ALBERT

Description: Perturbations in stratospheric aerosol due to explosive volcanic eruptions are a primary contributor to natural climate variability. Observations of stratospheric aerosol are available for the past decades, and information from ice cores has been used to derive estimates of stratospheric sulfur injections and aerosol optical depth over the Holocene (approximately 10 000 BP to present) and into the last glacial period, extending back to 60 000 BP. Tephra records of past volcanism, compared to ice cores, are less complete but extend much further into the past. To support model studies of the potential impacts of explosive volcanism on climate variability across timescales, we present here an ensemble reconstruction of volcanic stratospheric sulfur injection (VSSI) over the last 140 000 years that is based primarily on terrestrial and marine tephra records. VSSI values are computed as a simple function of eruption magnitude based on VSSI estimates from ice cores and satellite observations for identified eruptions. To correct for the incompleteness of the tephra record, we include stochastically generated synthetic eruptions assuming a constant background eruption frequency from the ice core Holocene record. While the reconstruction often differs from ice core estimates for specific eruptions due to uncertainties in the data used and reconstruction method, it shows good agreement with an ice-core-based VSSI reconstruction in terms of millennial-scale cumulative VSSI variations over the Holocene. The PalVol reconstruction provides a new basis to test the contributions of forced vs. unforced natural variability to the spectrum of climate and the mechanisms leading to abrupt transitions in the palaeoclimate record with low- to high-complexity climate models. The PalVol volcanic forcing reconstruction is available at https://doi.org/10.26050/WDCC/PalVolv1 (Toohey and Schindlbeck-Belo, 2023).

Description: The Global Ocean Data Analysis Project (GLODAP) is a synthesis effort providing regular compilations of surface-to-bottom ocean biogeochemical bottle data, with an emphasis on seawater inorganic carbon chemistry and related variables determined through chemical analysis of seawater samples. GLODAPv2.2022 is an update of the previous version, GLODAPv2.2021 (Lauvset et al., 2021). The major changes are as follows: data from 96 new cruises were added, data coverage was extended until 2021, and for the first time we performed secondary quality control on all sulphur hexafluoride (SF6) data. In addition, a number of changes were made to data included in GLODAPv2.2021. These changes affect specifically the SF6 data, which are now subjected to secondary quality control, and carbon data measured onboard the RV Knorr in the Indian Ocean in 1994–1995 which are now adjusted using CRM measurements made at the time. GLODAPv2.2022 includes measurements from almost 1.4 million water samples from the global oceans collected on 1085 cruises. The data for the now 13 GLODAP core variables (salinity, oxygen, nitrate, silicate, phosphate, dissolved inorganic carbon, total alkalinity, pH, CFC-11, CFC-12, CFC-113, CCl4, and SF6) have undergone extensive quality control with a focus on systematic evaluation of bias. The data are available in two formats: (i) as submitted by the data originator but converted to World Ocean Circulation Experiment (WOCE) exchange format and (ii) as a merged data product with adjustments applied to minimize bias. For the present annual update, adjustments for the 96 new cruises were derived by comparing those data with the data from the 989 quality controlled cruises in the GLODAPv2.2021 data product using crossover analysis. SF6 data from all cruises were evaluated by comparison with CFC-12 data measured on the same cruises. For nutrients and ocean carbon dioxide (CO2) chemistry comparisons to estimates based on empirical algorithms provided additional context for adjustment decisions. The adjustments that we applied are intended to remove potential biases from errors related to measurement, calibration, and data handling practices without removing known or likely time trends or variations in the variables evaluated. The compiled and adjusted data product is believed to be consistent to better than 0.005 in salinity, 1 % in oxygen, 2 % in nitrate, 2 % in silicate, 2 % in phosphate, 4 μmol kg-1 in dissolved inorganic carbon, 4 μmol kg-1 in total alkalinity, 0.01–0.02 in pH (depending on region), and 5 % in the halogenated transient tracers. The other variables included in the compilation, such as isotopic tracers and discrete CO2 fugacity (fCO2), were not subjected to bias comparison or adjustments.

Description: Heinrich events are among the dominant modes of glacial climate variability. During these events, massive iceberg armadas were released by the Laurentide Ice Sheet, sailed across the Atlantic, and caused large-scale climate changes. We study these events in a fully coupled complex ice sheet–climate model with synchronous coupling between ice sheets and oceans. The ice discharges occur as internal variability of the model with a recurrence period of 5kyr, an event duration of 1–1.5kyr, and a peak discharge rate of about 50mSv, roughly consistent with reconstructions. The climate response shows a two-stage behavior, with freshwater release effects dominating the surge phase and ice-sheet elevation effects dominating in the post-surge phase. As a direct response to the freshwater discharge during the surge phase, the deepwater formation in the North Atlantic decreases and the North Atlantic deepwater cell weakens by 3.5Sv. With the reduced oceanic heat transport, the surface temperatures across the North Atlantic decrease, and the associated reduction in evaporation causes a drying in Europe. The ice discharge lowers the surface elevation in the Hudson Bay area and thus leads to increased precipitation and accelerated ice sheet regrowth in the post-surge phase. Furthermore, the jet stream widens to the north and becomes more zonal. This contributes to a weakening of the subpolar gyre, and a continued cooling over Europe even after the ice discharge. This two-stage behavior can explain previously contradicting model results and understandings of Heinrich Events.

Description: In this study, we propose a statistical method to validate sea-level reconstructions using geological records known as sea-level indicators (SLIs). SLIs are often the only available data to retrace late-glacial relative sea level (RSL). Determining the RSL from SLI height is not straight forward, the elevation at which an SLI was found usually does not represent the past RSL. In contrast, it has to be related to past RSL by investigating sample’s type, habitat and deposition conditions. For instance, water distribution at which a specific specimen is found today can be related to the indicator's depositional height range. Furthermore, the precision of dating varies between geological samples, and, in case of radiocarbon dating, the age has to be calibrated using a non-linear calibration curve. To avoid an a-priori assumption like normal-distributed uncertainties, we define likelihood functions which take into account the indicative meaning’s available error information and calibration statistics represented by joint probabilities. For this conceptional study, we restrict ourselves to one type of indicators, shallow-water shells, which are usually considered as low-grade samples giving only a lower limit of former sea level, as the depth range in which they live spreads over several tens of meters, and does not follow a normal distribution. The presented method is aimed to serve as a strategy for glacial isostatic adjustment reconstructions, in this case for the German Paleo-Climate Modelling Initiative PalMod (https://www.palmod.de/en) and by extending it to other SLI types.

Description: Dynamic vegetation models simulate global vegetation in terms of fractional coverages of a few plant functional types (PFTs). Although these models often share the same concept, they differ with respect to the number and kind of PFTs, complicating the comparability of simulated vegetation distributions. Pollen-based reconstructions are initially only available in form of time-series of individual taxa that are not distinguished in the models. Thus, to evaluate simulated vegetation distributions, the modelling results and pollen-based reconstructions have to be converted into a comparable format. The classical approach is the method of biomisation, but hitherto, PFT-based biomisation methods were only available for individual models. We introduce and evaluate a simple, universally applicable technique to harmonize PFT-distributions by assigning them into nine mega-biomes that follow the definitions commonly used for vegetation reconstructions. The method works well for all state-of the art dynamic vegetation models, independent of the spatial resolution or the complexity of the models. Large biome belts (such as tropical forest) are well represented, but regionally confined biomes (warm-mixed forest, Savanna) are only partly captured. Overall, the PFT-based biomisation is able to keep up with the conventional biomisation approach of forcing biome models (here: BIOME1) with the background climate states. The new method has, however, the advantage that it allows a more direct comparison and evaluation of the vegetation distributions simulated by Earth System Models. Thereby, the new method provides a powerful tool for the evaluation of Earth System Models in general.

Description: We have developed a new module to calculate soil organic carbon (SOC) accumulation in perennially frozen ground in the land surface model JSBACH. Running this offline version of MPI-ESM we have modelled permafrost carbon accumulation and release from the Last Glacial Maximum (LGM) to the Pre-industrial (PI). Our simulated near-surface PI permafrost extent of 16.9Miokm2 is close to observational evidence. Glacial boundary conditions, especially ice sheet coverage, result in profoundly different spatial patterns of glacial permafrost extent. Deglacial warming leads to large-scale changes in soil temperatures, manifested in permafrost disappearance in southerly regions, and permafrost aggregation in formerly glaciated grid cells. In contrast to the large spatial shift in simulated permafrost occurrence, we infer an only moderate increase of total LGM permafrost area (18.3Miokm2) – together with pronounced changes in the depth of seasonal thaw. Reconstructions suggest a larger spread of glacial permafrost towards more southerly regions, but with a highly uncertain extent of non-continuous permafrost. Compared to a control simulation without describing the transport of SOC into perennially frozen ground, the implementation of our newly developed module for simulating permafrost SOC accumulation leads to a doubling of simulated LGM permafrost SOC storage (amounting to a total of ~150PgC). Despite LGM temperatures favouring a larger permafrost extent, simulated cold glacial temperatures – together with low precipitation and low CO2 levels – limit vegetation productivity and therefore prevent a larger glacial SOC build-up in our model. Changes in physical and biogeochemical boundary conditions during deglacial warming lead to an increase in mineral SOC storage towards the Holocene (168PgC at PI), which is below observational estimates (575PgC in continuous and discontinuous permafrost). Additional model experiments clarified the sensitivity of simulated SOC storage to model parameters, affecting long-term soil carbon respiration rates and simulated active layer depths. Rather than a steady increase in carbon release from the LGM to PI as a consequence of deglacial permafrost degradation, our results suggest alternating phases of soil carbon accumulation and loss as an effect of dynamic changes in permafrost extent, active layer depths, soil litter input, and heterotrophic respiration.

Description: Climate reconstructions based on proxy records recovered from marine sediments, such as alkenone records or geochemical parameters measured on foraminifera, play an important role in our understanding of the climate system. They provide information about the state of the ocean ranging back hundreds to millions of years and form the backbone of paleo-oceanography. However, there are many sources of uncertainty associated with the signal recovered from sediment archived proxies. These include seasonal or depth habitat biases in the recorded signal, a frequency dependent reduction in the amplitude of the recorded signal due to bioturbation of the sediment, aliasing of high frequency climate variation onto a nominally annual, decadal or centennial resolution signal, and additional sample processing and measurement error introduced when the proxy signal is recovered. Here we present a forward model for sediment archived proxies that jointly models the above processes, so that the magnitude of their separate and combined effects can be investigated. Applications include the interpretation and analysis of uncertainty in existing proxy records, parameter sensitivity analysis to optimize future studies, and the generation of pseudo-proxy records that can be used to test reconstruction methods. We provide examples, such as the simulation of individual foraminifera records, that demonstrate the usefulness of the forward model for paleoclimate studies. The model is implemented as a user-friendly R package, sedproxy, the use of which we hope will contribute to a better understanding of both the limitations and potential of marine sediment proxies to inform about past climate.

Description: The Argentine margin contains important sedimentological, paleontological and chemical records of regional and local tectonic evolution, sea level, climate evolution and ocean circulation since the opening of the South Atlantic in the Late Jurassic–Early Cretaceous as well as the present-day results of post-depositional chemical and biological alteration. Despite its important location, which underlies the exchange of southern- and northern-sourced water masses, the Argentine margin has not been investigated in detail using scientific drilling techniques, perhaps because the margin has the reputation of being erosional. However, a number of papers published since 2009 have reported new high-resolution and/or multichannel seismic surveys, often combined with multi-beam bathymetric data, which show the common occurrence of layered sediments and prominent sediment drifts on the Argentine and adjacent Uruguayan margins. There has also been significant progress in studying the climatic records in surficial and near-surface sediments recovered in sediment cores from the Argentine margin. Encouraged by these recent results, our 3.5-day IODP (International Ocean Discovery Program) workshop in Buenos Aires (8–11 September 2015) focused on opportunities for scientific drilling on the Atlantic margin of Argentina, which lies beneath a key portion of the global ocean conveyor belt of thermohaline circulation. Significant opportunities exist to study the tectonic evolution, paleoceanography and stratigraphy, sedimentology, and biosphere and geochemistry of this margin.

Description: The current generation of marine biogeochemical modules in Earth system models (ESMs) considers mainly the effect of marine biota on the carbon cycle. We propose to also implement other biologically driven mechanisms in ESMs so that more climate-relevant feedbacks are captured. We classify these mechanisms in three categories according to their functional role in the Earth system: (1) "biogeochemical pumps", which affect the carbon cycling; (2) "biological gas and particle shuttles", which affect the atmospheric composition; and (3) "biogeophysical mechanisms", which affect the thermal, optical, and mechanical properties of the ocean. To resolve mechanisms from all three classes, we find it sufficient to include five functional groups: bulk phyto- and zooplankton, calcifiers, and coastal gas and surface mat producers. We strongly suggest to account for a larger mechanism diversity in ESMs in the future to improve the quality of climate projections.

Description: Earthquake history shows that the Sunda subduction zone of the Indonesian margin produces great earthquakes offshore Sumatra, whereas earthquakes of comparable magnitude are lacking offshore Java and the Lesser Sunda islands. Morphological structures from multibeam bathymetric data across the forearc relate with the extent of the seismogenic zone (SZ). Off Java and the Lesser Sunda islands the Indo-Australian plate subducts almost normal underneath the oceanic plate of the Indonesian archipelago. Landward of the trench, the outer wedge of the slope break is ~50 km uniformly wide with uniform bathymetric gradients. The slope of the outer wedge is locally cut by one/two steeper ridges of ~5 km extent. The sharp slope break corresponds to the updip limit of the SZ, which is also associated with the seawardmost part of the outer arc high. Landward of the slope break we find narrow, uniform outer arc ridges. The landward termination of these ridges coincides with the downdip limit of the SZ. The intersection of the shallow upper plate mantle with the subduction thrust fault marks the downdip limit of the SZ beneath the forearc. Off Sumatra the Indo-Australian plate subducts obliquely underneath the continental part of the Indonesian Sunda margin. Landward of the trench, the outer wedge varies, being mostly ~70 km wide, in some areas narrowing to 50 km width. The lower slope bathymetric gradients are steep. The outer wedge slope is made up of several steeper ridges of ~5 km extent. The slope break is only locally sharp, and corresponds to the updip limit of the SZ. The outer arc ridges off Sumatra are, in comparison with the forearc structures off Java and the Lesser Sunda islands, wider and partly elevated above sea level forming the Mentawai forearc islands. The downdip limit of the SZ coincides with the intersection of a deeper upper plate mantle with the subduction thrust fault beneath the forearc. Sunda Strait marks a transition zone between the Sumatra and Java margins. Seafloor morphology enables the identification of the seismogenic zone (SZ) across the entire Sunda margin. The SZ is uniformly wide for the Sumatra margin and narrows off Sunda Strait. Sunda Strait is the transition between the Sumatra margin and the uniformly narrow extent of the SZ of the Java/Lesser Sunda margin. Comparing the Java and Lesser Sunda islands with the Sumatra margin we find the differences along the Sunda margin, especially the wider extent of the SZ off Sumatra, producing larger earthquakes, to result from the combination of various causes: The sediment income on the oceanic incoming plate and the subduction direction; we attribute a major role to the continental/oceanic upper plate nature of Sumatra/Java influencing the composition and deformation style along the forearc and subduction fault. Off Sumatra the SZ is up to more than twice as wide as off Java/Lesser Sunda islands, enlarging the unstable regime off Sumatra and thus the risk of sudden stress release in a great earthquake.

Description: EGU2011-407 The spatial and temporal distribution of sea ice in the subpolar North Atlantic is mainly controlled by the advection of warm Atlantic Water via the Norwegian and West Spitsbergen Current in eastern Fram Strait. Simultaneously, polar water and sea ice from the Arctic Ocean is transported southward by the East Greenland Current. Hence, variations in the strength of this oceanic circulation regime may either stimulate or reduce the sea ice extent. Based on organic geochemical studies of a high-resolution sediment core from eastern Fram Strait we provide new evidence for the highly variable character of the sea ice conditions in this area. The combination of the sea ice proxy IP25 (Belt et al., 2007) with phytoplankton derived biomarkers (e.g. brassicasterol, dinosterol; Volkman 2006) enables a reliable reconstruction of sea surface and sea ice conditions, respectively (Müller et al., 2009; 2010). By means of these biomarkers, we trace gradually increasing sea ice occurrences from the Mid to the Late Holocene – consistent with the neoglacial cooling trend. Throughout the past ca. 3,000 years (BP) we observe a significant short-term variability in the biomarker records, which points to rapid advances and retreats of the sea ice cover at the continental margin of West Spitsbergen. The co-occurrence of IP25 and phytoplankton markers, however, suggests that the primary productivity benefits from these sea ice surges. As such, higher amounts of open-water phytoplankton biomarkers together with peak abundances of IP25 indicate recurring periods of enhanced ice-edge phytoplankton blooms at the core site. To what extent a seesawing of temperate Atlantic Water may account for these sea ice fluctuations requires further investigation. Concurrent variations in Siberian river discharge (Stein et al., 2004) or Norwegian glacier extents (Nesje et al., 2001), however, strengthen that these fluctuations may be assigned to variations in the North Atlantic/Arctic Oscillation (NAO/AO) and (hence) a weakened/accelerated Atlantic Water input and Arctic sea ice export.

Description: The upwelling area in the eastern equatorial Pacific off Peru is one of the most pronounced oxygen minimum zones (OMZs) of the modern ocean. Modeling scenarios predict an expansion of the OMZs in the course of global change in the coming decades. As a consequence, the Peruvian continental margin represents a key locality for studies on biogeochemical dynamics in the future ocean. We present pore water and sediment data for redox-sensitive metals (Fe, Mn, V, Mo, and U) that have been collected along a transect across the Peruvian margin at 11°S. The results are used to evaluate the behavior of trace metals in a wide range of biogeochemical and hydrodynamic settings. In the core of the OMZ, where permanently anoxic conditions prevail, redox sensitive metals exhibit diagenetic behaviors largely consistent with previous studies. Vanadium and Mo are released from Fe oxihydroxides and subsequently recycled through diffusion across the benthic boundary or trapped through formation of authigenic V phases and sequestration of Mo by authigenic pyrite. Some U is delivered through diffusion across the benthic boundary, reduction and precipitation of UO2 and incorporation into phosphorites. The utmost part of the buried U, however, is delivered in particulate form, most likely as bioauthigenic U which cannot be recycled in the suboxic waters overlying the anoxic sediments. In contrast to sediments in the core of the OMZ, sediments on the shelf experience frequent oxygenation episodes related to the passage of internal waves and the regular recurrence of El Niño events. These oxygenation episodes lead to the re-oxidation and remobilization of authigenic U and V. In contrast to that, the authigenic accumulation of Mo is favored by the occasional occurrence of slightly oxidizing conditions. This is most likely due to enhanced formation of sulfur intermediates necessary for pyrite formation and the increased stability of pyrite, the major Mo sink, under oxidizing conditions, compared to authigenic V and U phases. Redox oscillations in the Peruvian OMZ thus lead to a discrimination of U against Mo, a mechanism that should be considered in the interpretation of U/Mo systematics in paleo redox studies. Overall our results provide valuable constraints on how trace metal inventories of marginal sediments may respond to expanding shelf anoxia and to short term perturbations of sediment redox conditions.

Description: EGU2011-12780 A temporary passive seismic network of 31 broad-band stations was deployed in the region around Talca and Constitución between 35°S to 36°S latitude and 71°W to 72.5°W longitude. The network was operated between March and October 2008. Thus, we recorded data prior the magnitude Mw=8.8 earthquake of 27 February 2010 at a latitude of the major slip and surface uplift. The experiment was conducted to address fundamental questions on deformation processes, crustal and mantle structures, and fluid flow. We present results of a teleseismic P receiver function study that covers the coastal region and reaches to the Andes. The aim is to determine the structure and thickness of the continental crust and constrain the state of hydration of the mantle wedge. The P-wave receiver function technique requires large teleseismic earthquakes from different distances and backazimuths. A few percent of the incident P-wave energy from a teleseismic event will be converted into S-wave (Ps) at significant and relatively sharp discontinuities beneath the station. A small converted S phase is produced that arrives at the station within the P wave coda directly after the direct P-wave. The converted Ps phase and their crustal multiples contain information about crustal properties, such as Moho depth and the crustal vp/vs ratio. We use teleseismic events with magnitudes mb 〉 5.5 at epicentral distances between 30° and 95° to examine P-to-S converted seismic phases. Our preliminary results provide new information about the thickness of the continental crust beneath the coastal region in Central Chile. At most of the stations we observed significant energy from P to S converted waves between 4 and 5 s after the direct P-wave within a positive phase interpreted as the Moho, occurring at 35 to 40 km. The great Maule earthquake of 27 February 2010 nucleated up-dip of the continental Moho. The rupture of this earthquake seems to have propagated down-dip of the Moho. The Moho reflection show a positive polarity, indicating that the mantle is either dry or only moderately hydrated. We observed converted energy from an intracrustal boundary at around 2 s that disappears near the coast. Further, positive polarity peaks occur that are possibly caused by the down going plate.

Description: EGU2011-8738 At present, the Arctic is responding faster to global warming than most other areas on earth, as indicated by rising air temperatures, melting glaciers and ice sheets and a decline of the sea ice cover. As part of the meridional overturning circulation which connects all ocean basins and influences global climate, northward flowing Atlantic Water is the major means of heat and salt advection towards the Arctic where it strongly affects the sea ice distribution. Records of its natural variability are critical for the understanding of feedback mechanisms and the future of the Arctic climate system, but continuous historical records reach back only ca. 150 years. To reconstruct the history of temperature variations in the Fram Strait Branch of the Atlantic Current we analyzed a marine sediment core from the western Svalbard margin. In multidecadal resolution the Atlantic Water temperature record derived from planktic foraminifer associations and Mg/Ca measurements shows variations corresponding to the well-known climatic periods of the last millennium (Medieval Climate Anomaly, Little Ice Age, Modern/Industrial Period). We find that prior to the beginning of atmospheric CO2 rise at ca. 1850 A.D. average summer temperatures in the uppermost Atlantic Water entering the Arctic Ocean were in the range of 3-4.5°C. Within the 20th century, however, temperatures rose by ca. 2°C and eventually reached the modern level of ca. 6°C. Such values are unprecedented in the 1000 years before and are presumably linked to the Arctic Amplification of global warming. Taking into account the ongoing rise of global temperatures, further warming of inflowing Atlantic Water is expected to have a profound influence on sea ice and air temperatures in the Arctic.

Description: EGU2011-1847-3 Lake Van is a lake by volume of 607 km3 and a maximum depth of 450 meters in a tectonically active zone in eastern Anatolia, Turkey. In summer 2010, Lake Van was the target of a deep drilling campaign (PaleoVan) in the frame of ICDP (International Continental Scientific Drilling Program). Two sites were drilled based on reflection seismic data collected during a seismic campaign in 2004. Here we present a first joint interpretation of the seismic and drilling data. Interpretation of seismic reflection data from lake reveals three physiographic provinces: a lacustrine shelf, a lacustrine slope, and a deep, relatively flat lake basin. The most prominent features of the lacustrine shelf and slope are prograding deltaic sequences, numerous unconformities, submerged channels, as well as closely spaced U- and/or V-shaped depressions, reflecting the variable lake level history of Lake Van. The seismic units of the shelf are dominantly composed of low-to-good continuity, variable amplitude reflections interpreted as fluvial deposits. The lake consists of three prominent basins (Tatvan, Deveboynu, and Northern Basins), separated by basement highs or ridges (Ahlat Ridge). The seismic units corresponding to these basins mainly consist of low to very high amplitude, well-stratified reflection patterns. Chaotic reflections are seen in parts of these basins. The Deveboynu Basin consists mainly of chaotic reflections. The Tatvan and Northern Basins are characterized by an alternating succession of well-stratified and chaotic reflecting layers. The chaotic seismic facies are interpreted as slump and slide deposits, which are probably the result of quick lake level fluctuations and/or earthquakes. The moderateto high amplitude, well-stratified facies seen in the deep parts of the basins away from the terrigenous sediment sources are interpreted as lacustrine deposits and tephra layers. The total sediment thickness in the deep parts of the lake is over 400 m. Prominent clinoforms indicate the initial flooding of Lake Van about 500 ka ago. The acoustic basement and the sediments lying on top of the basement in the southern part of the lake are disrupted by various intrusions and extrusions suggesting active volcanism. Synthetic seismograms calculated based on core logging, wire-line logging and check shot data will allow the correlation between seismic and drill data. This approach will allow extrapolating the stratigraphy from the wells to 3D-space by using the seismic data.

Description: EGU2011-4235 The Arctic is undergoing rapid environmental and economic transformations. Recent climate warming, which is simplifying access to oil and gas resources, enabling trans Arctic shipping, and shifting the distribution of harvestable resources, has brought the Arctic Ocean to the top of national and international political agendas. Scientific knowledge of the present status of the Arctic Ocean and the process-based understanding of the mechanics of change are urgently needed to make useful predictions of future conditions throughout the Arctic region. These are required to plan for the consequences of climate change. A step towards improving our capacity to predict future Arctic change was undertaken with the Second International Conference on Arctic Research Planning (ICARP II) meetings in 2005 and 2006, which brought together scientists, policymakers, research managers, Arctic residents, and other stakeholders interested in the future of the Arctic region. The Arctic in Rapid Transition (ART) Initiative developed out of the synthesis of the several resulting ICARP II science plans specific to the marine environment. This process started in October 2008 and has been driven by early career scientists. The ART Initiative is an integrative, international, multi-disciplinary, long-term pan-Arctic network to study changes and feedbacks with respect to physical characteristics and biogeochemical cycles in the Arctic Ocean in a state of rapid transition and its impact on the biological production. The first ART workshop was held in Fairbanks, Alaska, in November 2009 with 58 participants from 9 countries. Workshop discussions and reports were used to develop a science plan that integrates, updates, and develops priorities for Arctic Marine Science over the next decade. The science plan was accepted and approved by the International Arctic Science Committee (IASC) Marine Group, the former Arctic Ocean Science Board. The second ART workshop was held in Winnipeg, Canada, in October 2010 with 20 participants from 7 countries to develop the implementation plan. Our focus within the ART Initiative will be to bridge gaps in knowledge not only across disciplinary boundaries (e.g., biology, geochemistry, geology, meteorology, physical oceanography), but also across geographic (e.g., international boundaries, shelves, margins, and the central Arctic Ocean) and temporal boundaries (e.g., alaeo/geologic records, current process observations, and future modeling studies). This approach of the ART Initiative will provide a means to better understand and predict change, particularly the consequences for biological productivity, and ultimate responses in the Arctic Ocean system. More information about the ART Initiative can be found at http://aosb.arcticportal.org/art.html.

Description: EGU2011-13199 Images of crustal construction provide a key to understand the interplay of magmatism and tectonism while oceanic crust is build up. Bathymetric data show that the crustal construction is highly variable. Areas that are dominated by magmatic processes are adjacent to areas that are highly tectonised and where mantle rocks were found. The Mid-Atlantic Ridge at 22°N shows this high variability along the ridge axis, within the TAMMAR segment, and from segment to segment. However, this strong variability occurs also off-axis, spreading parallel, representing different times in the same area of the ridge. A fracture zone, with limited magma supply, has been replaced by a segment centre with a high magmatic budget. Roughly 4.5 million years ago, the growing magmatic active TAMMAR segment, propagated into the fracture zone, started the migration of the ridge offset to the south, and stopped the formation of core complexes. We present data from seismic refraction and wide-angle reflection profiles that surveyed the crustal structure across the ridge crest of the TAMMAR segment. These yield the crustal structure at the segment centre as a function of melt supply. The results suggest that crust is ~8 km thick near the ridge and decreases in thickness with offset to the ridge axis. Seismic layer 3 shows profound changes in thickness and becomes rapidly one kilometre thicker approx. 5 million years ago. This correlates with gravimetric data and the observed “Bull’s eye” anomaly in that region. Our observations support a temporal change from thick lithosphere with oceanic core complex formation to thin lithosphere with focussed mantle upwelling and segment growing. The formation of ‘thick-crust’ volcanic centre seems to have coincided with the onset of propagation 4.5 million years ago.

Description: EGU2011-6081 Natural stable isotopes are a powerful tool in marine sciences to investigate biological processes, such as present and past nutrient utilization. In this study we present the first dissolved silicon isotope data in the upwelling area off Peru, where one of the world’s largest Oxygen Minimum Zones (OMZ) is located. Silicon is the most important component required for phytoplankton (diatom) growth, which dominates primary productivity in this region. Stable Si isotopes are fractionated during diatom growth in that the lighter Si isotopes are preferentially incorporated into diatoms with a fractionation factor of -1.1 promille. The Si isotope composition of dissolved silicic acid of the corresponding surface waters is therefore left isotopically heavier. The Si isotope composition, 30Si/28Si, is expressed as δ30Si values, which stand forh deviations from a given standard (NBS28). Investigation of the dissolved seawater Si isotope composition thus provides a measure for the utilization and, combined with information on the Si isotope composition of the water masses upwelling off Peru, it is a measure for the supply pathways of Si to the coastal upwelling centres. Surface waters on the shelf off Peru are mainly fed by the Equatorial Undercurrent, which mainly consists of waters originating from the western and Central Pacific and which has a characteristic δ30Si of +1.5 promille. In areas and during phases of intense upwelling the fractionation of Si isotopes was observed to be weaker due to upwelling-driven supply of less fractionated Si (δ30Si = 1.7 promille, from water depths of around 100-150 m, whereas under weak upwelling conditions fractionation is higher (δ30Si ~3 promille due to a more complete utilization of the available dissolved silicate. The distribution of dissolved δ30Si correlates strongly with particulate biogenic silicate (opal) concentrations in that highest opal concentrations in the surface waters show the lowest δ30Si values thus strongest upwelling intensity. The most extreme δ30Si values in surface waters (δ30Si = 4.5 promille are observed offshore where silicic acid concentrations are nearly zero. Furthermore we compare the δ30Si data with the dissolved nitrogen isotope distribution, which in addition to nitrate utilization is mainly influenced by denitrification and annamox processes in the OMZ. Combined silicon and nitrogen isotope compositions can thus help to disentangle different fractionation processes within the nitrogen cycle.

Description: EGU2011-2455 The current interglacial has gone through a variety of warmer and colder periods. Consistent with the decreasing solar insolation during the Holocene, warmest conditions have occurred particularly within its earliest phase. We studied high-resolution sediment sequences from the Western Svalbard margin covering the last ca 10,000 years in order to reconstruct the variations of Atlantic Water advection to the Arctic, the sea ice extent, and the structure of the water column on the Westspitsbergen continental margin. The Fram Strait, often referred to as the Arctic Gateway, is the only deep-water passage for Atlantic-derived water masses to enter the Arctic Ocean. Northward advection of relatively warm and saline Atlantic Water masses keeps the eastern part of the Fram Strait ice-free all year. It therefore plays a crucial role for the heat budget of the Arctic. A multiproxy data set including geochemical, micropaleontological, and sedimentological parameters was established with centennial to multidecadal time resolution. Records of foraminiferal oxygen and carbon isotopes, planktic foraminifer assemblages, and the amount of ice rafted debris clearly reveal distinct variations between climatically warmer and colder intervals throughout this period. Planktic foraminifer assemblages reveal warmest conditions for the early Holocene period (ca 10-8 ka). A second warming pulse is detected between 5 and 6 ka. In the second half of the Holocene, increased IRD contents are indicative of a significant cooling trend. Despite of the decreasing solar insolation planktic foraminiferal assemblages suggest a return of slightly strengthened Atlantic Water advection around 3 to 2 ka and a strong warming event in the present, anthropogenically influenced period.

Description: We determined the isotopic composition of neodymium (Nd) and lead (Pb) of past seawater to reconstruct water mass exchange and erosional input between the Arctic Ocean and the Norwegian-Greenland Seas over the past 5 Ma. For this purpose, sediments of ODP site 911 (leg 151) located at 900 m water depth on the Yermak Plateau in the Fram Strait were used. The paleo-seawater variability of Nd and Pb isotopes was extracted from the sea water-derived metal oxide coatings on the sediment particles following the leaching method of Gutjahr et al. (2007). All radiogenic isotope data were acquired by Multi-Collector (MC) ICP-MS. The site 911 stratigraphy of Knies et al. (2009) was applied. Surface sediment Sr and Nd isotope data, as well as downcore Sr isotope data obtained on the same leaches are close to seawater and confirm the seawater origin of the Nd and Pb isotope signatures. The deep water Nd isotope time series extracted from site 911 was in general more radiogenic ("Nd = -7.5 to -10) than present day deep water ("Nd = -9.8 to -11.8) in the area of the Fram Strait (Andersson et al., 2008) and does not show a systematic trend with time. In contrast, the radiogenic isotope composition of Pb evolved from 206Pb/204Pb ratios around 18.7 to more radiogenic values around 19.2 between 2 Ma and today. The data indicate that mixing of water masses from the Arctic Ocean and the Norwegian-Greenland Seas has controlled the Nd isotope signatures of deep waters on the Yermak Plateau over the past 5 Ma. Prior to 1.7 Ma the Nd isotope signatures on the Yermak Plateau were less radiogenic than waters from the same depth in the central Arctic Ocean (Haley et al., 2008) pointing to a greater influence from the Norwegian-Greenland Seas. After 1.7 Ma the central Arctic and Yermak Plateau data have varied around similar values indicating water mass mixing overall similar to today. In contrast, the Pb isotope composition of deep waters in the Fram Strait appears to have been dominated by weathering inputs from glacially weathering old continental landmasses, such as Greenland or parts of Svalbard since 2 Ma. A similar control over the Pb isotope evolution of seawater since the onset of Northern Hemisphere Glaciation was recorded by ferromanganese crusts that grew from North Atlantic DeepWater in the western North Atlantic. References: Gutjahr, M., Frank, M., Stirling, C.H., Klemm, V., van de Flierdt, T. and Halliday, A.N. (2007): Reliable extraction of a deepwater trace metal isotope signal from Fe-Mn oxyhydroxide coatings of marine sediments.- Chemical Geology 242, 351-370 Haley B. A., M. Frank, R.F. Spielhagen and A. Eisenhauer (2008): Influence of brine formation on Arctic Ocean circulation over the past 15 million years. Nature Geoscience 1, 68–72 Andersson, P.S., Porcelli, D., Frank, M., Björk, G., Dahlqvist, R. and Gustafsson, Ö. (2008): Neodymium isotopes in seawater from the Barents Sea and Fram Strait Arctic- Atlantic gateways.- Geochim. Cosmochim. Acta 72, 2854-2867 Knies, J., J. Matthiessen, C. Vogt, J.S. Laberg, B.O. Hjelstuen, M.Smelror, E. Larsen, K. Andreassen, T. Eidvin and T.O. Vorren (2009): The Plio-Pleistocene glaciation of the Barents Sea–Svalbard region: a new model based on revised chronostratigraphy - Quaternary Science Reviews 28, 9-10, 812-829

Description: EGU2011-12864 The Woodlark Basin east of Papua New Guinea represents one of the few places on Earth where a spreading axis propagates into continental crust. This special tectonic setting allows insights into the evolution of magma composition as continental extension and break-up changes to the formation of ocean crust. We report here geochemical results on samples collected in 2009 from the four segments closest to the continental breakup, from segment 1 which abuts the detachment fault responsible for continental extension on Moresby Seamount in the West, to segment 4, representing mature oceanic crust in the East. A total of 208 glass samples have been analyzed for their major (EMPA) and trace element (LA-ICPMS) compositions. The data show strong E-W variations. Samples ranging from tholeiitic basalt and basaltic andesite to andesite and rhyolite are found on Segment 1. They have generally high alkali values and a wide range of trace element contents and ratios. Segments 2 to 4 magmas in contrast only comprise tholeiitic basalt with lower alkali contents and a more restricted range of trace element chemistry. The geochemical differences between the segments cannot be attributed to differentiation processes alone, and different sources are required. High Ba/La, (La/Sm)N, Rb/Sr, and Th/La on Segment 1 suggest a derivation from an enriched mantle source, while low Nd/Pb and Nb/U suggest that some of the enrichment may also reflect the influence of continental crust during magma genesis. Whether this continental signature is present in the form of recycled material in the mantle or as rafted continental blocks in the axial region is at present unclear. In contrast to rocks from segment 1, trace element compositions of volcanic glasses from segments 2 to 4 show a stronger MORB signature, presumably reflecting more mature spreading in this part of the basin. The influence of continental material appears to be minimal, suggesting that uncontaminated asthenosphere quickly flows into the rift and/or that continental blocks are not retained in the axial region for long time periods following the rifting-spreading transition.

Description: EGU2010-13373 The frequency of volcanic activity varies on a wide rangeof spatial and temporal scales, from 〈1 yr. periodicities in single volcanic systems to periodicities of 106 yrs. in global volcanism. The causes of these periodicities are poorly understood although the long-term global variations are likely linked to plate-tectonic processes. Here we present evidence for temporal changes in eruption frequencies at an intermediate time scale (104 yrs.) using the Pleistocene to recent records of widespread tephras of sub-Plinian to Plinian, and occasionally co-ignimbrite origin, along the Pacific Ring of Fire, which accounts for about half of the global length of 44,000 km of active subduction. Eruptions at arc volcanoes tend to be highly explosive and the well-preserved tephra records from the ocean floor can be assumed to be representative of how eruption frequencies varied with time. Volcanic activity along the Pacific Ring of Fire evolved through alternating phases of high and low frequency; although there is modulation by local and regional geologic conditions, these variations have a statistically significant periodicity of 43 ka that overlaps with the temporal variation in the obliquity of the Earth’s rotation axis, an orbital parameter that also exerts a strong control on global climate changes. This may suggest that the frequency of volcanic activity is controlled by effects of global climate changes. However, the strongest physical effects of climate change occur at 100 ka periods which are not seen in the volcanic record. We therefore propose that the frequency of volcanic activity is directly influenced by minute changes in the tidal forces induced by the varying obliquity resulting in long-period gravitational disturbances acting on the upper mantle.

Description: EGU2010-10518 Seafloor compliance is the transfer function between pressure and vertical displacement at the seafloor Infragravity waves in the oceanic layer have long periods in the range of 30 – 500 s and obey a simple frequencywavenumber relation. Seafloor compliance from infragravity waves can be analyzed with single station recordings to determinate sub-seafloor shear wave velocities. Previous studies in the Pacific Ocean have demonstrated that reliable near-surface shear wave profiles can be derived from infragravity wave compliance. However, these studies indicate that, beside the water depth the compliance measurements are limited by instrument sensitivity, calibration uncertainties and possibly other effects. In this work seafloor compliance and infragravity waves are observed at two different locations in the Atlantic Ocean: the Logatchev hydrothermal field at the Mid Atlantic Ridge and the Azores (Sao Miguel Island). The data was acquired with the broadband ocean compliance station developed at the University of Hamburg as well as ocean station from the German instrument pool for amphibian seismology (DEPAS) equipped with broadband seismometers and pressure sensors. Vertical velocity and pressure data were used to calculate power spectral densities and normalized compliance along two profiles (one in each location). Power spectral densities show a dominant peak at low frequencies (0.01-0.035Hz) limited by the expected cut-off frequency, which is dependent on the water depth at each station. The peak has been interpreted as a strong infragravity wave with values between 10-14 and 10-11 (m/s2)2/Hz and 104 and 106 (Pa2)2/Hz for acceleration and pressure respectively. The results show compliance values between 10-10 and 10-8 1/Pa and its estimations take into account the coherence between seismic and pressure signals in order to confirm that the seismic signals in the infragravity waves are caused by pressure sources. Shear wave velocity models, with depth resolution from 200 to 2500 m for the deep water stations, were derived from compliance. Preliminary results indicate shear wave velocity increasing from 200 to 3500 m/s.

Description: EGU2010-9841 Active mud volcanoes, where changing salinities of pore fluids, large temperature gradients and occurrences of free gas are frequently observed, should potentially exhibit significant variability in their internal resistivity structure. This is due to the fact that the bulk resistivity is mainly determined by the porosity of sediments and the electrical resistivity of the pore filling contained therein. The resistivity variations may be derived from controlled source electromagnetic (CSEM) measurements. CSEM systems consist of an electric dipole transmitter producing a time varying source field and electric dipole receivers, which measure the earth´s response to this signal. For a RWE Dea funded investigation of fluid and gas leakages at the North Alex Mud Volcano (NAMV) - a comparatively small target with an area of about 1km2 - we have developed a new high resolution CSEM system. The system consists of several autonomous electric dipole receivers and a lightweight electric dipole transmitter, which can be mounted on a small remotely operated underwater vehicle (ROV). The use of a ROV allows for a precise placement of the transmitter, which is a necessary prerequisite for the investigation of such a small target. Furthermore, electromagnetic signals may be transmitted from different directions with respect to the stationary receivers, allowing for a 3D-style tomographic experiment. In this experiment, ten receivers were deployed over the surface of NAMV at a total of 16 receiver locations. During three successful dives with a Cherokee ROV (Ghent University, Belgium), the transmitter was deployed at a total of 80 locations. Here we present first quantitative results consisting of apparent resistivity estimations from the CSEM time domain data for each transmitter-receiver pair. The apparent resistivity map shows that the NAMV indeed has a heterogeneous resistivity structure with apparent resistivities varying by at least a factor of two: low apparent resistivities (~ 0.8Ωm) are found towards the center of the MV, whereas higher apparent resistivities (~ 1.6Ωm) prevail away from the center. In a second step, we interpret the time-domain data based on 1D inversions. Good data fits can be achieved by models containing 2-3 layers. Generally, the models indicate low resistivities at the surface, which can be associated with penetrating salt water and/or high temperatures. Toward greater depths, increasing resistivities presumably are due to a combination of compaction of sediments (i.e. reduced pore space), an increased presence of fresh water and possible occurrences of free gas. For some 1D models, the increase in resistivity exceeds a factor of 10 or more and layer interfaces are indicated down to depths of up to 70m. The derived resistivity variations observed at the NAMV will be interpreted in conjunction with temperature (Feseker, this session), fluid flow (Brückmann et al., this session) and seismic data (Bialas et al., this session) acquired. Temperature variations measured in the upper few meters are related to fluid flow, where high temperatures are indicative of upwelling fluids of low salinity and low temperature of either a downward flow of saline fluids or no flow activity. This type of surface measurement constitutes an integrative fluid flow gauge, which we can resolve vertically with our resistivity models. Seismic data yield a background structure to our resistivity model. New analysis of seismic data shows that seismic activity may also be linked to fluid flow activity, which we aim to match with resistivity variations and oscillations, which were observed in the electric and magnetic fields (Lefeldt et al., this session).

Description: Recently Hathorne et al. (2009) documented large intratest trace element (TE) variations in planktonic foraminifera from a single sediment trap sample that could not be explained by variations in water column properties. The laser ablation ICP-MS depth profiles of trace elements through the test walls revealed strong positive correlations between Li, Mg, Mn and Ba resulting from the mixing of a lower TE outer calcite with a higher TE inner calcite. In contrast Sr/Ca ratios remained relatively constant throughout the test wall. These intratest TE variations likely result from biomineralization processes and therefore should be explained by any valid biomineralization model. However, changes in calcite precipitation rate, crystal structure, or the chemical composition of the internal calcification reservoir could not, by themselves, fully account for the pattern of cation intratest variability. Here I expand on this work and investigate if a model of coral biomineralization by Sinclair and Risk (2006) can be adapted to explain the pattern of intratest TE variability in foraminifera. It is clear that the low Mg calcite secreting foraminifera must reduce the Mg/Ca ratio of the calcifying solution by at least a factor of 10 (e.g. Hathorne et al., 2009) and it has been suggested this is achieved by active removal of Mg from the calcification reservoir, although the actual mechanisms remain debatable (e.g. Bentov and Erez, 2006). However, a recent study of the calcification of a low Mg calcite species in the laboratory found a large shortcoming in the amount of Ca potentially provided by seawater transported to the site of calcification in vacuoles compared to a conservative estimate of the amount required to form the new calcite wall (de Nooijer et al., 2009a). This suggests active Ca transport to the site of calcification is required to provide sufficient Ca. If Ca specific, this Ca addition would effectively dilute the TE content (including Mg) of the calcification reservoir to varying degrees and potentially cause the positive TE correlations seen across the test wall. Sinclair and Risk (2006) used this dilution model to successfully explain some TE correlations in coral skeletons. This model can be effectively adapted to foraminifera as it accounts for recent observations of foraminiferal calcification including the transport of seawater by liquid endocytosis to the calcification site and an elevated pH at the site of calcification (Bentov et al., 2009; de Nooijer et al., 2009a, 2009b). This model therefore provides a powerful tool with which to integrate constraints from experimental observation with those from micro-analytical measurements to improve the accuracy, precision and scale of the palaepalaeoceanographic application of foraminiferal geochemistry. Bentov and Erez (2006) Geochem. Geophys. Gepsyst. 7, Q01P08. Bentov et al. (2009) PNAS 106, 21500. de Nooijer et al. (2009a) Biogeosciences 6, 2669. de Nooijer et al. (2009b) PNAS 106, 15374. Hathorne et al. (2009) Paleoceanography 24, PA4204. Sinclair and Risk (2006) Geochim. Cosmochim. Acta 70, 3855.

Description: We present Mg/Ca analyses performed via a Flow Through sequential dissolution device connected to an ICP-OES on the planktonic foraminifer Globorotalia inflata. The aim of the study is to explore the possibility to reconstruct the thermal gradient in the water column by separating non-crusted and crusted calcite phases in the tests of G. inflata using the difference between their Mg/Ca ratios as a measure of the thermal gradient. An important assumption is that the non-crusted part of the tests is calcified in shallow, warmer water than the crusted part. For analyses a range of different preparation steps were used to determine the ideal way of separating the phases. Foraminifer tests were (not) cleaned, (not) crushed, and (not) pulverized before online analysis with the FT device. To analyze samples with a FT device the foraminifer tests are placed on a filter with a mesh of 0.45 μm preventing clay minerals to wash through. A sequential dissolution protocol first rinses the samples with buffered Seralpur water before QD HNO3 is added in small steps to create a ramp of increasing acid strength. As acid is kept constant at each concentration for several minutes, dissolution of a specific calcite phase can take place. Initial results show that it is most effective to slightly crush the tests without applying standard cleaning procedures, but rather analyze them without cleaning. Samples were selected from the South Atlantic (core tops and specific downcore samples) and the Mediteterranean (plankton tows). All samples were chosen based on previous work on them to provide comparison with routinely analysed Mg/Ca ratios. The South Atlantic samples have been analyzed extensively as bulk samples separated in difference size fractions and crusted vs. non-crusted (Groeneveld and Chiessi). The Mediterranean samples were not only analyzed as bulk samples but also by Laser Ablation ICP-MS (von Raden et al.). Results show that bulk analyses are reliably reproduced by the FT method, especially for samples which are dominated by crusted calcite. Samples which were uncrusted often gave much higher Mg/Ca ratios than the bulk analyses. These higher Mg/Ca ratios mainly occur in the plankton tow samples and were also identified with Laser Ablation ICP-MS. A possible reason for this could be the presence of a high Mg amorphous calcite layer on the outside of foraminifer tests which have not completed their calcification yet as was recently also pointed out in several other studies. Identification of the crusted and uncrusted phases, and therewith a thermal gradient, seems to give the expected differences but a more rigorous statistical treatment is needed to pinpoint singular dissolution phases.

Description: EGU2010-2934 The exploration of the arctic seas require an integrated approach applying different infrastructures. In Fall 2009 German and Russian scientists performed a geo marine cruise off Kamchatka and in the western Bering Sea within the frame of the KALMAR-Project. Two main research subjects formed the scientific backbone of the cruise: The first objective focuses on the geodynamic and volcanological magmatic development of the Kuril-Kamchatka island arc system and the Kamchatka Aleutean Islands Triple-Junction. Very little is known about the composition of the mantle and the oceanic crust as well as of the seamounts including their ages. The best studied site is the Volcanologist’s Massif located between the Bering- and the Alpha Fracture Zone (Tsvetkov 1990, Volynets et al. 1992, Yogodzinsky et al. 1994), which structurally belongs to the Komandorsky Basin. The oldest rocks of the Volcanologist´s Massif show very similar trace element and isotope signatures like those rocks cropping out in the volcanoes on Kamchatka in the prolongation of the Alpha Fracture Zone (Portnyagin et al. 2005a), indicating similar conditions of magma formation. The top of the Volcanologist´s Massif is characterized by the young (〈 0.5 Ma) and hydrothermally active Piip volcano, which consists of special magnesium rich andesites ("Piip type"). Another hot site was the Meiji-Seamount which is the northernmost Seamount of the hotspot spur of the Hawaii-Emperor-Seamount chain, having an age of probably 〉 85 Ma. The only existing basement rocks from this seamount were gained during DSDP Leg 19. These are basalts with MORB like trace element and isotope signatures (Keller et al. 2000, Regelous et al. 2003). These data indicate that the Hawaii-Hotspot was at a MOR in Cretaceous time and that large volumes of depleted mantle material played a´role during the magma formation. The second objective focuses on paleo-oceanographic investigations concentrating on the sediments along the eastern continental slope of Kamchatka, in the Komandorsky Basin, and on the Shirshov Ridge in order to explore paleoclimate archives to better understand the subpolar water mass transfer and the oceanographic and climatic development in the subarctic NW-Pacific. Comparisons of Late Pleistocene and Holocene temperature changes within the near surface water masses between the NW-Pacific and the N-Atlantic resulted in a new hypothesis, the "Atlantic-Pacific seesaw" (Kiefer et al. 2001, Kim et al. 2004, Kiefer and Kienast, 2005). This Atlantic-Pacific pattern of opposite temperature variations dominates the last 60ka on millennial timescales. Modelling results of Saenko et al. (2004) support the hypothesis of the "Atlantic-Pacific seesaw" and they postulate a mechanistic connection between the two regions driven by salinity variations, which couples both regions through the thermohaline circulation. A different model relates the Holocene Atlantic-Pacific dipole to the atmospheric tele-connection between the Arctic Oscillation/N-Atlantic Oscillation and the Pacific N-American Oscillation (Kim et al. 2004). http://kalmar.ifm-geomar.de

Description: In March 2007 the sea floor drill rig MeBo (short for “Meeresboden-Bohrgerät”, ‘sea floor drill rig’ in German) returned from a 17-day scientific cruise with the new German research vessel Maria S. Merian. Four sites between 350 m and 1700 m water depth were sampled at the continental slope off Morocco by push coring and rotary drilling. Up to 41.5-m-long sediment cores were recovered from Miocene, Pliocene, and Pleistocene marls. MeBo bridges the gap between conventional sampling methods from standard multipurpose research vessels (gravity corer, piston corer, dredges) and drill ships. Most bigger research vessels will be able to support deployment of the MeBo. Since the drill system can be easily transported within 20-ft containers, worldwide operation from vessels of opportunity is possible. With the MeBo a new system is available for marine geosciences that allows the recovery of high quality samples from soft sediments and hard rock from the deep sea without relying on the services of expensive drilling vessels.

Description: To reconstruct the deep-water circulation for the last 3.5 Ma from deep-sea sediments of the eastern equatorial Atlantic, sea floor morphology, sub-bottom reflectors and the echo character have been mapped on the basis of 3.5 kHz records and sediment cores. Physical properties of sediments and synthetic seismograms derived from them enable us to decipher reflector sequences in environments of pelagic, currentresuspended and turbidity sedimentation. The individual reflectors originate from carbonate dissolution, hiatuses, coarse sand layers and interferences. Those which are related to carbonate dissolution and hiatuses provide evidence of water-mass boundaries by their distribution. Five phases of different deep-water circulation can be seen in the record of the last 3.5 Ma, and these are related to climate history: 1. Between 3.7 Ma and 2.2 Ma a strong deep-water circulation indicates a northward flow of bottom water below 4200 m (AABW = Antarctic - Bottom Water) and a southward flow of deep-water above 4200 m (NADW = North-Atlantic Deep Water). 2. Between 1.6 and 1.4 Ma a southward flow of bottom water below 4500 m and a diminished southward flow above 4500 m can be detected. This water-mass geometry can be interpreted by an expansion of the NADW-masses and a displacement of the AABW-masses during the same time. 3. Since 1.4 Ma a northward flow of a bottom-water current developed again. This current flow created a leeside sediment ridge in the southern part of the Kane Gap and furrows in the northern part of it. 4. Beetween 400,000 and 200,000 yrs B. P. the oceanic and atmospheric circulation increased. The strengthened oceanic circulation caused an increase in carbonate dissolution, which is documented by a traceable reflector from 2800 m to 4500 m water depth. At the same time an increase of the atmospheric circulation caused a drastic rise in the pelagic sediment accumulation (〉 100%) through an intensification of upwelling. This runs parallel with a higher oceanic productivity in the northern equatorial divergence zone and an enhanced supply of fluvial and probably eolian sediments from Senegal and Guinea. 5. Before 10,000 yrs B.P. an erosive northward flowing bottom-water current prevailed below 4500 m water depth. After 10,000 yrs B.P. the bottom-water flow was sluggish and non erosive.

Description: Based on the faunal record of planktonic foraminifers in three long gravity sediment cores from the eastern equatorial Atlantic, the sea-surface temperature history over the last 750,000 years was studied at a resolution of 3,000 to 10,000 years. Detailed oxygen-isotope and paleomagnetic stratigraphy helped to identify the following major faunal events: Globorotaloides hexagonus and Globorotalia tumida flexuosa became extinct in the eastern tropical Atlantic at the isotope stage 4/5 boundary, now dated at 68,000 years B.P. The persistent occurrence of the pink variety of Globigerinoides ntber started during the late stage 12 at 410,000 years B.P. CARTUNE-age. This datum may provide an easily detectible fauna! stratigraphic marker for the mid-Brunhes Chron. The updated scheme of the Ericson zones helped the recognition of a hiatus at the northwestern slope of the Sierra Leone Basin covering oxygen-isotope stages 10 to 12. Classifying the planktonic foraminifer counts into six faunal assemblages, according to the factor analysis derived model of PFLAUMANN (1985), the tropical and the tropical-upwelling communities account for 57% at Site 16415, and 86% at Site 13519, respectively of the variance of the faunal record. A largely continuous paleotemperature record for both winter and summer seasons was obtained from the top of the Sierra Leone Rise with the winter temperatures ranging between 20 and 25° C, and the summer ones between 24 and 30° C. The record of cores from greater water depths is frequently interrupted by samples with no-analogue faun al communities and/or poor preservation. Based on the seasonality signal, during cold periods the thermal equator shifted to a geographically more asymmetrical northern position. Dissolution altering the faunal communities becomes stronger with greater water depth, the estimated mean minimum loss of specimens increases from 70% to 80% between 2,860 and 3,850 m water depth although some species will be more susceptible than others. Enhanced dissolution occurred during stage 4 but also during cold phases in the warm stages 7 and 9. Correlations between the Foraminiferal Dissolution Index and the estimated sea-surface temperatures are insignificant. Foraminiferal flux rates, negatively correlated to the flux rates of organic carbon and of diatoms, may be a result of enhanced dissolution during cold stages, destroying still more of the faunal signal than indicated by the calculated minimum loss. The fluctuations of the oxygen-isotope curves and the hibernal sea-surface temperatures are fairly coherent. During warm oxygen-isotope stages the temperature maxima lag often by 5 to 15 ka behind the respective isotope minima. during cold stages, sea-surface temperature changes are partly out of phase and contain additional fluctuations.

Description: Over 100 samples of recent surface sediments from the bottom of the Atlantic Ocean offshore of NW Africa between 34° and 6° N have been analysed palynologically. The objective of this study was to reveal the relation between source areas, transport systems, and resulting distribution patterns of pollen and spores in marine sediments off NW Africa, in order to lay a sound foundation for the interpretation of pollen records of marine cores from this area. The clear zonation of the NW-African vegetation (due to the distinct climatic gradient) is helpful in determining main source areas, and the presence of some major wind belts facilitates the registration of the average course of wind trajectories. The present circulation pattern is driven by the intertropical front (ITCZ) which shifts over the continent between c. 22° N (summer position) and c. 4° N (winter position) in the course of the year. Determination of the period of main pollen release and the average atmospheric circulation pattern effective at that time of the year is of prime importance. The distribution patterns in recent marine sediments of pollen of a series of genera and families appear to record climatological/ecological variables, such as the trajectory of the NE trade, January trades, African Easterly Jet (Saharan Air Layer), the northernmost and southernmost positions of the intertropical convergence zone, and the extent and latitudinal situation of the NW-African vegetation belts. Pollen analysis of a series of dated deep-sea cores taken between c. 35° N and the equator off NW Africa enable the construction of palaeo-distribution maps for time slices of the past, forming a register of palaeoclimatological/palaeoecological information.

Description: Molybdenum and vanadium were analysed in 9 sediment cores recovered from the continental slope and rise off NW Africa. additional chemical and sedimentological parameters as well as isotope stage boundaries were available for the same core profiles from other investigations. Molybdenum, ranging between 〈 1 and 10 ppm, occurs in two associations, either with organic carbon and sulphides in sediments with reducing conditions or with Mn oxides in oxidized near-surface core sections. Highest values (between 4 and 10 ppm Mo) are found in sulphide-rich core sections deposited during glacial times in a core from 200 m water depth. The possibility of anoxic near-bottom water conditions prevailing at this site during certain glacial intervals is discussed. In oxidized near-surface core sections, the diagenetic mobility of Mo becomes evident from strong Mo enrichment together with Mn oxides (values up to 4 ppm Mo). This enrichment is probably due to coprecipitation and/or adsorption of Mo from interstitial water to the diagenetically forming Mn oxides. The close relation between Mo and Corg results in strongly covarying sedimentation rates in both components reaching up to 10 times the rates in glacial compared to interglacial core sections. Vanadium (values between 20 and 100 ppm) does not show clear relations to climate and near-bottom or sediment milieu. It occurs mainly bound to the fine grained terrigenous fraction, associated with aluminium silicates (clay minerals) and iron oxides. Additionally positive covariation of vanadium with phosphorus in most core profiles suggest that some V may be bound to phosphates.

Description: A statistical analysis of 15 deep sea cores in the eastern North Atlantic off NW Africa revealed the typical fluctuation pattern of distinct species groups as has been described from various parts of the world ocean. Only the "WBF-group" appears to be correlated with global climatic changes, i.e. warmer periods as the Eemian and the Atlanticum. A partly antagonistic "High Productivity group" (HPR-group) is in general not linked with global changes but times of increased fertility in the surface water and the resulting flux of organic matter reaching the bottom. The groups were extracted from cluster analysis of more than 150 surface samples (HPR-group, LuTZE & CouLBOURN 1984) and a factor analysis of selected cores (WBF-group). In contrast to previous studies the observed fluctuations can not be explained by drastic changes in bottom water masses, but by the pulsation of a distinct "High Productivity Patch" in space and time. At present, this patch is located below the well known upwelling area between 22° and 12° northern latitude. It shifted to the north (up to 27° N) during the latest glacial period (18 ky), indicating an equivalent shift of upwelling productivity caused by advection of nutrient rich upwelling SACW-waters, probably during most of isotopic stages 2 and 3.

Description: A considerable number of samples recently obtained from the collections of the German research vessels "Meteor" and "Valdivia" in the eastern North Atlantic have been evaluated for their planktonic foraminiferal composition. The new data enabled a quantitative and qualitative improvement of the data base for a statistical analysis of planktonic foraminiferal fauna using the transfer function technique of IMBRIE & KIPP (1971). 134 modern sediment samples from the eastern North Atlantic were selected according to their excellent preservation of foraminifera and treated by a principle component analysis. The resultant six factors account for 96.7% of the variance of the original data comprising 15 major species and species groups. A multiple regression analysis between these factors and the actual mean sea-surface temperatures and salinities resulted in a set of equations. They can be applied for estimating past sea-surface winter and summer temperatures and salinities from planktonic foraminiferal assemblages for approximately the last 500,000 years. The new functions have a standard error of 1.2° C for winter and summer temperature and 0.4‰ for annual salinity.

Description: Sedimentological and geotechnical analyses were carried out on two undisturbed large diameter deep sea cores from the Antarctic sector of the Atlantic ocean. One core, from a silled basin within the Bransfield Strait is characterized by fine grained hemipelagic material and turbidite layers. The other core, from the continental slope of the Weddell Sea represents a typical glacial marine environment. The variations of physical properties as related to both an increasing overburden pressure (or depth below top of core) and/or to lithological changes are discussed. With increasing overburden pressure only small variations of physical properties were observed. In core 14882-2 the porosity decreases 0.7% per meter, the natural water content 6% per meter. The wet bulk density and the shear strength increase with rates of 0.015 g/cm3 and 0.5 KPa per meter. Compared to small variations in consolidation, the changes of the lithology cause more extreme variations of physical properties: e.g. decreases the natural water content by 100%, the porosity by 14%, and the wet bulk density increases by 0.23 g/cm3 due to a turbidite layer in the core from the Bransfield Strait (core 14882-2). In the core from the continental slope of the Weddell Sea (core 14875-1) two major unconformities have been detected. The ice-rafted debris of this core causes a generally lower porosity (64%), a lower natural water content (75%), a higher wet bulk density (1.55 g/cm3) and specific grain density (2.62 g/cm3), compared to the core from the Bransfield Strait (porosity 77% , natural water content 151% , wet bulk density 1.34 g/cm3, specific grain density 2.47 g/cm3).

Description: The "Meteor" cores 22M36 and 22M37 are situated on the eastern rim of the Mediterranean Ridge SW of the Peloponnesus at 3200 and 3350 m water depth. Core 22M37 contains a breccia consisting mainly of Upper Serravallian/Lower Tortonian claystone clasts. They are characterized by smectite-dominated clay mineral assemblages. The breccia contains displaced benthic foraminifers of neritic character and bryozoan debris. At the top of the breccia follows a chaotic stratigraphic sequence including Serravallian (?), Tortonian, Messinian, Pliocene and Pleistocene sediments. The deposits of Upper Tortonian to Pleistocene age are characterized by illite-dominated clay mineral assemblages. The smectite-dominated assemblages are very similar to that of the surface sediments from the extreme eastern part of the Levantine Basin which represent Nile-derived terrigenous material. It is speculated, that during Upper Serravallian/Lower Tortonian time mineral detritus derived from an early "Nile" may have been transported into the Ionian Sea. This would implicite a seafloor morphology different from today's (the Mediterranean Ridge prevents sediment transport into the Ionian Sea) and considerable tectonic movements since that time. The termination of the smectitedominated sedimentation in the considered area SW of the Peloponnesus would indicate the beginning of the barrier function of the Mediterranean Ridge. Such movements have to be inferred also from the neritic components of the breccia. They have to be explained by turbiditic influx. However, in the present morphology, turbidity currents starting from a shallow water region could not reach the core positions. Core 22M36, situated close to core 22M37, represents a Quaternary sequence (upper part of nannoplankton zone NN 19 to base of NN 21) with conglomeratic layers and unconformities. They point to tectonic movements within this time. The origin of the breccia as well as of the chaotic sequence in core 22M37 may have happened near the boundary of nannoplankton zones NN 19/20.

Description: From 27 Janua1y to 23 June 1979 R. V. "Meteor" surveyed the central equatorial Atlantic on a section along 22° W from 3° N to 2° S. During the observation period, a hydrographic section down to 600 m was repeated ten times with a continuous "Howaldt-Bathysonde" CTD and a rosette sampler. The station distance was 10 to 15 nm. The water samples were used to recalibrate salinity and to determine oxygen, nutrients and chlorophyll a. An undulating CTD system ("Delphin") was towed on 11 sections. A profiling distance of one to two nautical miles and a profile depth of 90 m was obtained. Five current meter arrays were moored along 22° W between 3° N and 1° S from January to March 1979. In May and June two moorings were installed at 2° N and at the equator. On the buoys measurements of wind speed and direction were obtained. At 43 stations a wire-guided Aanderaa profiling current meter was successfully lowered. Drifting buoy experiments were repeated three times with clusters of 5 to 10 buoys. A fourth experiment took place in 1978 in the Gulf of Guinea. On the way from and to port XBT sections were carried out. The data sets obtained by these instruments are presented in this data report.

Description: Along the Sierra Leone continental shelf edge, bedded rocks, presumably mostly calcareous sandstone, calcarenites and siltstones form exposures up to 10 km long in water depths ranging from 80 to 110 m. These outcrops are found in a 6 km broad zone along the shelf edge; landward they get covered by recent shelf sands. Their apparent strike direction parallds the shelf edge indicating nearly horizontal bedding which locally is interrupted by faulting. On the middle shelf, a terrace is well developed at a water depth of 56 m. Ripples, megaripples, pockmarks 1-5 m in diameter, and canyon-heads form other significant features of the shelf.

Description: The sediments of a 10.67 m long piston core recovered from the Sierra Leone Rise ("Meteor" Core 13519) have been analysed for their paleomagnetic properties. Using detailed demagnetization techniques, the geomagnetic Brunhes/Matuyama boundary could be identified between 9.81 and 9.89 m sub-bottom. This is in excellent agreement with the oxygen isotope stratigraphy by SARNTHEIN et al., this volume. Down to this level, therefore, the average apparent accumulation rate amounts to 13.5 m/m.y. assuming an age of 0.73 m.y. for the reversal boundary (BERGGREN et al. 1983). A second transition in magnetization polarity was recognized between 10.51 and 10.54 m sub-bottom. According to its magnetic signature it was tentatively correlated to the beginning of the Jaramillo event (0.98 m.y.). This would imply that in the lowermost part of the core the apparent accumulation rate decreases to less than 20% of that found in the upper sequences. However, as obviously only a small portion of the Jaramillo event is recorded in the sediment column, a more plausible solution is to keep the overall sedimentation rate about constant by introducing a hiatus of some 2·105 years shortly after the lower Jaramillo/Matuyama reversal boundary. Alternative interpretations are also discussed.

Description: From a 10.7 m long gravity core from the Sierra Leone Rise (5° 39,5' N, 19° 51'W) a detailed oxygen and carbon isotope record of both planktonic and benthonic foraminifera species was obtained extending from the Recent to the Jaramillo event. The analysis yielded six major results. 1. Benthos oxygen isotopes varied by 1.8-2.2‰ from interglacial to glacial times and may indicate a synglacial cooling of North Atlantic Deep Water at 2800 m depth by 1-3° C. 2. Variable anomalies between the benthos and plankton δ18 O record indicate a cooling of sea-surface temperatures (SST) by up to 6° C during some glacial stages. 3. Southerly trade winds and equatorial upwelling may exert the primary control of SST variations, in particular of extreme values of cold and warm stages and of the abrupt character of climate transitions and their leads and lags, and finally, of variable sedimentation rates. 4. The benthos δ13C record correlates well with the flux and preservation of organic matter. 5. A new time scale, CARPOR, was established from the assumption that terrigenous sediment supply was ± constant but CaC03 varied considerably. When applied to the δ18O record, three major and numerous short-term variations of sedimentation rates (0.8 to 4.0 cm/kyr) can be distinguished. 6. The climatic record was modified by bioturbation much more strongly during cold than during warm stages.

Description: Planktonic foraminiferal tests of the spinose species Orbulina universa, of the non-spinose Globorotalia tumida-menardii complex, and of a mixed species assemblage (grain size fraction 200-400 μm) were isolated from Sierra Leone Rise core 13 519-2 and analyzed for free, total, and bound (by difference) amino acids to study the isoleucine epimerization mechanism in fossil foraminiferal tests and to define empirical calibration curves for dating deep-sea sediments over the past 900,000 years. Total isoleucine epimerization curves typically separate into three "linear" segments of decreasing apparent rates with increasing time and exhibit a pronounced "species effect". The degree of epimerization attained at time is considerably lower in 0. universa than in G. tumida-menardii while the mixed species results scatter between the limits delineated by the two monospecific curves. Total allo/iso ratios are closely related to the proportion of free to total isoleucine accumulating in the tests indicating that the rate of hydrolysis of matrix proteins and peptides controls the overall epimerization reaction. The results are consistent with experimental evidence (KRIAUSAKUL & M1TTERER 1978, 1980 a, b) whereupon isoleucine epimerizes at a rapid rate in terminal positions but at slow rates in interior positions as well as in the free state. Notwithstanding free isoleucine exhibits the highest degree of epimerization due to preferential hydrolysis of extensively epimerized terminal isoleucine. Species-specific hydrolysis and epimerization rates are maintained until about 50% of bound isoleucine have been hydrolyzed to the free state corresponding to a total allo/iso ratio of about 0.5. Remaining peptide units appear to be more resistent against hydrolysis and separate species then show the same apparent epimerization rate dominantly controlled by the slow conversion rate in the free state until equilibrium is achieved in Miocene samples under deep-ocean temperature conditions (KING & HARE 1972 a). The degree of epimerization attained at comparable time in separate species will, however, remain different due to different initial rates of hydrolysis. Selective leaching of free isoleucine from the tests results in a lowering of total allo/iso ratios and apparent rate constants when significant amounts have been generated by diagenetic hydrolysis. Comparison with results based on Pacific core V 28-238 (KING & NEVILLE 1977) indicates an inverse relationship between the intensity of surficial carbonate dissolution and post-depositional leaching. Tests deposited under less corrosive conditions (Atlantic core 13519-2) will more significantly deviate from a closed system during diagenesis than those deposited in more corrosive bottom waters (Pacific core V 28-238). Carbonate dissolution removes proteinaceous lamellae from more external shell structures, which otherwise - if preserved during deposition - will preferentially be subject to leaching of free amino acids during diagenesis. This effect may qualify the applicability of empirical epimerization calibration curves to different depositional environments although the general agreement of the epimerization curves obtained for both sites is promising for future research. Identical apparent epimerization rates in G. tumidamenardii tests younger than 120,000 years (when leaching is stiH insignificant) at both Atlantic and Pacific sites are not consistent with the presently different bottom water temperatures in these regions. It is concluded that glacial North Atlantic Deep Water was cooler than at the present at the Sierra Leone Rise.

Description: Measurements by CTDs (Multisonde, Bathysonde) and current profilers were carried out onboard the research vessels "Meteor" and "Planet" during the Joint Air-Sea Interaction Project (JASIN) in 1978. Data from these observations are presented in the form of mean distributions with their standard deviations, as time series and as profiles during the "multiship experiments". Selected time series of terms derived from the data are added: current shear, Vaisala frequency and Richardson Number. The text also contains information concerning instrument calibration and data processing.

Description: The three Federal German research vessels "Planet", "Meteor" and "Poseidon" participated in the Second Multiship Experiment during JASIN 1978 as stationary ships with CTD yo-yo profiling. The analysis is concerned mainly with the weakly stratified layer between the seasonal thermocline and the turbulent mixed layer. The thermoclinic structure of a front in that layer and its tidal/inertial displacement is described and is shown to be in accordance with current meter data from the H2 mooring. It is shown that the CTD yo-yos cannot be treated as pure time-series but that the movement of the ships relative to the seabed and relative to the front has to be taken into account. The method of isopycnic analysis was used to eliminate the effect of internal waves. Temporal coordinates can be converted to spatial coordinates allowing for the tidal/inertial movements. Thus high resolution sections through the front can be given. The thermohaline structure is described on density levels in the seasonal thermocline and in the weakly stratified layer above it.

Description: We present field measurements of air-sea gas exchange by the radon deficit method that were carried out during JASIN 1978 (NE Atlantic) and FGGE 1979 (Equatorial Atlantic). Both experiments comprised repeated deficit measurements at mixed position over periods of days or longer, using a previously described precise and fast-acquisition, automatic radon measuring system. The deficit time series exhibit variations that only partly reflect the expected changes in gas transfer. By evaluating averages over each time series we deduce the following average gas transfer velocities (average wind velocity and water temperature in parentheses): JASIN phase 1: 1.6 ± 0.8 mid (at -6 mis, 13 °C) JASIN phase 2: 4.3 ± 1.2 mid (at -8 mis, 13 °C) FGGE: 1.2 ± 0.4 mid (at -5 mis, 28 °C) 0.9 ± 0.4 mid (at -7 mis, 28 °C) 1.5 ± 0.4 mid (at -7 mis, 28 °C) The large difference between the JASIN phase 2 and FGGE values despite quite similar average wind velocity becomes even larger when the values are corrected to a common temperature. Both values are, however, fully compatible with the range of gas transfer velocities observed in laboratory experiments and the conclusion is suggested that their difference is caused by the highly different wind variability in JASIN and FGGE. We conclude that in gas exchange parameterization it is not sufficient to consider wind velocity only. A comparison of our observations with laboratory results outlines the range of variation of air-sea gas transfer velocities with wind velocity and sea state. We also reformulate the radon deficit method, in the light of our observed deficit variations, to account explicitely for non-stationarity and horizontal inhomogeneity in the near-surface radon deficit layer (i.e., mixed-layer and upper thermocline). We show that neglection of non-stationarity and horizontal inhomogeneity in previous radon work introduces considerable uncertainty in deduced gas transfer velocities. We furthermore discuss the observational requirements that have to be met for an adequate exploitation of the radon deficit method, of which an observation area of minimum horizontal inhomogeneity and monitoring of the remaining inhomogeneities are thought to be the most stringent ones.

Description: Data from two current meter moorings and thermosa�linograph records from the Scotia Sea are presented. Results from the first mooring site demonstrate the ex�change of Antarctic Bottom Water between the northern Scotia Sea and the Argentine Basin. The sec�ond current data set illustrates the permanent deep counter current on the continental rise of the southern Drake Passage. Surface temperature and salinity rec�ords describe the position of the Polar Front and the Weddell-Scotia-Confluence during early austral sum�mer 1980/81.

Description: Seven cores from the West-African continental margin in 12-18° N have been investigated by means of a coarse fraction analysis. Four of the seven cores contain allochthonous material: turbidites and debris flow deposits. The source of the allochthonous material is in about 300-600 m water depth. The age of the slide induced debris flow deposits is at the end of oxygen isotope stage 2. One debris flow deposit is covered by a turbidite (core 13211). The turbidites in the deep-sea core 13207 originate from river-influenced sediments from the West-African continental margin, whereas the autochthonous sequences are influenced by volcanic material from the Cape Verde Islands. Particle by particle supply from upper slope areas has been found in all four cores from the continental slope. Current sorting occurs on the submarine diapir (core 89), whereas core 91 on the NW-flanc, 200 m below core 89, has no current sorting, except for stage 1 and parts of stage 5. The current sorting is reflected by parallel variations of median diameters of whole tests and of fragments of planktonic foraminifers, by higher median diameters of foraminifers on top of the diapir, by reduced accumulation rates and increased sand fraction percentages in core 89 compared to core 91. The Late Quarternary climatic history of the West-African near coastal area (12-18° N) has been redrawn (Fig. 10): - in oxygen isotope stage 1 a humid climate is found in 12-18° N (This "humid impression" in 18° N, which is actually an arid area, is due to the poleward directed undercurrent, which transports Senegal river material to the north). - in oxygen isotope stage 2 an arid climate existed in 14-18° N, whereas in 12° N river discharge persisted. But within stage 2 dune formation occurred in 12° N on the (dry) shelf, additionally to fluviatile sediment input. - Older periods are preserved in autochthonous sediments of core 89 and 91, where oxygen stages 3, 5 and 7 (the latter only in core 89 present) show a humid climate (as well as in stage 5 of core 55), interrupted by short arid intervals in core 89, and stage 4 and 6 show an arid climate, interrupted by short humid periods (s. Fig. 10). The allochthonous stage 5 sediment in core 11 also reflects a humid climate. The dissolution of planktonic foraminifers is strongest in the Late Holocene and shows a minimum in the Early Holocene, where also pteropods are preserved. The degree of carbonate dissolution is related mainly to the fine matter content (〈 63 μm) (Fig. 11) whereas water depth is a less decisive factor.

Description: Foraminifera shells from modern sediments document the hydrography of the coastal upwelling region off Northwest-Africa (12-35° N) through the stable isotopic composition of their shells. Oxygen isotopes in planktonic foraminifers reflect sea-surface temperatures (SST) during the main growing season of the different species: Globigerinoides ruber (pink and white) and G. sacculifer delineate the temperatures of the summer, Globorotalia inflata and Pulleniatina obliquiloculata those of the winter. Oxygen isotopes in Globigerina bitlloides document temperature ranges of the upwelling seasons. δ18O values in planktonic foraminifera from plankton hauls resemble those from surface sediment samples, if the time of the plankton collection is identical with that of the main growing season of the species. The combined isotopic record of G. ruber (white) and G. inflata clearly reveals the latitudinal variations of the annual mean SST. The deviation of the δ18O values from both species from their common mean is a scale for the seasonality, i.e. the maximum temperature range within one year. Thus in the summer upwelling region (north of 25° N) seasonality is relatively low, while it becomes high in the winter upwelling region south of 20° N. Furthermore, the winter upwelling region is characterized by relatively high δ18O values - indicating low temperatures - in G. bulloides, the region of summer upwelling by relatively low δ18O values compared with the constructed annual mean SST. Generally, carbon isotopes from plankton hauls coincide with those from sediment surface samples. The encrichment of 13C isotopes in foraminifers from areas with high primary production can be caused by the removal of 12C from the total dissolved inorganic carbon during phytoplankton blooms. It is found thatcarbon isotopes from plankton hauls off Northwest-Africa are relatively enriched in 13C compared with samples from the western Atlantic Ocean. Also shells of G. ruber (pink and white) from upwelling regions are enriched in the heavy isotope compared with regions without upwelling. In the sediment, the enrichment of 13C due to high primary production can only be seen in G. bulloides from the high fertile upwelling region south of 20° N. North of this latitude values are relatively low. An enrichment of 12C is observed in shells of G. rnber (pink), G. inflata and P. obliquiloculata from summer-, winter- and perennial upwelling regions respectively. Northern water masses can be distinguished from their southern counterparts by relatively high oxygen and carbon values in the "living" (= stained) benthic foraminifera Uvigerina sp. and Hoeglundina elegans. A tongue of Mediterranean Outflow Water can be identified far to the south (20° N) by 13C-enriched shells of these benthic foraminifera. A zone of erosion (15-25° N, 300-600 m) with a subrecent sediment surface can be mapped with the help of oxygen isotopes in "dead" benthic specimens. Comparison of δ18O values in aragonitic and calcitic benthic foraminifers does not show a differential influence of temperature on the isotopic composition in the carbonate. However, carbon isotopes reflect slight differences under the influence of temperature.

Description: In samples from the Iberian Basin and off Cape Blanc, dredged from below 2000 m, 10 species of ophiuroids were found, viz. Ophioscolex sp., Ophiambix meteoris, Amphioplus verrilli, Amphilepis sp., Ophiochiton ternispinus, Amphiophiura convexa, Ophiocten latens, Ophiura ljungmani, Ophiomusium lymani, and Ophiosphalma armigerum. The distribution of the species found is summarized. The descriptions of Amphioplus verrilli, Ophiochiton ternispinus, Ophiomusium lymani, and Ophiosphalma armigerum are extended. Silax pulvinus is supposed to be synonymous with Amphioplus verrilli. The genus Silax is withdrawn. Most of the genera and many of the species are cosrnopolitans. The ophiuroids found have no morphological characteristics distinguishing them as deep-sea forms.

Description: A general study of structure, biomass, and dynamic estimates on meiofauna was carried out during PREFLEX (1975) and FLEX (1976), in 117-141 m water depth. On the basis of these data an attempt was made to estimate meiofauna production, and this is discussed in relation to the energy input from the spring phytoplankton bloom. Sampling was performed at five stations, but only the stations 1, 4, and 5 were covered by a complete series from August 1975 to July 1976. At each station, from four replicate box core samples, two were withdrawn to study the abundance, distribution, and biomass of meiofauna, the content of chloroplastic pigment equivalents (CPE), and chemical and grain size analyses. At all stations grain size feil in the range of fine sand having median diameters (MD) of 〈125 μm. From Station 1 to 5 an increase in MD was observed. Highest values of CPE (7.81 μg ml-1) and organic matter (4.7%) were obtained in June and July (1976)/August (1975), respectively. Meiofauna abundance was fairly uniform at all stations examined. Station 1 displayed maximal numbers during the whole investigation period. The abundance per 100 cm2 varied between 15,550 and 34,900 organisms. All meiofauna studied both in total and as separate taxa showed annual cycles of abundance. Low abundance values were recorded during early summer, and maximum values during winter. High numbers of Foraminifera were obtained for August 1975 (9,460 per 100 cm2) and July 1976 (9,710 per 100 cm2). From December to June the values decreased from 3,280 to 1,030 per 100 cm2. At station 1 maximum values of meiofauna biomass were recorded ranging from 1.5 to 2.7 g DWT m-2. The mean meiofauna dry weight amounted to 2.1 g DWT m-2. Based on minimum production, the P/B ratio for the area of Station 1 might have a mean of 1.4. Taking into consideration generation times we believe that a turnover ratio of 2 is a conservative value for the Fladen Ground meiofauna. The annual production would amount to 4.2 g DWT m-2 yr-1. This is 27.5% of the energy supply during the spring phytoplankton bloom, which is channelled into the meiofauna. The hypothesis is put forward that the energetic strategy of deep offshore meiofauna differs distinctively from that of shallow inshore meiofauna. While the shallow inshore meiofauna show a relatively fast response to organic matter input, the deep offshore meiofauna reacts much more slowly, the food energy consumption seems to be spread out over a longer period.

Description: A general study of structure, biomass estimates and dynamics on the macrofauna was carried out in August 1975 and March 1976 during PREFLEX (1975) and FLEX (1976), the Fladen Ground Experiment. On the basis of these data an attempt was made to estimate macrobenthic production expressed as minimum production (MP). The macrobenthic production is discussed together with meiobenthic annual production (FAUBEL, HARTWIG & THIEL 1983) and with indirectly estimated microbenthic production in relation to an energy input from the water column of about 25g C m-2 year-1 (STEELE 1974). From the production estimates of the three benthic components a rough energy budget is proposed. Sampling was performed at five Stations for endofauna twice during the time of investigation and for epifauna once. At each station two replicate box core samples (30 X 20 cm) were taken for endofauna. Epifauna was sampled with an Agassiz trawl once at each Station. The total numbers of endofauna increased from station l to 5. This was valid as well for August 1975 (4,233-12,166 individuals per m2 and 10 cm sediment depth) as for March 1976 (1,008-2,925 individuals). The polychaetes were the dominant organisms with a share of 33 to 62%. The densities for the endofauna decreased from August 1975 to March 1976 by a mean factor of 2.8. Abundances of epifauna amounted to values between 11 and 102 individuals per 1000 m2. The biomass dry weights (DWT) for macrobenthic endofauna varied between 0.97g DWT m-2 and 6.42g DWT m-2 in August 1975 and between 0.27g DWT m-2 and 2.64g DWT m-2 in March 1976. The mean amounted to 1.74g DWT m-2. Dry weights of epifauna biomass gave values between 4.9 and 83.1g DWT, 1000 m-2. The minimum production for the total macro-endofauna at Fladen Ground amounted to 1.43g DWT m-2 yr-1 or 0.82g C m-2 yr-1. This resulted in a minimum turnover rate (P/B) of 0.8. The share produced by the polychaetes amounted to 1.06g DWT m-2 yr-1 or 74%.

Description: Based on more than 1800 neuston tows, the ranges and mean abundances per area of 10 taxa of beloniform fish are calculated. The distributional patterns of fry of most oceanic taxa are a consequence of both surface temperatures and direction of currents. Oxyporhamphus microptems has a strictly tropical distribution; in the centre of its distribution the mean abundance reaches 10-50 ind./1000 m2. Nanichthys simulans occurs polewards of 0. micropterus, mainly within the great warm circulation systems. Scomberesox saurus has a bipolar subtropical-temperate distribution with seasonal shift of the boundaries, and a general abundance of 30-40 ind./1000 m2, though in subtropical frontal zones values above 100 ind./1000 m2 are common. Exocoetus volitans covers the warmer parts of the Atlantic, but has two antiequatorial belts of maximum abundance within the tropics (25-35 ind./1000 m2). The other exocoetid taxa have similar poleward boundaries as E. volitans. E. obtusirostris and genus Cypselurus average 1.5 ind./1000 m2, whilst Prognichthys gibbifrons, Danichthys rondeletii and genus Hirundichthys have mean abundances of an order of 0.5 ind./1000 m2. Belone svetovidovi is strictly neritic, and shows great regional differences of abundance off NW Africa.

Description: Macro- and meiobenthic abundance and biomass as well as metabolic activity (respiration, ETS activity) have been studied along a transect ranging from 130 to 3000 m water depth off northern Morocco (35° N) during "Meteor" cruise No. 53 (1980). The distribution of chloroplastic pigment concentration (chlorophyll a, pheophytins) in the sediment has been investigated as a measure of sedimented primary organic matter. High chloroplastic pigment concentrations were found on the shelf and around the shelf break, but values declined rapidly between 200 and 600 m depth. Below 1200 m pigment concentrations remained at a relatively uniform low level. Macrobenthic abundance and biomass (wet weight) decreased with increasing water depth and with distance from the shore. Significant changes occurred between the shelf and upper slope and below 2000 m depth. Meiobenthic abundance and biomass (ash free dry weight) followed the same general pattern, but changes were found below 400 and 800 m depth. In the depth range of 1200 to 3000 m values differ only slightly. Meiofauna abundance and biomass show a good correlation with the sedimentary chloroplastic pigment concentrations. Respiratory activity of sediment cores, measured by a shipboard technique at ambient temperatures, decreased with water depth and shows a good correlation with the pigment concentrations. ETS activity was highest on the shelf and decreased with water depth, with significant changes between 200 and 400 m, and below 1200 m depth, respectively. Activity was generally highest in the top 5 cm of the sediment and was measurable, at all Stations, down to 15 cm sediment depth. Shelf and upper slope stations exhibited a vertical distribution pattern of ETS activity in the sediment column, different from that of deeper Stations. The importance of biological activity measurements as an estimate of productivity is discussed. To prove the thesis that differences in benthic abundance, biomass and activity reflect differences in pelagic surface primary production, in the case of the NW-African coast caused by different upwelling intensities, the values from 35° N were compared with data from 21° N (permanent upwelling activity) and 17° N (ca. 9 months upwelling per year). On the shelf and upper slope (〈 500 m) hydrographical conditions (currents, internal waves) influence the deposition of organic matter and cause a biomass minimum between 200 and 400 m depth in some regions. But, in general, macrobenthic abundance and biomass increases with enhanced upwelling activity and reaches a maximum in the area off Cape Blanc (21° N). On the shelf and in the shelf break region meiofauna densities are higher at 35° N in comparison to 21° N; but in contrast to the decreasing meiofauna abundance with increasing water depth at 35° N, an abundance maximum between 400 and 1200 m depth is formed in the Cape Blanc region; this maximum coincides with the maximum of sedimenta1y chloroplastic pigment equivalents. The comparison of ETS activities between 35° N and 21° N shows on the shelf activity at 21° N is up to 14 times higher and on the slope 4-9 times higher, which demonstrates that benthic activity responds to the surface productivity regime.

Description: 7 new Harpacticoidea species and the female of a known species of the family Cletodidae (Crustacea, Copepoda) new to science are dealt with in this paper. Heteropsyllus serratus n. sp. Mesocletodes trisetosa n. sp. Mesocletodes parabodini n. sp. Mesocletodes variabilis n. sp. Paranannop11s plumosus n. sp. Paranannopus langi WELLS, 1965 ♀ Metahuntemannia pseudomagniceps n. sp. Metahuntemannia atlantica n. sp. As far as possible the species relationships within each genus are discussed. All species were collected at 500 m depth on the Iceland-Faroer-Ridge.

Description: In the present paper results of taxonomic investigations on 1137 specimens of Cyllopus magellanicus DANA 1853 and of 730 specimens of Cyllopus lucasii BATE 1862 are reported. A brief diagnosis and key are given for the genus and the species. For the first time larvae of the pantochelis stage of these species are described. The habitus of the larvae are very similar, small differences were found on the structures of the pereopod 3-6. Due to special morphological similarities it is concluded that the larvae of both species display a parasitic way of life like Vibilia. The distribution of the species in the Antarctic Ocean is circumpolar: C. magellanicus occurs probably only within the West Wind Drift while C. lucasii was found within both the West and the East Wind Drift. Remarkable is the occurrence of a great number of males of C. magellanicus in the uppermost layer (30-0 cm depth), meanwhile the females of this species were found only in deeper layers.

Description: Psephitic particles in the region of the Iceland-Faeroe-Ridge have been transported and deposited by means of a complex interplay of glacier movements and drifting icebergs. The composition of the particle association is controlled by the sedimentation of basaltic rock particles derived from the ridge itself and, in addition to that and in southern parts of the ridge, from the Faeroe Islands, the Faeroe-Bank and the Bill Baileys-Bank. Besides, there are crystalline and sedimentary dropstones showing a very varied petrography and a wide range of particle sizes. Their percentage becomes greater as the distance from the ridge increases. The association of dropstones is relatively homogeneous in the region of the ridge and only at greater distances from the ridge it becomes more differentiated. Owing to their composition and distribution, as well as on the basis of characteristic fossils and rock types, the dropstones are derived from Scandinavia and Great Britain. During periods of maximum glaciation, the Iceland-Faeroe-Ridge, the Faeroe-Bank and the Bill Baileys-Bank were under ice.

Description: The aragonite compensation depth was described by pteropods in surface sediments at the northeastern Atlantic continental margin between 12° and 48° N. It rises from 3100 m up to 400 m water depth in the high-productivity zones of fertile upwelling and river discharge.

Description: Seven sediment cores from the cruises of the "Meteor" and "Valdivia" were examined palynologically. The cores were retrieved from the lower continental slope in the area of between 33.5° N and 8° N, off the West African coast. Most of the cores contain sediments from the last Glacial and Interglacial period. In some cases, the Holocene sediments are missing. Some individual cores contain sediments also from earlier Glacial and Interglacial periods. The main reason for making this palynological study was to find out the differences between the vegetation of Glacial and Interglacial periods in those parts of West Africa which at present belong to the Mediterranean zone, the Sahara and the zones of the savannas and tropical forests. In today's Mediterranean vegetation zone at core 33.5° N, forests and deciduous forests in particular, are missing during Glacial conditions. Semi-deserts are found instead of these. In the early isotope stage 1, there is a very significant development of forests which contain evergreen oaks; this is the Mediterranean type of vegetation development. The Sahara type of vegetation development is shown in four cores from between 27° N and 19° N. The differences between Glacial and Interglacial periods are very small. It must be assumed therefore that in these latitudes, both Glacial and Interglacial conditions gave rise to deserts generally. The results are in favour of a slightly more arid climate during Glacial and a more humid one during Interglacial periods. The southern boundary of the Sahara and the adjacent savannas with grassland and tropical woods were situated more to the south during the Glacial periods than they were during the Interglacial ones. In front of today's savanna belt, it can be seen from the palynological results that there are considerable differences between the vegetation of Glacial and Interglacial periods. The woods are more important in Interglacial periods. During the Glacial periods these are replaced from north to south decreasingly by grassland (savanna and rainforest type of vegetation development). The southern limit of the Sahara during stage 2 was somewhere between 12° N and 8° N which is between 1.5 and 5 degrees in latitude further south than it is today. Not only do these differences in climate and vegetation apply to the maximum of the last Glacial and for the Holocene, but they apparently apply also to the older Glacial and Interglacial periods, where they have been found in the profiles. The North African desert belt can be said to have expanded during Glacial times both towards the north and towards the south. All the available evidence of this study indicates that the grassland or the semi-deserts of Southern Europe came into connection with those of N Africa; there could not have been any forest zone between them. The present study was also a good opportunity for investigating some of the basic marine palynological problems. The very well known overrepresentation of pollen grains of the genus Pinus in marine sediments can be traced as far as 21° N. The present southern limit for the genus Pinus is on the Canaries and on the African continent at approximately 31° N. Highest values of Ephedra pollen grains even occur south of the main area of the present distribution of that genus. There does not seem to be any satisfactory explanation for this. In general, it would appear that the transport of pollen grains from the north is more important than transport from the south. The results so far, indicate strongly that further palynological studies are necessary. These should concentrate particularly on cores from between 33° N and 27° N as well as between 17° N and 10° N. It would also be useful to have a more detailed examination of sediments from the last Interglacial period (substage 5 e). Absolute pollen counts and a more general examination of surface samples would be desirable. Surface samples should be taken from the shelf down to the bottom of the continental slope in different latitudes.

Description: 33 species of polychaetes were collected, 27 of them were determined to species level. The majority of the species are cosmopolitans. Pulliella armata FAUVEL was found the first time in the Atlantic Ocean off Northwest Africa.

Description: The new Harpacticoidea genus Thieliella nov. gen. of the family Ancorabolidae SARS sensu LANG, 1909 with two new species from 500 m depth of the Island-Faroer-Ridge is described and discussed: Thieliella nordatlantica nov. spec. and Th. reducta nov. spec.

Description: 80 species of polychaetes were collected, 76 of them were determined to species level. One species (Harmothoe [Austrolaenilla] meteorae n. sp.) was described as new species. The majority of the species including the species of the cruises 26 and 44 are cosmopolitans (18%); 16% are distributed in cool temperate to tropical zones, 12.5% have their distribution in the eastern Atlantic and the Mediterranean, and 11% are distributed in tropical-subtropical to warm temperate zones.

Description: Nine species of Flustridae were collected by the R.V. "Meteor" in one subantarctic and three antarctic stations. Two new genera (Austroflustra and Neoflustra) and three new species (Austroflustra gerlachi, A. australis and Neoflustra dimorphica) are described. The diagnosis of the family is emended to include species with adventitious avicularia. Nematoflustra bifoliata D'HONDT and Flustra thysanica MOYANO are placed in the genus Securiflustra SILEN, and Flustra vulgaris KLUGE is transfered to Austroflustra.

Description: The species Stenhelia (Delavalia) noodti n. sp., Stenhelia (Delavalia) islandica n. sp., Pseudomesochra scheibeli n. sp. and Ameira faroerensis n. sp. are described from 500 m depth on the Island-Faroer-Ridge. Of special interest is Stenhelia (Delavalia) noodti n. sp. showing a reduction of the Exp A2 to one segment, a character described for this genus for the first time.

Description: Tracking a balloon with a single ship-based theodolite, is a method which has been used for a long time to determine the wind profile over the sea. There are two main sources of error: (a) the incorrect estimate of the height of the balloon and (b) the pitch and roll motions of the ship. In this paper the effects of both errors are investigated. The ship's motion is simulated with use of a transformation from a fixed (earth) to a moving (ship) coordinate system. Some examples are presented to illustrate the magnitude of these effects.

Description: During the 1971 "Meteor" survey of the Mediterranean Outflow, seven current meter moorings were deployed and several hydrographic stations executed. The time series data from almost all the current meters revealed a solitary increase in temperature with an amplitude of ≃ 1 °C and a duration of 2-4 days. The present analysis of the event shows that it was due to a thickening of the Mediterranean Outflow and an increase in the volume transport. The origin of the event is traced to the source of the Outflow from where it propagated with a speed of 16 cm s-1. Coinciding with the time at which the event passed the Strait of Gibraltar, the cross channel water level difference revealed an anomalous variation of about 8-cm amplitude and 3-day duration. Through conversion the magnitude of this fluctuation is now shown to simply a significant increase in the Outflow volume transport. An investigation of the reigning meteorological conditions indicates that, simultaneously, an impulse of water in the Alboran Sea was transported westwards by the wind. Through a qualitative and quantitative approach, the atmospheric forcing of the Western Mediterranean is thus linked to a large variation in the Outflow structure.

Description: On a cruise from the eastern into the western Mediterranean Sea in November/December 1978 a total of 126 samples were collected from 8 vertical profiles and 7 coastal stations for trace metal analysis. The sampling, processing and analysis was performed under strict "clean room" conditions. The concentration of the open-sea samples are close to oceanic results gathered under similar conditions. The grand averages from all profiles ( ± st. dev. of the individual samples) of 0.40 ± 0.16 µg l-1 Zn, 17.4 ± 7.4 ng l-1 Cd, 0.21 ± 0.07 µg l-1 Cu, 0.21 ± 0.13 µg l-1 Mn and 0.25 ± 0.09 μg l-1 Fe indicate that a "metal problem" does not exist in the open Mediterranean. A biologically mediated depletion in surface waters or correlation with nutrients have not been observed under the conditions established on this cruise. This is probably due to low primary production and seasonal advection processes prevailing in this sea. The data for manganese show generally higher values in the surface layer (0-75 m) than in deep waters. This could evidently proved in the nearshore profile indicating a terrigenous source for manganese.

Description: In general the natural aerosol reacts very sensitively to the change of relative humidity. This behaviour could be observed from August to September during the Atlantic "Meteor" -Expedition 1965, but not during the periods January to May 1969 and July to August 1974. There are some reasons for the assumption that this is an effect of organic material in the surfaces of the particles. But we do not know if this is an effect of different seasons or of increasing pollution of the atmospheric aerosol.

Description: Five reflection seismic profiles from the borderland between Messina Abyssal Plain and Malta Ridge (= Medina Rise), recorded during "Meteor" cruise no. 50 in 1978, are described. The subbottom/bottom structures are interpreted as a pattern of broad grabens and intercalated SW-NE striking narrow horsts. Within the grabens great thicknesses of Messinian evaporites as well as of Quaternary turbiditic sediments, depending on the respective differential sinking, were accumulated. Some of the horsts rise above the surrounding seafloor. Ontop of the horsts, being mainly composed of pre-Messinian series, only little or no evaporites at all were deposited. The cover of Quaternary sediments depends on the position of the horst with respect to the seafloor. The thickness of Pliocene sediments is constant within the whole studied area. The authors conclude from the observations that the pattern of horsts and grabens acted already during Messinian time producing the variable thickness of the evaporite layer. The relative movements between grabens and horsts as well as a general sinking of the whole area must have acted also in Pliocene and Quaternary time.

Description: Three sediment cores from the continental shelf and slope off NW Africa (Banc d'Arguin; 52 m, 665 m, and 973 m water depth) have been investigated by means of a coarse fraction analysis. The two shallower cores have been deposited during less than 10,000 years, the deeper one during the last 36,000 years. The Holocene sedimentation (〈 4000 years) in the deeper part of core 79 from the edge of the Banc d'Arguin is strongly influenced by reworking of Late Glacial dune sands and biogenic particles from shallower water (〈 40 m), as well as eroding current influence. A decrease in grain size of silicate material and a decrease in lateral supply, correlated to a doubling of accumulation rates in the upper part of the core, indicates a more autochthonous sedimentation with less sorting influence in the youngest Holocene. In core 86 from 665 m water depth a turbidite consisting mainly of silicate sand and silt separates two layers of autochthonous Holocene sediments. This turbidite shows a complete bioturbational mixing, only at its bottom the original bedding can be detected. Gradational changes in sediment composition indicate the decreasing admixture of allochthonous material from the bottom of the turbidite in 300 cm to about 140 (100) cm core depth. The depth of provenance of the allochthonous material can be assumed in 100-300 m water depth as indicated by various biogenous particles. Small amounts of shallow water particles in the autochthonous layers indicate a supply from shallow water, which probably occurred by the mechanism of "particle by particle supply". None of the three cores indicates upwelling influence, although oceanographers found intense upwelling in the area of the Banc d'Arguin. The Holocene climate in that area probably has been arid, small variations in terrigenous matter composition and grain size in the Early Holocene might be due to decreased wind strength or to an increase in rain fall. The Peak Glacial section (14,000-22,000 y.B.P.) of the deepest core 88 indicates a very much intensified eolian silt supply and an additional bottom supply of quartz sand. In the interval 22,000-36,000 y.B.P. wind strength decreased, but probably no increase in humidity occurred. So this area in about 19° 40' N had an arid climate in the Late Holocene and in the Peak Glacial. The fragmentation of planktonic foraminifers and the abundance of aragonitic tests of pteropods in core 88 indicate an Early Holocene (8330 y.B.P.) preservation spike. Two minima in fragmentation correlated to maxima in pteropod content at about 15,700 and 21,000 y.B.P. are correlated to maxima in shallow water supply and thus do not reflect preservation conditions, but only lateral supply from the carbonate dissolution minimum zone in about 300 m water depth.

Description: 86 sediment cores retrieved from water depths greater than 500 m off NW Africa between 12° and 28° N, were investigated by means of X-ray radiographs. Biogenic sedimentary structures occupy more than 90% of the examined area of sediment sections with the remaining 2% being turbidites and 8% slump masses. More than 20 types of lebensspuren can be distinguished. Most of them correspond to ichnogenera known from the fossil record: Chondrites, Corophioides, Helminthopsis, Lophoctenium, Planolites, Scolicia, Skolithos) Teichichnus) Thalassinoides) Trichichnus and Zoophycos. The observations are "uniformitarian" with respect to the lebensspuren encountered. Nevertheless, fossil counterparts to our sediments are not known, because (i) similar sedimentation processes at present are restricted to small areas, (ii) all of them are situated on passive continental margins, which are rarely preserved in the fossil record, and (iii) biogenic structures in silty marlstones are normally not very conspicuous in the fossil state. The sediments are highly bioturbated; in most cases biogenic reworking occurs repeatedly. The behaviour of the infaunal organisms and thus the formation of lebensspuren depends from the nutrient supply: In sediments with Corg greater than 2% only biodeformational structures are observed, while with Corg lower than 2% lebensspuren predominate. The lebensspuren inventory was found to be systematically arranged in a number of "bioturbation levels" below the sediment surface. With increasing sediment depth, a higher specialisation in the behaviour of the fauna is observed. Moreover, in each group of lebensspuren, the diameter decreases. The following levels are established: i. Level with biologically homogenized sediment, ii. Scolicia level (tubes, 2-4 cm diameter), iii. Planolites level tubes, 1 cm diameter), iv. level with small burrows of Chondrites) Helminthopsis (tube systems, 1-3 mm diameter) and spreiten burrows of Corophioides) Lophoctenium) and Teichichnus, v. Zoophycos level (spreiten burrows). With increasing water depth, the thickness of the bioturbated sediment decreases from 80 cm at 500 m to 40-60 cm at 2000 m and 15-25 cm at 4750 m. Based on the levels, biogenic sedimentary structures are grouped into "associations" having ecological significance. The following associations are established: (1) biodeformational association dominating in sediments with Corg greater than 2% ; (2) Scolicia association, (3) Planolites association [(2) and (3) depend on the sediment grain size: (2) in sediments with high content of silicate particles 〉 20 μm, (3) in sediments with clay content 〉 50%] ; ( 4) Vertical spreiten association, (5) Chondrites association, (6) Zoophycos association [( 4) through ( 6) predominate in glacial sediments, (4) in water depth about 1000 m, (5) below 1000 m, and (6) between 2000 and 4000 m]. The formation of different biogenic sedimentary structures and thus the distribution of lebensspuren associations depends on the environmental conditions. Generally, the diversity of lebensspuren is higher in glacial than interglacial sediments. This phenomenon is attributed to a higher rate of Corg accumulation and preservation in glacial sediments, possibly because of changes in the circulation of water masses. The sediments become mixed in different style by different lebensspuren types. Because biogenic reworking is - as a rule - repeated several times, the vertical mixing effect is considerable, though difficult to estimate. Stratigraphic resolution is optimal in core sections with Scolicia, where vertical mixing is restricted. Here stratigraphic resolution reaches an accuracy of about 200-300 years where the sedimentation rate is 10-20 cm/1000 years.

Description: The terrigenous sediment proportion of the deep-sea sediments from off Northwest Africa has been studied in order to distinguish between the aeolian and the fluvial sediment supply. The present and fossil Saharan dust trajectories were recognized from the distribution patterns of the aeolian sediment. The following time slices have been investigated: Present, 6,000, 12,000 and 18,000 y.B.P. Futhermore, the quantity of dust deposited off the Saharan coast has been estimated. For this purpose, 80 surface sediment samples and 34 sediment cores have been analysed. The stratigraphy of the cores has been achieved from oxygen isotopic curves, 14 C-dating, foraminiferal transfer temperatures, and carbonate contents. Silt sized biogenic opal generally accounts for less than 2% of the total insoluble sediment proportion. Only under productive upwelling waters and off river mouths, the opal proportion exceeds 2% significantly. The modern terrigenous sediment from off the Saharan coast is generally characterized by intensely stained quartz grains. They indicate an origin from southern Saharan and Sahelian laterites, and a zonal aeolian transport in midtropospheric levels, between 1.5 and 5.5 km, by "Harmattan" Winds. The dust particles follow large outbreaks of Saharan air across the African coast between 15° and 21° N. Their trajectories are centered at about 18° N and continue further into a clockwise gyre situated south of the Canary Islands. This course is indicated by a sickle-shaped tongue of coarser grain sizes in the deep-sea sediment. Such loess-sized terrigenous particles only settle within a zone extending to 700 km offshore. Fine silt and clay sized particles, with grain sizes smaller than 10-15 μm, drift still further west and can be traced up to more than 4,000 km distance from their source areas. Additional terrigenous silt which is poor in stained quartz occurs within a narrow zone off the western Sahara between 20° and 27° N only. It depicts the present dust supply by the trade winds close to the surface. The dust load originates from the northwestern Sahara, the Atlas Mountains and coastal areas, which contain a particularly low amount of stained quartz. The distribution pattern of these pale quartz sediments reveals a SSW-dispersal of dust being consistent with the present trade wind direction from the NNE. In comparison to the sediments from off the Sahara and the deeper subtropical Atlantic, the sediments off river mouths, in particular off the Senegal river, are characterized by an additional input of fine grained terrigenous particles (〈 6 μm). This is due to fluvial suspension load. The fluvial discharge leads to a relative excess of fine grained particles and is observed in a correlation diagram of the modal grain sizes of terrigenous silt with the proportion of fine fraction (〈 6 μm). The aeolian sediment contribution by the Harmattan Winds strongly decreased during the Climatic Optimum at 6,000 y.B.P. The dust discharge of the trade winds is hardly detectable in the deep-sea sediments. This probably indicates a weakened atmospheric circulation. In contrast, the fluvial sediment supply reached a maximum, and can be traced to beyond Cape Blanc. Thus, the Saharan climate was more humid at 6,000 y.B.P. A latitudinal shift of the Harmattan driven dust outbreaks cannot be observed. Also during the Glacial, 18,000 y.B.P., Harmattan dust transport crossed the African coast at latitudes of 15°-20° N. Its sediment load increased intensively, and markedly coarser grains spread further into the Atlantic Ocean. An expanded zone of pale-quartz sediments indicates an enhanced dust supply by the trade winds blowing from the NE. No synglacial fluvial sediment contribution can be recognized between 12° and 30° N. This indicates a dry glacial climate and a strengthened atmospheric circulation over the Sahelian and Saharan region. The climatic transition phase, at 12,000 y.B.P., between the last Glacial and the Interglacial, which is comparable to the Allernd in Europe, is characterized by an intermediate supply of terrigenous particles. The Harmattan dust transport was weaker than during the Glacial. The northeasterly trade winds were still intensive. River supply reached a first postglacial maximum seaward of the Senegal river mouth. This indicates increasing humidity over the southern Sahara and a weaker atmospheric circulation as compared to the Glacial. The accumulation rates of the terrigenous silt proportion (〉 6 μm) decrease exponentially with increasing distance from the Saharan coast. Those of the terrigenous fine fraction (〈 6 μm) follow the same trend and show almost similar gradients. Accordingly, also the terrigenous fine fraction is believed to result predominantly from aeolian transport. In the Atlantic deep-sea sediments, the annual terrigenous sediment accumulation has fluctuated, from about 60 million tons p.a. during the Late Glacial (13,500-18,000 y.B.P., aeolian supply only) to about 33 million tons p.a. during the Holocene Climatic Optimum (6,000-9,000 y.B.P., mainly fluvial supply), when the river supply has reached a maximum, and to about 45 million tons p.a. during the last 4,000 years B.P. (fluvial supply only south of 18° N).

Description: A new technique for the harmonic analysis of current observations is described. lt consists in applying a linear band pass filter which separates the various species and removes the contribution of non-tidal effects at intertidal frequencies. The tidal constituents are then evaluated through the method of least squares. In spite of the narrowness of the fitter, only three days of data are lost through the filtering procedure and the only requirement on the data is that the time interval between samples be an integer fraction of one day. This technique is illustrated through the analysis of a few French current observations from the English Channel within the framework of INOUT. The characteristics of the main tidal constituents are given.

Description: 14C concentrations, as weil as 13C, hydrographic and nutrient data are reported for 5 hydrographic stations that form a transatlantic section near 40° N ("Meteor" cruise no. 23, 1971). Precision (for 14C ± 0.3% or better) and comparability with literature data are specified. A planned intercomparison with the US GEOSECS program within the Newfoundland Basin deep water failed because of variability of water characteristics. The observed 14C values decrease from about Δ 14C = + 80‰ at the surface to -70‰ at 2000 m depth. Deeper down, the values west of the Midatlantic Ridge remain similar, whereas those east of the ridge decrease further, to about -110‰. It is shown that bomb-14C is prominent down to about 1500 m depth. Beyond this depth the bomb 14C component is small and is negligible in the eastern basin below 2800 m. On the basis of the 14C-tritium correlation, the distribution of natural 14C below about 1500 m depth is derived from the observations. In the deep and bottom water east of the ridge the 14C-salinity relationship seemingly is non-linear. Contrary to expectation, the 14C concentration in the bottom water is not lower than found on an US GEOSECS station near 10° N. Apparently, lateral concentration differences in the Northeast Atlantic bottom water as well as nonlinearity of the 14C-salinity relationship at 40°N do not exceed 10‰ in Δ 14C.

Description: The grazing of different copepodite stages of Calanus finmarchicus on natural phytoplankton populations was measured at different times of day and night during the Fladen Ground Experiment (FLEX), from the end of May to the beginning of June 1976, at the central position of the "FLEX box" (58° 55' 00" N, 0° 32' 05" E), on board of the R.V. "Meteor". A big difference between nocturnal and diurnal food intake was found, particularly for the stages V & IV, which at night ingest 4 to 10 times more than during daytime. The maximal daily food intake (24 hours), taking into account the different feeding rates at the different times of the day and expressed as percent of own carbon weight, was found to be 31 %, 83 %, 115 % and 148 % for the copepodite stages V, IV, III, II and I together, respectively, with an initial feeding threshold at about 50-60 µg C · l-1. The total grazing for the upper 40 m depth layer was calculated for each sampling time; a very pronounced grazing rhythm was found, due to the higher ingestion rates at night combined with the vertical migrations. Maximal night ingestions were 100-200 mg C/m2/hour at the end of May to 300-400 mg C/m2/hour at the beginning of June, compared with 1-20 mg C/m2/hour at midday. Making a balance of the positive influence of particulate primary production and the negative influence of grazing on the stock of particulate carbon, we could show that the main cause of the decline of the phytoplankton bloom in this period was Calanus grazing. Other zooplankton activities, namely respiration, production and faecal pellets excretion as measured by four other authors are in balance with our results of ingestion.

Description: "Auftrieb 75" was a joint cruise of R.V. "Meteor" and R.R.S. "Discovery" performed in the area 21-26° N off the northwest African coast during January-March, 1975. Current meter observations from six moorings and CTD/STD observations from three repeatedly covered sections of the cruise are analysed in order to describe the distribution of the water masses and its variability with the changes in the current system. The Canary Current is seen to pass through the northwestern corner of the expedition area, carrying with it a geostrophic eddy with a period in excess of 30 days. The eddy is probably another example of the type generally found in the open ocean circulation. Further south, offshore currents display large variations in strength and direction with a typical time scale of 10-14 days which are believed to reflect largescale mixing processes along the boundary of the Canary Current and the poleward flow of the coastal region, involving North Atlantic Central Water (NACW) and South Atlantic Central Water (SACW). The coastal upwelling undercurrent has been observed along the shelf edge but undergoes large variations in response to the wind and to variations in the horizontal divergence of the offshore currents. On the shelf the circulation responds to the local longshore wind to some extent but is also strongly affected by variations of the currents at the shelf edge. The distribution of water masses at intermediate depth ( 100-800 m) is analysed quantitatively based on the assumption that mixing between NACW and SACW is effective along surfaces of constant density only. lt is shown that most intense mixing occurs at about 22-23° N and is still very important further south. At 25-26° N SACW has been absorbed into the surrounding NACW water mass to a high degree, even in the undercurrent. Isolated bodies of water are found in the southern part of the expedition area, some of which are carried north in the undercurrent. The large variability in the water mass distribution at the source level of the upwelling probably has important consequences for the variations in the efficiency of biological production of the upwelling region.

Description: The main objectives of the Fladen Ground Experiment (FLEX) 1976 were an investigation of the dynamics of the mixed layer and the development of the spring plankton bloom. A quantitative consideration of individual chemical parameters (nutrients, particulate nitrogen and phosphorus) showed it to be advantageous to divide the water column into several layers which are separated from one another by measured temperature gradients. Measurements of particulate matter (phosphorus and nitrogen) revealed two plankton blooms at the central station. The first one (21.4.-14.5.76) was much more extensive than the second one, since the limiting thermocline was at a depth of about 60 m. Silicate was consumed most rapidly during this bloom and almost completely exhausted. The second bloom (19.-30.5.76) produced concentrations of particulate matter which were almost as high as the first one but were limited in only a few meters' water depth by a secondary thermocline, which prevented an influx of nutrients. Nitrate was completely exhausted during the second bloom. A high degree of nutrient depletion in the mixed layer from 24.4.-29.4. and from 22.5.-27.5.76 make these periods appear well-suited for determination of uptake rates. These periods are characterized. by a parallel course of concentration curves in the upper water layers for all nutrients except ammonium, and by the absence of !arge short-term fluctuations. Thus, disturbances due to hydrodynamic effects were minimal. The effects of tidal changes were minimized by using daily averages of the various concentrations. However, from 9.5.-13.5.7 6 in the upper layer a relatively strong and rapid increase was observed in the concentrations of all nutrients, which can probably only be explained by hydrodynamic influences. The nitrogen and phosphorus budgets can only be approximately balanced without considering dissolved organic matter. The strong decrease in dissolved inorganic nutrients during the first plankton bloom is almost comple,tely compensated by the increase in particulate matter. Not considering hydrodynamic influences, deficits after the plankton bloom could be explained by the fact that dissolved organic substances, as weil as sedimentaty matter and zooplankton, either were not considered at all, or at least not quantitatively. The time periods from 2.-7.4. and from 21.4.-14.5.76 show no strong short-term fluctuations in the nitrogen and phosphorus budgets and appear most suitable for calculations of mass fluxes, uptake and production rates, since biological-chemical processes seem to be dominant over hydrodynamic ones during these periods.

Description: The monthly mean meteorologically induced circulation of the North Sea for the period 15 March to 15 April 1976 (JONSDAP '76 INOUT period) is computed using two numerical models. One has a fine grid resolution, is two-dimensional, comprehensively non-linear and covers the North Sea. The other has a coarser grid resolution, is three-dimensional, and linear except for the inclusion of quadratic bottom friction. The depth variation of the two horizontal components of current in this model is accomplished using an expansion of time and horizontally dependent coefficients and depth dependent functions. The three-dimensional modelling technique presented here is sufficiently flexible to allow an arbitraty space and time variation of vertical eddy viscosity, although still retaining a continuous representation of current in the vertical, and allowing for variable bottom topography. Preliminary results presented here for the meteorologically induced circulation of the North Sea during JONSDAP '76 agree weil with present knowledge of the circulation of the North Sea. Comparing surface and bottom currents computed with the 3 D shelf model, it is evident that the windinduced flow varies considerably in both magnitude and direction between sea surface and sea bottom. The distribution of depth mean current computed with the 3 D shelf model over the North Sea is nearly identical to that computed with the 2 D North Sea model. This is particularly encouraging since the 3 D shelf model does not contain the advective terms, which are present in the 2 D model, and has a coarser resolution.

Description: The ecology of the lower marine fungi, namely the thraustochytrids, in the Fladen Ground area (FLEX box) and other parts of the North Sea was studied during 5 cruises in 1975 and 1976. The number of fungi/liter and the number of species showed seasonal fluctuations in the surface water samples from all the stations. A high number was found in September 1976 and a low number in March 1976. These numbers, however, revealed no seasonal fluctuations in the underlying sediments. In both the surface waters and the sediments, a consistently low number of fungi was recorded for certain stations and a high number of fungi for others, the reason for this being unknown. The sediments revealed a very high number of fungi/liter. Observations on the distribution of various species are presented. Certain species occurred more frequently at some stations than at others; certain species occurred more in the water column, e. g. Ulkenia minuta, and still others in the sediments, e. g. Thraustochytrium multirudimentale.

Description: In the framework of the Fladen Ground Experiment 1976, zooplankton samples were taken during the phytoplankton spring bloom in April-May and after the bloom in June. The plankton was collected with two samplers, a towed multiple high-speed sampler and a newly developed swing net for local sampling. The results of both methods are compared. The mean number and dry weight per m3 are given for the common species, as weil as the density of fecal pellets. The calanoid copepod Calanus finmarchicus formed 63 %, resp. 90 % of the biomass. The population composition, distribution, dry weight/length relationship and productivity of this species is studied in more detail. The high abundance of fecal pellets, eggs and young stages during the spring bloom indicate a high zooplankton activity in this period. The low density of these indicators and the apparent descent of the older Calanus stages to deep water layers in June signify the dependency of the zooplankton activity on the phytoplankton density. The estimated daily production of Calanus during the phytoplankton bloom was 20 mgC/m2. The significance of the seasonal vertical migration and the role of zooplankton in the northern North Sea ecosystem is discussed. lt is concluded that the Zooplankton could have checked the low algal density in May-June after the spring bloom, but it is far from certain that it stopped the phytoplankton outburst at the end of April and early May.

Description: During the culmination of the phytoplankton spring bloom in the Fladen Ground area in April-Mai 1976, gross primary production was between 1500 and 2000 mg particulate C m-2 day-1, at a crop density (mainly diatoms of the genus Chaetoceros) of about 1500-3500 mg C m-2. Estimates of the C : chlorophyll a ratio in living cells were much lower than those reported in the literature, possibly because part of what is measured as "chlorophyll a" by the common fluorometric method is associated with particles that are not reported as cells. Most of the dark 14C fixation during the bloom's climax was due to abiotic processes. Excretion of 14C-labeled carbohydrates did not account for a significant fraction of the total photosynthetic rate. The low crop after the bloom period, in June, corresponded with nutrient depletion of the euphotic zone. The low photosynthetic efficiency in June may have been a gross underestimate. The presence of relatively high concentrations of chlorophyll derivatives signifies that the algal crop was consumed by heterotrophs, but at a lower rate in April/May than during the June cruise when particularly high molar ratios of phaeophorbide a and phaeophytin a relative to chlorophyll a were found. The high respiratory rate relative to autotrophic production in June manifested itself also in high dark 14C fixation values. The high concentration of phaeophorbide a in the upper 40 m and its scarcity below this depth during the spring bloom climax in April/May implies that copepod grazing at that time took place principally in the euphotic zone. The remarkably high concentration of chlorophyllide a in the surface layer during the bloom period indicates that the part of the crop that was destroyed by the grazers while eating was occasionally as high as the part that was actually ingested.

Description: During the Fladen Ground Experiment (FLEX, March 26-June 6, 1976) quantitative investigations of herbivorous zooplankton were performed. For that purpose 1785 water samples (5 or 10 l) were taken with a rosette sampler at the central station (pos. 58° 55' N, 0° 32' E) from nine to ten standard depths and filtered through 30 µm gauze filters. The development of the most important Zooplankton groups at the central Station is presented in depth-integrated time series (0-100 m) of individuals per m2. The number of individuals of Calanus finmarchicus was converted to biomass (dry weight). At the end of the sampling at the central station the standing stock of Calanus finmarchicus showed about 18 g dry weight per m2. Numerical values for the time lags between different plankton groups are calculated with the aid of the cross-correlation function. The time lag between the diatom ad copepod egg peaks is only up to 2.75 days; that between diatoms and the larvae of bottom invertegrates is 5 days. Between the copepod eggs and the maximum number of nauplii (N I-N VI) there is a time lag of 10.75 days. Another 10.25 days lie between the maximum numbers of nauplii and copepodites (C I-C VI). Considering the depth-integrated time series of the abundance of Calanus finmarchicus copepodites, a succession of the Stages seems to exist. Nevertheless, numerical values for the time lags between the different developmental stages cannot be calculated unambiguously by the cross-correlation technique. This is probably caused by extreme simultaneous fluctuations, especially of the numbers of all stages of Calanus finmarchicus in the last phase of the sampling at the central station.

Description: The third phase of the cooperative data collection program JONSDAP begun in 1970 by the countries bordering on the North Sea was planned to include for the first time biological and chemical measurements in 1976, as well as physical ones. Intensive measurement programs were performed, one concentrating on the currents flowing into and out of the open boarders of the North Sea (INOUT) for 40 days in March/ April and one in which the dependence of the spring plankton bloom on the vertical temperature structure was studied in the Fladen Ground area for 100 days from March to June (FLEX). Around 90 % of the planned program with moored systems and 75 % of the measurements from moving ships were able to be carried out successfully. The large quantities of data required the establishment of two data centers. The current data were collected in Liege, all data from the FLEX box in Hamburg. A cooperative JONSDAP format was agreed on for the exchange of data. Graphic presentations of the data have been compiled in the two-volume Draft FLEX/IN OUT Atlas and distributed to all JONSDAP '76 participants, one of the main purposes of which being the facilitation of interdisciplinary evaluations, now that the intradisciplinary data processing has almost been completed - as presented in this volume.

Description: Measurements of nutrients and the elements phosphorus and nitrogen from the central station in FLEX '76 were used to calculate mass fluxes and budgets for these elements in defined time and depth intervals. The intervals were defined using hydrodynamic and biological criteria. Within these periods rates of increase and decrease were calculated for nitrate, ammonium, phosphate, particulate nitrogen and phosphorus. These rates were also calculated for the layer above and below the main thermocline. The element budget was balanced within some of the defined intervals. This was possible by only considering biological, chemical, and vertical physical interactions at the central station. At the beginning of the phytoplankton bloom we found fluxes with a maximum of 28 ngat · l-1 · d-1 for phosphorus and 590 ngat · l-1 · d-1 for nitrogen. Interaction diagrams are shown for mass fluxes for three periods during the plankton bloom.

Description: Since both German research vessels „Meteor" played a major role in G. Dietrich's work, it seemed appropriate to present his bibliography in this series. An assessment of his scientific achievements was given at an earlier date (H. U. ROLL 1973: In memoriam GüNTER DIETRICH 1911-1972. - ,,Meteor" Forsch.­ Ergebn. A, No. 12: V-X).

Description: Vertical velocity spectra can be determined by three different indirect methods: Following isopycnal surface displacements, following isothermal surface displacements, or calculating water particle displacements from temperature time series at fixed pressure levels, with the mean vertical temperature gradient used for the conversion factor. This third method is the easiest to perform. Data from GATE 1974, obtained by CTD profiling onboard R. V. "Meteor" and by temperature measurements on moorings, are used to check whether the three methods are equivalent. lt is shown that autospectra do not differ significantly within the 95 % confidence intervals, and either method can be applied. This does not infer an equivalence with respect to the actual data points since individual events were found in the low-passed time series with deviations occurring between displacement curves obtained by the different methods. These events were apparently due to the advection of another water mass.

Description: The research programmes of the German groups in JASIN 1978 are summarized, comprising projects that concern the planetary boundary layer, the radiation budget, the oceanic mixed layer and thermocline and the trace element exchange. Lists of the participating scientists and technicians are included. Brief descriptions of the field activities on board the three ships and the aircraft are given, including maps and stations lists.

Description: A first survey of the entire temperature data base from the central station is presented. The development and the changes of the sea surface temperature, the thermocline, and the heat content due to meteorological forces, are described.