to the LGM, and sea-surface temperatures were much reduced. These glacial conditions uniformly peaked around 65ka. Global comparisons show major glacial conditions and vegetation shifts elsewhere during MIS4, but many are poorly dated. The significant environmental changes taking place during this glacial period were paralleled by waves of human dispersal across Eurasia and the earliest evidence of human occupation in northern Australia at 65ka.

The southern westerly wind belt (SWW) interacts with the Antarctic Circumpolar Current and strongly impacts the Southern Ocean carbon budget, and Antarctic ice-sheet dynamics across glacial- interglacial cycles. We investigated precipitation-driven sediment input changes to the Southeast Pacific off the southern margin of the Atacama Desert in Chile over the past one million years, revealing strong precession (19/23-ka) cycles. Our simulations with 2 ocean-atmosphere general circulation models suggest that observed cyclic rainfall changes are linked to meridional shifts in water vapor transport from the tropical Pacific toward the southern Atacama Desert. These changes reflect a precessional modulation of the split in the austral winter South Pacific jet stream. For precession maxima, we infer significantly enhanced rainfall in the southern Atacama Desert due to a stronger South Pacific split jet with enhanced subtropical/subpolar jets, and a weakermidlatitude jet. Conversely, we derive dry conditions in northern Chile related to reduced subtropical/subpolar jets and an enhanced midlatitude jet for precession minima. The presence of precessional cycles in the Pacific SWW, and lack thereof in other basins, indicate that orbital-scale changes of the SWW were not zonally homogeneous across the Southern Hemisphere, in contrast to the hemispherewide shifts of the SWW suggested for glacial terminations. The strengthening of the jet is unique to the South Pacific realm and might have affected winter-controlled changes in the mixed layer depth, the formation of intermediate water, and the built-up of sea-ice around Antarctica, with implications for the global overturning circulation and the oceanic storage of atmospheric CO2.

In this study we analyzed sediment trap time series from five tropical sites to assess seasonal variations in concentrations and fluxes of long-chain diols (LCDs) and associated proxies with emphasis on the long-chain diol index (LDI) temperature proxy. For the tropical Atlantic, we observe that generally less than 2 % of LCDs settling from the water column are preserved in the sediment. The Atlantic and Mozambique Channel traps reveal minimal seasonal variations in the LDI, similar to the two other lipid-based temperature proxies TEX86 and U37K′. In addition, annual mean LDI-derived temperatures are in good agreement with the annual mean satellite-derived sea surface temperatures (SSTs). In contrast, the LDI in the Cariaco Basin shows larger seasonal variation, as do the TEX86 and U37K′. Here, the LDI underestimates SST during the warmest months, which is possibly due to summer stratification and the habitat depth of the diol producers deepening to around 20–30 m. Surface sediment LDI temperatures in the Atlantic and Mozambique Channel compare well with the average LDI-derived temperatures from the overlying sediment traps, as well as with decadal annual mean SST. Lastly, we observed large seasonal variations in the diol index, as an indicator of upwelling conditions, at three sites: in the eastern Atlantic, potentially linked to Guinea Dome upwelling; in the Cariaco Basin, likely caused by seasonal upwelling; and in the Mozambique Channel, where diol index variations may be driven by upwelling from favorable winds and/or eddy migration.

Long chain n-alkanes are terrestrial higher plant biomarkers used to reconstruct continental paleoclimatic and paleohydrological conditions with marine sedimentary archives. Latitudinal variation in their concentration and distribution in marine sediments relatively close to the continent has been widely studied, but little is known on how far this continental signal extends into the ocean. Furthermore, no studies have examined the seasonal variation in the deposition of these biomarkers in marine sediments. Here we studied longitudinal variation in the composition of long chain n-alkanes and two other terrestrial higher plant biomarkers (long chain n-alkanols and long chain fatty acids) in atmospheric particles, as well as longitudinal and seasonal variation in long chain n-alkanes in sinking particles in the ocean at different water depths and in surface sediments, all collected along a 12°N transect across the tropical North Atlantic Ocean. The highest abundance of all three biomarker classes was closest to the African coast, as expected, because they are transported with Saharan dust and the largest part of the dust is deposited close to the source. At this proximal location, the seasonal variability in long chain n-alkane flux and the chain length distribution of the n-alkanes in sinking particles was most pronounced, due to seasonal change in the dust source or due to change in vegetation composition in the source area, related to the position of the Intertropical Convergence Zone (ITCZ). In contrast, in the open ocean the seasonal variability in both the long chain n-alkane flux and chain length distribution of the n-alkanes was low. The abundance of the alkanes was also lower, as expected because of the larger source-to-sink distance. At the western part of the transect, close to South America, we found an additional source of the alkanes in the sinking particles during spring and autumn in the year 2013. The d13C of the alkanes in the surface sediment closest to the South American continent indicated that the isotope signal is likely derived from C3 vegetation from the Amazon, implying an input from the Amazon River, as there is no significant aeolian input from South America there since the prevailing wind direction is from the east. Finally, the concentration of the alkanes was similar in the material collected from the atmosphere, the particles collected while settling through the marine water column, and in the surface sediments, providing evidence that degradation of long chain n-alkanes from the atmosphere to settling at the sediment-water interface at deep open ocean sites is minimal.