Productive parameters of seawater and epipelagic plankton and mesozooplankton biomass at stations of R/V Akademik Mstislav Keldysh during 1994-1998

Calculated and measured estimations of biomass of small (<3 mm), large (3-30 mm), and total zooplankton were verified (compared). These integral parameters of epipelagic communities were estimated by two methods. We used previously obtained regression equations, which correlate these parameters with water transparency. Measured values of aforesaid parameters were compared with their mean values in waters of different productivity estimated from NASA satellite maps. We compared data collected at fifteen stations in September-December in regions of different productivity in the North Atlantic. In warm regions (to the south of 40°N) measured and calculated values coincide well. In boreal regions in autumn bulk of mesozooplankton descends to deep layers due to seasonal migrations; hence correlation between measured and calculated values is disrupted. It is evident that correlation between water transparency and mesozooplankton biomass (integral index of water productivity) obtained before should be corrected for seasonal variations.

Abundance of ostracoda in sediment cores CRP-1 and CRP-2

Sparse, poorly preserved late Oligocene (3 species) and early Miocene (4 species) ostracod faunas have been recovered from CRP-2A, while relatively more abundant Quaternary faunas occur in CRP-1 (24 species). All taxa are marine. No definitive age assignments can be made on the two older faunas, which are not considered to be in situ, although the taxa identified are not at variance with sediment ages determined on other grounds. The Oligocene ostracods (Lithostratigraphical Unit, LSU 9.4) suggest deposition in cold, relatively shallow, shelf waters with faunal connections to the Antarctic Peninsula and South America, while the Miocene fauna (LSU 5.1) is considered to be a cool-cold, deeper water (?outer shelf) association with faunal connections to both New Zealand and the Antarctic Peninsula. The Quaternary faunas are primarily from LSU 3.1 (carbonate-rich layer), and suggest deposition in very cold, relatively quiet water that was at least 100 m, and possibly 130-200 m deep. None of the taxa are known from pre-Pleistocene sediments, and all occur in modern Antarctic/sub-Antarctic regimes, predominantly from south of 60° S. Specimens in the "carbonate-rich layer" probably have suffered minor penecontemporaneous fractionation, while the fauna in LSU 2.2 has suffered more extensive post-mortem transportation and possible reworking (though not necessarily from pre-Quaternary sources).

Radionuclides in sediment cores of the Atlantic sector of the Southern Ocean

We present time series of export productivity proxy data including 230Thex-normalized deposition rates (rain rates) of 10Be, dissolution-corrected biogenic Ba, and biogenic opal as well as authigenic U concentrations which are complemented by rain rates of total (detrital) Fe and sea ice indicating diatom abundances from five sediment cores across the Atlantic sector of the Southern Ocean covering the past 150,000 years. The results suggest that 10Be rain rates and authigenic U concentration cannot serve as quantitative paleoproductivity proxies because they have also been influenced by detrital particle fluxes in the case of 10Be and bulk sedimentation rates (sediment focussing) and deep water oxygenation in the case of U. The combined results of the remaining productivity proxies of this study (rain rates of biogenic opal and biogenic Ba in those sections without authigenic U) and other previously published proxy data from the Southern Ocean (231Pa/230Th and nitrogen isotopes) suggest that a combination of sea ice cover, shallow remineralization depth, and stratification of the glacial water column south of the present position of the Antarctic Polar Front and possibly Fe fertilization north of it have been the main controlling factors of export paleoproductivity in the Southern Ocean over the last 150,000 years. An overall glacial increase of export paleoproductivity is not supported by the data, implying that bioproductivity variations in the Southern Ocean are unlikely to have contributed to the major glacial atmospheric CO2 drawdown observed in ice cores.

(Table S1) Age determination of sediment core RAPiD-21-03K

A decadal resolution time series of sea surface temperature (SST) spanning the last two millennia is reconstructed by combining a proxy record from a new sediment sequence with previously published data from core MD99-2275, north of Iceland. The alkenone based SST reconstruction is validated with historic observational data and compared to a new similar temporal resolution reconstruction obtained from sediment core RAPiD21-3K, in the subpolar North Atlantic. The two SST paleorecords show consistent multidecadal scale coolings throughout the interval and similar expressions during the contrasted climatic periods 'colloquially known' as the Medieval Climatic Anomaly (MCA) and Little Ice Age (LIA). In order to further understand the temporal and spatial SST variations and investigate the influence of natural forcings on the observed SST changes during the last millennium, we compare our time series to simulations using the Institut Pierre-Simon Laplace IPSLCM4-v2 climate model. This comparison highlights the potential importance of volcanism as a natural forcing driving coherent abrupt cooling events captured in the subpolar North Atlantic records.

Sedimentology of the Rio Grande Rise area

Surface sediment samples and three gravity cores from the eastern terrace of the Vema Channel, the western flank of the Rio Grande Rise, and the Brazilian continental slope were investigated for physical properties, grain size, and clay mineral composition. Discharge of the Rio Doce is responsible for kaolinite enrichments on the slope south of 20° and at intermediate depths of the Rio Grande Rise. The long-distance advection of kaolinite with North Atlantic Deep Water from lower latitudes is of minor importance as evidenced by low kaolinite/chlorite ratios on the Mid-Atlantic Ridge. Cyclic variations of kaolinite/chlorite ratios in all our cores, with maxima in interglacials, are attributed to low-and high-latitude forcing of paleoclimate on the Brazilian mainland and the related discharge of the Rio Doce. A long-term trend toward more arid and 'glacial' conditions from 1500 ka to present is superimposed on the glacial-interglacial cyclicity.

Radionuclides in the water column at stations near the Antarctic Polar Front in the South Atlantic

Vertical profiles of dissolved and particulate 230Th and 231Pa were obtained across the Antarctic Circumpolar Current (ACC) in the southern Atlantic. North of the Polar Front, dissolved and total 230Th increase with depth in conformity with published scavenging models. There is no depletion of 230Th or 231Pa in the water column south of the Polar Front, thought to be an area of enhanced biological productivity. 230Th concentrations increase three-fold to the Weddell Sea across the ACC. Dissolved and total 231Pa concentrations are relatively constant below 500 m depth at about 0.3 dpm m**-3, and change little with depth or latitude. The results from the Weddell Gyre are explained by a mixing-scavenging model that takes into account the input of lower Circumpolar Deep Water through upwelling, which is the main source of water in the Weddell Gyre and is enriched in 230Th but not in 231Pa. 230Th accumulates in the Weddell Gyre as a result of a reduction in the scavenging rate and by ingrowth from 234U. Ingrowth is more significant for 230Th than for 231Pa because the residence time of water in the gyre (about 35 years) is similar to the scavenging residence time of Th in the south Atlantic (29 years) but shorter than that of Pa (120 years). It is argued that changes in 230Th accumulation in the past may reflect changes in water residence time and in the formation rate of Weddell Sea Deep Water.

Age model of sediment core V20-120 (Table 2)

Time series analyses of atmospheric and oceanic variables in a late Pleistocene record from the northwest Pacific show the complex relationship of the response of various segments of the climate system to changes in the earth's orbit. Most variance spectra of time series from this subarctic record contain frequency peaks with periods corresponding to at least one of the major orbital components of eccentricity, obliquity, or precession. Although the radiolarian faunal (water mass) assemblages have prominent spectral peaks with 41,000-year periods which are coherent with obliquity at this frequency, only the Transitional faunal assemblage contains variance focused at a frequency corresponding to the 100,000-year period of eccentricity. Three of these faunal time series also show variance concentrated at a frequency with a 20,000-year period. These three time series are not coherent at a 20,000-year frequency with either of the dominant spectral peaks of precession. They are coherent, however, with variations in the second harmonic of the obliquity cycle. Changes in obliquity apparently affect siliceous faunal abundances in the northwest Pacific region of this high-latitude site more than variations in eccentricity or precession. Maxima in the time series of quartz abundance occur during low values of eccentricity and high glacial ice volume. Because atmospheric winds serve as the major source of supply of quartz to the sediments at this site, these high quartz values reflect increased aridity at the source region. Except for short periods during interglacials, the characteristics of the surface waters in this region of the subarctic Pacific during much of the last 460,000 years were similar to those which exist today in the Sea of Okhotsk. The spectrum of winter sea surface temperature estimates, derived from siliceous microfaunal abundances, contains dominant frequency peaks at periods of 100,000, 41,000, and 23,000 years which are coherent with eccentricity, obliquity, and precession, respectively. Based upon the relationship of the Subarctic Front with the dominance of specific faunal asemblages, the front was positioned south of its present-day location throughout much of the late Pleistocene.

Data and Code archive for the interpolation of surface ocean carbon dioxide

We have developed a statistical gap-filling method adapted to the specific coverage and properties of observed fugacity of surface ocean CO2 (fCO2). We have used this method to interpolate the Surface Ocean CO2 Atlas (SOCAT) v2 database on a 2.5°×2.5° global grid (south of 70°N) for 1985-2011 at monthly resolution. The method combines a spatial interpolation based on a 'radius of influence' to determine nearby similar fCO2 values with temporal harmonic and cubic spline curve-fitting, and also fits long term trends and seasonal cycles. Interannual variability is established using deviations of observations from the fitted trends and seasonal cycles. An uncertainty is computed for all interpolated values based on the spatial and temporal range of the interpolation. Tests of the method using model data show that it performs as well as or better than previous regional interpolation methods, but in addition it provides a near-global and interannual coverage.

Composition of benthic taxa collected during POLARSTERN cruise ANT-XXI/5 (BENDEX) at Bouvet Island and Spiess Seamound

Bouvet (Bouvetøya) is a geologically young and very remote island just south of the Polar Front. Here we report samples taken during the RV "Polarstern" cruise ANTXXI/2 on 3 days in November 2003 and January 2004. This work was part of SCAR's EASIZ programme and intended, by providing data on the marine fauna of this "white gap" in the Atlantic sector of the Southern Ocean, to contribute to identifying the role of Bouvet in the faunal exchange between the Sub- and high Antarctic. While this goal demands extensive molecular analysis of the material sampled (future work), a checklist of the samples and data at hand widens the faunal and environmental inventory substantially. We suggest some preliminary conclusions on the relationship of Bouvet Island's fauna with that of other regions, such as Magellanic South America, the Antarctic Peninsula, and the high Antarctic Weddell Sea, which have been sampled previously. There seem to be different connections for individual higher taxa rather than a generally valid consistent picture.

Grain size analysis of ODP Site 162-984

Past changes in the freshwater balance of the surface North Atlantic Ocean are thought to have influenced the rate of deep-water formation, and consequently climate (Broecker and Denton, 1989, doi:10.1016/0016-7037(89)90123-3; Manabe and Stouffer, 1996; doi:10.1038/378165a0). Although water-mass proxies are generally consistent with an impact of freshwater input on meridional overturning circulation (Boyle and Keigwin, 1987, doi:10.1038/330035a0), there has been little dynamic evidence to support this linkage. Here we present a 25,000 year record of variations in sediment grain size from south of Iceland, which indicates vigorous bottom-water currents during both the last glacial maximum and the Holocene period. Together with reconstructions of North Atlantic water-mass distribution, vigorous bottom currents suggest a shorter residence time of northern-source waters during the last glacial maximum, relative to the Holocene period. The most significant reductions in flow strength occur during periods that have been associated with freshening of the surface North Atlantic. The short-term deglacial oscillations in bottom current strength are closely coupled to changes in Greenland air temperature, with a minimum during the Younger Dryas cold reversal and a maximum at the time of rapid warming at the onset of the Holocene. Our results support a strong connection between ocean circulation and rapid climate change.

Sr- and Nd-isotopic composition of bulk lithogenic sediments from the Eastern Mediterranean Sea (Table 1)

In order to characterize the provenance of lithogenic surface sediments from the Eastern Mediterranean Sea (EMS), residual (leached) fraction of 34 surface samples have been analysed for their 143Nd/144Nd and 87Sr/86Sr isotope ratios. The sample locations bracket all important entrances of riverine suspended matter into the EMS as well as all sub-basins of the EMS. The combined analyses of these two isotope ratios provide a precise characterization of the lithogenic fraction of surface sediments and record their dilution towards the central sub-basins. We reconstruct provenance and possible pathways of riverine dispersal and current redistribution, assuming more or less homogenous isotopic signatures and flux rates of the eolian fraction over the EMS. Lithogenic sediments entering the Ionian Sea from the Calabrian Arc and the Adriatic Sea are characterized by high 87Sr/86Sr isotope ratios and low epsilon-Nd(0) values (average 87Sr/86Sr=0.718005 and epsilon-Nd(0)=-11.06, n=5). Aegean Sea terrigenous sediments show an average ratio of 87Sr/86Sr=0.713089 (n=5) and values of epsilon-Nd(0)=-7.89 (n=5). The Aegean isotopic signature is traceable up to the southwest, south, and southeast of Crete. The sediment loads entering the EMS via the Aegean Sea are low and spread out mainly through the Strait of Casos (east of Crete). Surface sediments from the eastern Levantine Basin are marked by the highest epsilon-Nd(0) values (-3.3, n=6) and lowest 87Sr/86Sr isotope ratios (average 0.709541, n=6), reflecting the predominant input of the Nile sediment. The influence of the Nile sediment is traceable up to the NE-trending, eastern flank of the Mediterranean Ridge. The characterization of the modern riverine dispersal and eolian flux, based on isotope data, may serve as a tool to reconstruct climate-coupled variations of lithogenic sediment input into the EMS.