Multibeam and seismic survey, physical oceanography, and sea-bottom videos from the Bay of Biscay

We report the northernmost and deepest known occurrence of deep-water pycnodontine oysters, based on two surveys along the French Atlantic continental margin to the La Chapelle continental slope (2006) and the Guilvinec Canyon (2008). The combined use of multibeam bathymetry, seismic profiling, CTD casts and a remotely operated vehicle (ROV) made it possible to describe the physical habitat and to assess the oceanographic control for the recently described species Neopycnodonte zibrowii. These oysters have been observed in vivo in depths from 540 to 846 m, colonizing overhanging banks or escarpments protruding from steep canyon flanks. Especially in the Bay of Biscay, such physical habitats may only be observed within canyons, where they are created by both long-term turbiditic and contouritic processes. Frequent observations of sand ripples on the seabed indicate the presence of a steady, but enhanced bottom current of about 40 cm/s. The occurrence of oysters also coincides with the interface between the Eastern North Atlantic Water and the Mediterranean Outflow Water. A combination of this water mass mixing, internal tide generation and a strong primary surface productivity may generate an enhanced nutrient flux, which is funnelled through the canyon. When the ideal environmental conditions are met, up to 100 individuals per m² may be observed. These deep-water oysters require a vertical habitat, which is often incompatible with the requirements of other sessile organisms, and are only sparsely distributed along the continental margins. The discovery of these giant oyster banks illustrates the rich biodiversity of deep-sea canyons and their underestimation as true ecosystem hotspots.

Digital terrain model (DTM) of the central Fram Strait

Based on data from R/V Polarstern multibeam sonar surveys between 1984 and 1997 a high resolution bathymetry has been generated for the central Fram Strait. The area ensonified covers approx. 36,500 sqkm between 78°N-80°N and 0°E-7.5°E. Basic outcome of the investigation is a Digital Terrain Model (DTM) with 100 m grid spacing which was utilized for contouring and generation of a new series of bathymetric charts (AWI BCFS).

Heimat - Studentisches Medienprojekt zur Internationalen REKLIM Konferenz in Kooperation mit der DEKRA-Hochschule Berlin, Links zum Viralfilm in unterschiedlichen Auflösungen

Eine scheinbar ganz normale Familie an einem ganz normalen Abend - bis der Sohn beginnt, die Wände mit Graffiti zu verzieren. Die Eltern fallen ein in einen Rausch der Verwüstung. Aber wie kann man nur sein eigenes Zuhause zerstören?

Mineral dust deposition in interglacial and glacial climate conditions: model results

The global aerosol/climate model ECHAM5-HAM is used in order to investigate the dust cycle for four interglacial and one glacial climate conditions. The 20-year time-slices are the pre-industrial control (CTRL), mid-Holocene (6000 years BP), last glacial inception (115000 years BP), Eemian (126000 years BP) and Last Glacial Maximum (LGM) (21000 years BP) time intervals. The study is focused on the Antarctic region. The model is able to reproduce the magnitude order of dust deposition globally for the pre-industial and LGM climates. Correlation coefficient of the natural logarithm of the observed and modeled values is 0.78 for the CTRL and 0.81 for the LGM. For the pre-industrial simulation the model overestimates observed values in Antarctica by a factor of about 2-3 due to overestimation of the Australian dust source and too high wet deposition in the Antarctica interior. In the LGM, the model underestimates dust deposition in eastern Antarctica by a factor of about 4-5 due to underestimation of the South American dust source. More records are needed to validate dust deposition for the past interglacial time-slices. The modeled results show that dust deposition in Antarctica in the past interglacial time-slices is higher than in the CTRL simulation. The largest increase of dust deposition in Antarctica is simulated for the LGM, showing about 10-fold increase compared to CTRL.

A laboratory-scale experiment and a numerical simulation of unusual spiral plumes in a High-Prandtl-number fluid, links supplementary material

We experimentally and numerically investigated the generation of plumes from a local heat source (LHS) and studied the interaction of these plumes with cellular convective motion (CCM) in a rectangular cavity filled with silicon oil at a Prandtl number (Pr) of approximately two thousand. The LHS is generated using a 0.2-W green laser beam. A roll-type CCM is generated by vertically heating one side of the cavity. The CCM may lead to the formation of an unusual spiral convective plume that resembles a vertical Archimedes spiral. A similar plume is obtained in a direct numerical simulation. We discuss the physical mechanism for the formation of a spiral plume and the application of the results to mantle convection problems. We also estimate the Reynolds (Re) and Rayleigh (Ra) numbers and apply self-similarity theory to convection in the Earth's mantle. Spiral plumes can be used to interpret mantle tomography results over the last decade.

Studentisches Medienprojekt zur Internationalen REKLIM Konferenz in Kooperation mit der DEKRA-Hochschule Berlin

Ein interdisziplinäres und interaktives Medienprojekt von und für junge Menschen zum Thema "Regionale Klimaänderungen". Der Klimawandel ist eines der wichtigsten Zukunftsthemen und Handlungsfelder unserer Zivilgesellschaft, mit weltweiter Relevanz und regionalen Auswirkungen. Die jungen Menschen heute sind diejenigen, die in Zukunft von den Folgen der Klimaveränderungen besonders stark betroffen sein werden. Sie sind aber auch gleichzeitig gefordert zu erkennen, dass wir andere Lebensstile finden und Vermeidungs- und Anpassungsstrategien jetzt auf den Weg bringen müssen, da diese Maßnahmen nur sehr langfristig wirken. Es liegt noch zu wenig im Erfahrungs- und Erlebenshorizont vieler junger Menschen, Maßnahmen zu Klimaschutz und -anpassung als wichtige Bausteine für die eigene Zukunft zu begreifen und aktiv als Thema anzunehmen. Daher bedarf es einer frühen und intensiven Auseinandersetzung mit dieser gesellschaftlichen Herausforderung als Teil der eigenen Lebenswirklichkeit. Zielgruppe des Medienprojektes war hier die heranwachsende Generation im Ausbildungsalter (16-30 Jahre). Die Helmholtz-Klimainitiative REKLIM (Regionale Klimaänderungen) und die DEKRA Hochschule Berlin haben sich 2013 gemeinsam auf den Weg gemacht, den Prozess der Auseinandersetzung und der Bewusstseinsbildung für die Bedeutung dieses Themas für junge Menschen in einem gemeinsamen interdisziplinären Projekt anzustoßen (www.reklim-medienprojekt.de). Gewählt für die Umsetzung dieses Projektes wurde die internationale REKLIM Konferenz "Our Climate - Our Future, Regional Perspectives on a global Challenge", die vom 6. - 9. Oktober 2014 in Berlin stattfand. Das ins Leben gerufene Medienprojekt zu dieser wissenschaftlichen Konferenz vereinte die Expertisen beider Projektpartner, um das Thema "Regionale Klimaänderungen" von jungen Menschen für junge Menschen zu adressieren und sie in ihrer eigenen Sprache und Mediennutzung zu erreichen. Insgesamt konnten mehr als 80 Studierende aus den Studiengängen Fernsehen und Film, Journalismus und Medienmanagement der DEKRA Hochschule Berlin in diesem einzigartigen Projekt in die Wissenschaftskonferenz eingebunden werden. Mit selbst konzipierten und produzierten Medienprodukten (u.a. einem Blog, mehreren Dokumentarfilmen, Viralen Videos sowie täglichen Berichterstattungen) für die Öffentlichkeit sollten die regionalen Aspekte des Klimawandels, die in der Helmholtz-Klimainitiative REKLIM wissenschaftlich erarbeitet werden, der Öffentlichkeit zugänglich gemacht werden. Den Studierenden kam dabei die wichtige Rolle zu, die wissenschaftlichen Inhalte in eine filmkünstlerische, journalistische und junge Sprache zu transformieren, mit unvoreingenommener Perspektive auf die Probleme zu schauen und die Wissenschaftlerinnen und Wissenschaftler dabei gleichsam mit einzubinden. So ist in dem Projekt ein wichtiger Dialog- und Lernprozess zwischen den verschiedenen Disziplinen entstanden. Darüber hinaus bot die Zusammenarbeit für die Wissenschaftlerinnen und Wissenschaftler des REKLIM-Verbunds und der beteiligten Zentren eine einmalige Chance, eine mediale Öffentlichkeit herzustellen, die es in dieser Form vermutlich für eine derartige Konferenz noch nicht gegeben hat. Für die Studierenden der DEKRA Hochschule bedeutete das Medienprojekt wichtige Erfahrungen in der projektbezogenen Arbeit mit einem externen Partner zu einem gesellschaftsrelevanten Thema zu sammeln. Das REKLIM-Medienprojekt verfolgt die Ziele: - in einem interdisziplinären und interaktiven Projekt junge Menschen zur Auseinandersetzung mit dem Klimawandel und zur Bewusstseinsbildung für die Bedeutung der regionalen Klimaänderungen anzuregen, - durch die von den Studierenden entwickelten Medienprodukte eine Verbindung zwischen den wissenschaftlichen Arbeiten und einer breiten Öffentlichkeit zu ermöglichen, - einen Dialogprozess zwischen Wissenschaftler/-innen und Studierenden zu initiieren, - wissenschaftliche Inhalte über künstlerische und mediale Transferprozesse anschaulich und ansprechend einer breiten Öffentlichkeit, insbesondere jungen Menschen, näherzubringen, um sie für das Thema Klimawandel und seine regionalen Auswirkungen zu sensibilisieren, - einen Dialog- und Lernprozess zwischen den verschiedenen Disziplinen anzuregen.

Planimetric ice-flow convergence and flow-orthonormal strain rate across the Antarctic Ice Sheet, with links to model result files

Fast-flowing ice streams discharge most of the ice from the interior of the Antarctic Ice Sheet coastward. Understanding how their tributary organisation is governed and evolves is essential for developing reliable models of the ice sheet's response to climate change. Despite much research on ice-stream mechanics, this problem is unsolved, because the complexity of flow within and across the tributary networks has hardly been interrogated. Here I present the first map of planimetric flow convergence across the ice sheet, calculated from satellite measurements of ice surface velocity, and use it to explore this complexity. The convergence map of Antarctica elucidates how ice-stream tributaries draw ice from the interior. It also reveals curvilinear zones of convergence along lateral shear margins of streaming, and abundant convergence ripples associated with nonlinear ice rheology and changes in bed topography and friction. Flow convergence on ice-stream tributaries and their feeding zones is markedly uneven, and interspersed with divergence at distances of the order of kilometres. For individual drainage basins as well as the ice sheet as a whole, the range of convergence and divergence decreases systematically with flow speed, implying that fast flow cannot converge or diverge as much as slow flow. I therefore deduce that flow in ice-stream networks is subject to mechanical regulation that limits flow-orthonormal strain rates. These properties and the gridded data of convergence and flow-orthonormal strain rate in this archive provide targets for ice- sheet simulations and motivate more research into the origin and dynamics of tributarization.

Gas emissions and ROV survey tracks of the Regab pockmark (Northern Congo Fan)

Pockmarks are seafloor depressions commonly associated with fluid escape from the seabed and are believed to contribute noticeably to the transfer of methane into the ocean and ultimately into the atmosphere. They occur in many different areas and geological contexts, and vary greatly in size and shape. Nevertheless, the mechanisms of pockmark growth are still largely unclear. Still, seabed methane emissions contribute to the global carbon budget, and understanding such processes is critical to constrain future quantifications of seabed methane release at local and global scales. The giant Regab pockmark (9°42.6' E, 5°47.8' S), located at 3160 m water depth near the Congo deep-sea channel (offshore southwestern Africa), was investigated with state-of-the-art mapping devices mounted on IFREMER's (French Research Institute for Exploitation of the Sea) remotely operated vehicle (ROV) Victor 6000. ROV-borne micro-bathymetry and backscatter data of the entire structure, a high-resolution photo-mosaic covering 105,000 m2 of the most active area, sidescan mapping of gas emissions, and maps of faunal distribution as well as of carbonate crust occurrence are combined to provide an unprecedented detailed view of a giant pockmark. All data sets suggest that the pockmark is composed of two very distinctive zones in terms of seepage intensity. We postulate that these zones are the surface expression of two fluid flow regimes in the subsurface: focused flow through a fractured medium and diffuse flow through a porous medium. We conclude that the growth of giant pockmarks is controlled by self-sealing processes and lateral spreading of rising fluids. In particular, partial redirection of fluids through fractures in the sediments can drive the pockmark growth in preferential directions.

The CLIMATE data base of monthly normals for globally gridded climatic variables (version 2.1)

This database (Leemans & Cramer 1991) contains monthly averages of mean temperature, temperature range, precipitation, rain days and sunshine hours for the terrestrial surface of the globe, gridded at 0.5 degree longitude/latitude resolution. All grd-files contain the same 62483 pixels in the same order, with 30' latitude and longitude resolution. The coordinates are in degree-decimals and indicate the SW corner of each pixel. Topography is from ETOPO5 and indicates modal elevation. Data were generated from a large data base, using the partial thin-plate splining algorithm (Hutchinson & Bischof 1983). This version is widely used around the globe, notably by all groups participating in the IGBP NPP model intercomparison.

Static GPS measurements in the vicinity of EDML and an elevation model for Dronning Maud Land

The knowledge of ice sheet surface topography and the location of the ice divides are essential for ice dynamic modeling. An improved digital elevation model (DEM) of Dronning Maud Land (DML), Antarctica, is presented in this paper. It is based on ground-based kinematic GPS profiles, airborne radar altimetry, and data of the airborne radio-echo sounding system, as well as spaceborne laser altimetry from NASA's Ice, Cloud and land Elevation Satellite (ICESat). The accuracy of ICESat ice sheet altimetry data in the area of investigation is discussed. The location of the ice divides is derived from aspect calculation of the topography and is verified with several velocity data derived from repeated static GPS measurements.

Magnetic anomaly map of the Weddell Sea Region, Antarctic (Scale 1:2 500 000)

This paper describes a 1 : 2 500 000 scale aeromagnetic anomaly map produced by the joint efforts of VNIIOkeangeologia, Polar Marine Geological Research Expedition (PMGRE) and the Alfred Wegener Institute for Polar and Marine Research (AWl) for the Weddell Sea region covering 1 850 000 km' of West Antarctica. Extensive regional magnetic survey flights with line-spacing of about 20 km and 5 km were carried out by the PMGRE between 1977 and 1989. In course of these investigations the PMGRE flew 9 surveys with flight-line spacing of 20 km and 6 surveys with flight-line spacing of 5 km mainly over the mountain areas of southern Palmer Land, western Dronning Maud Land, Coats Land and Pensacola Mountains, over the Ronne lee Shelf and the Filchner Ice Shelf and the central part of the Weddell Sea. More than 215 000 line-kilometers of total field aeromagnetic data have been acquired by using an Ilyushin Il-14 ski-equipped aircraft. Survey operations were centered on the field base stations Druzhnaya-1, -2, and -3, from which the majority of the Weddell Sea region network was completed. The composite map of the Weddell Sea region is prepared in colour, showing magnetic anomaly contours at intervals of 50-100 nT with supplemental contours at an interval of 25 nT in low gradient areas, on a polar stereographic projection. The compiled colour magnetic anomaly map of the Weddell Sea region demonstrates that features of large areal extent, such as geologic provinces, fold-belts, ancient eratonic fragments and other regional structural features can be readily delineated. The map allows a comparison of regional magnetic features with similar-scale geological structures on geological and geophysical maps. It also provides a database for the future production of the ''Digital Magnetic Anomaly Map of Antarctica'' in the framework of the Scientific Committee on Antarctic Research/International Association of Geomagnetism and Aeronomy (SCAR/IAGA) compilation.