Antarctic ice sheet topography, cavity geometry, and global bathymetry (RTopo 1.0.5-beta)

Sub-ice shelf circulation and freezing/melting rates in ocean general circulation models depend critically on an accurate and consistent representation of cavity geometry. Existing global or pan-Antarctic data sets have turned out to contain various inconsistencies and inaccuracies. The goal of this work is to compile independent regional fields into a global data set. We use the S-2004 global 1-minute bathymetry as the backbone and add an improved version of the BEDMAP topography for an area that roughly coincides with the Antarctic continental shelf. Locations of the merging line have been carefully adjusted in order to get the best out of each data set. High-resolution gridded data for upper and lower ice surface topography and cavity geometry of the Amery, Fimbul, Filchner-Ronne, Larsen C and George VI Ice Shelves, and for Pine Island Glacier have been carefully merged into the ambient ice and ocean topographies. Multibeam survey data for bathymetry in the former Larsen B cavity and the southeastern Bellingshausen Sea have been obtained from the data centers of Alfred Wegener Institute (AWI), British Antarctic Survey (BAS) and Lamont-Doherty Earth Observatory (LDEO), gridded, and again carefully merged into the existing bathymetry map. The global 1-minute dataset (RTopo-1 Version 1.0.5) has been split into two netCDF files. The first contains digital maps for global bedrock topography, ice bottom topography, and surface elevation. The second contains the auxiliary maps for data sources and the surface type mask. A regional subset that covers all variables for the region south of 50 deg S is also available in netCDF format. Datasets for the locations of grounding and coast lines are provided in ASCII format.

Sedimentology of core M74/4_1143-1

Periplatform ooze is an admixture of pelagic carbonate and sediment derived from neritic carbonate platforms. Compositional variations of periplatform ooze allow the rectonstruction of past sea-level changes. Periplatform ooze formed during sea-level highstands is finer grained and richer in aragonit through the elevated input of material from the flooded platform compared to periplatform ooze formed during the episodes of lowered sea level. In many cases, however, the sea floor around carbonate platforms is subjected to bottom currents which are expected to affect sediment composition, i.e. through winnowing of the fine fraction. The interaction of sea-level driven highstand shedding and current impact on the formation of periplatform ooze is influenced or even distorted by changing current activity, an integrated study using seismic, hydroacoustic and sedimentological data has been performed on periplatform ooze deposited in the Inner Sea of the Maldives. The Miocene to Pleistocene succession of drift deposits is subdivided into nine units; limits of seismostratigraphic units correspond to changes or turnarounds in grain size trends in cores recovered at ODP Site 716 and NEOMA Site 1143. For the Pleistocene it can be shown how changes in grain size occur in concert with sea-level changes and changes of the monsoonal system, which is thought to be a major driver bottom currents in the Maldives. A clear hightstand shedding pattern only appears in the data at a time of of relaxation of monsoonal strength during the last 315 ky. Results imply (1) that drift sediments provide a potential target for analyzing past changes in oceanic currents and (2) that the ooze composition bears a mixed signal of input and physical winnowing at the sea floor.

E-RUN version 1.0: Observational gridded runoff estimates for Europe, link to data in NetCDF format (68 MB)

River runoff is an essential climate variable as it is directly linked to the terrestrial water balance and controls a wide range of climatological and ecological processes. Despite its scientific and societal importance, there are to date no pan-European observation-based runoff estimates available. Here we employ a recently developed methodology to estimate monthly runoff rates on regular spatial grid in Europe. For this we first collect an unprecedented collection of river flow observations, combining information from three distinct data bases. Observed monthly runoff rates are first tested for homogeneity and then related to gridded atmospheric variables (E-OBS version 11) using machine learning. The resulting statistical model is then used to estimate monthly runoff rates (December 1950-December 2014) on a 0.5° × 0.5° grid. The performance of the newly derived runoff estimates is assessed in terms of cross validation. The paper closes with example applications, illustrating the potential of the new runoff estimates for climatological assessments and drought monitoring.

Optimization and improvement of NSCU 1.0. Universal Functional Tester produced by Evoleo Technologi

The aim of the project was to improve an existing testing machine that is produced by the company EVOLEO Technologies. New conceptions of each part have been invented in order to produce an innovative unit that combines optimal segments from the old construction with the new, improved ones. The machine is meant to be testing different kind of devices that use specific elements like: buttons, knobs, monitors. The main purpose is to create various concepts of components that could be changed in order to lower the cost, weight or to simplify the operating process. Figure 1. shows the already existing discussed device.

Testing the level of interactivity of institutional websites: From museums 1.0 to museums 2.0

The Internet has changed the way in which organizations communicate with their publics, and museums are not an exception. The consolidation of Web 2.0 has not only given museums access to a powerful new tool for disseminating information, but has involved significant changes in the relationship between institutions and their publics, facilitating and enhancing the interaction between them. The overall objective of this paper is to analyze the degree of interactivity implemented in the websites of major international art museums, in order to assess if museums are evolving towards more dialogic systems with relation to their publics. The results indicate that museums still have a low level of interactivity on their websites, both in the tools used to present information and the resources available for interaction with virtual visitors. But it has also observed that museums are progressively implementing interactive and dialogic sources, suggesting a clear trend towards new ways of managing these platforms in order to establish more participatory and collaborative communication systems with virtual users.

"1/0"

Combined media on photographic paper. 55" x 93", Jargomatique Series. Private Collection

Validación del software educativo Poliestudio 1.0: informe de investigación

PoliEstudio 1.0 is a computational tool, with free license, created to work with polynomial expressions in one variable and it was created by a team in which the authors of this article are part of. This article documents the qualitative validation performed to this software which main objective was to bring to the Costa Rican Educational System a validated educational software that can solve, partially, the problems that nowadays exists in the mathematic education of secondary students, particularly in the topics related to polynomial expressions in one variable and specifically to those students who are in eighth grade.

The surficial geology, sedimentology and geochemistry of the late glacial sediments and Paleozoic bedrock in the Campbellford area, Ontario, with special reference to the Dummer Complex /

The Dummer Complex extends 180 km along the Precambrian - Paleozoic contact from Tamworth to Lake Simcoe. It is composed of coarse, angular Paleozoic clasts in discontinuous, pitted, hummocky deposits. Deposits are usually separated by bare or boulder strewn bedrock, but have been found in the southern drumlinized till sheet. Dummer Complex deposits show rough alignment with ice-flow. Eskers cross-cut many of the deposits. Dummer sediment subfacies are defined on the basis of dominant coarse grain size and lithology, which relate directly to the underlying Paleozoic formation. Three subglacial tills are identified based on the degree of comminution and distance of transport; the immature facies of the Dummer Complex; the mature facies of the drumlinized till sheet and; the submature facies which is transitional. Carbonate geochemistry was used for till-bedrock correlation in various grain sizes. Of the 3 Paleozoic formations underlying the Dummer Complex, the Gull River Fm. is geochemically distinctive from the Bobcaygeon and Verulam Formations using Ca, Mg, Sr, Cu, Mn, Fe and Na. The Bobcaygeon Fm. and Verulam Fm. can be differentiated using Ca and the Sr/Ca ratio. The immature facies from 1.0 phi and finer is dominated by the non-carbonate, long distance transported component which decreases slightly downice. The submature till facies contains more long distance material than the immature facies. Sr and Mn can be used to correlate the Gull River immature till facies to the underlying bedrock the other subfacies could not be distinguished from each other or their respective source formation. This method proved to be ineffective for sediments with greater than 35% non-carbonate component, due to leaching of elements by the dissolving acid.The Dummer Complex is produced subglacially , as the compressional ice encounters the permeable Paleozoic carbonates. The increased shear strength of the ice and pore pressures in the carbonates results in the basal ice zones becoming debris ladden. Cleaner ice overrides the basal debris . laden dead ice which then acts as the glacier bed. During retreat, the Simcoe lobe stagnates as flow is cut-off by the Algonquin Highlands.

Sedimentological and clay mineralogical analysis of ODP sites in the central Fram Strait

This study presents the results of high-resolution sedimentological and clay mineralogical investigations on sediments from ODP Sites 908A and 909AlC located in the central Fram Strait. The objective was to reconstruct the paleoclimate and paleoceanography of the high northern latitudes since the middle Miocene. The sediments are characterised in particular by a distinctive input of ice-rafted material, which most probably occurs since 6 Ma and very likely since 15 Ma. A change in the source area at 1 1.2 Ma is clearly marked by variations within clay mineral composition and increasing accumulation rates. This is interpreted as a result of an increase in water mass exchange through the Fram Strait. A further period of increasing exchange between 4-3 Ma is identified by granulometric investigations and points to a synchronous intensification of deep water production in the North Atlantic during this time interval. A comparison of the components of coarse and clay fraction clearly shows that both are not delivered by the Same transport process. The input of the clay fraction can be related to transport mechanisms through sea ice and glaciers and very likely also through oceanic currents. A reconstruction of source areas for clay minerals is possible only with some restrictions. High smectite contents in middle and late Miocene sediments indicate a background signal produced by soil formation together with sediment input, possibly originating from the Greenland- Scotland Ridge. The applicability of clay mineral distribution as a climate proxy for the high northern latitudes can be confirmed. Based on a comparison of sediments from Site 909C, characterised by the smectite/illite and chlorite ratio, with regional and global climatic records (oxygen isotopes), a middle Miocene cooling phase between 14.8-14.6 Ma can be proposed. A further cooling phase between 10-9 Ma clearly shows similarities in its Progress toward drastic decrease in carbonate sedimentation and preservation in the eastern equatorial Pacific. The modification in sea water and atmosphere chemistry may represent a possible link due to the built-up of equatorial carbonate platforms. Between 4.8-4.6 Ma clay mineral distribution indicates a distinct cooling trend in the Fram Strait region. This is not accompanied by relevant glaciation, which would otherwise be indicated by the coarse fraction. The intensification of glaciation in the northern hemisphere is distinctly documented by a rapid increase of illite and chlorite starting from 3.3 Ma, which corresponds to oxygen isotope data trends from North Atlantic.

Grain size analysis of sediment core CRP-3 from the Ross Sea, Antarctica

Grain-size analyses by sieve and Sedigraph are presented for 115 samples of core from CRP-3, 12 km off the coast of south Victoria Land. The data provide a useful check on visual core descriptions. The geographic setting for the strata sampled, some 790 m of early Oligocene nearshore marine sediments with a persistent glacial influence, is reviewed, and sediment textures interpreted in that context. Sand textures from the CRP-3 samples in the lower part of the core suggest that deposition was initially primarily wave-dominated, but that at times the influence of the waves was over-ridden by episodes of rapid sedimentation. Sedimentary cycles, recognised in the visual description of the core above 485 mbsf, show an increasing proportion of mudstone in the middle of each cycle above 330 mbsf that is interpreted to record periodic sedimentation in deeper water. Sandstone textures in the lower and upper parts of each cycle are interpreted to record departure from and return to shoreface deposition with changes in sea level. Mudstone textures above 176 mbsf indicate sedimentation below wave base. Many of the textures in both sand and mud samples show the coarse 'tail' characteristic of ice-rafted debris, but others do not, indicating ice-free periods. Many sandstones below c. 200 mbsf have virtually no silt, but significant amounts of clay (6 to 17%) that is thought to be of post-depositional origin.

Grain size analysis of sediment coring site CRP-2 from the Ross Sea, Antarctica

The purpose of this note is to present results of grain size analyses from 118 samples of the CRP-2/2A core using sieve and Sedigraph techniques. The samples were selected to represent the range of facies encountered, and tend to become more widely spaced with depth. Fifteen came from the upper 27 m of Quaternary and Pliocene sediments, 62 from the early Miocene-late Oligocene strata (27 to 307 mbsf), and 41 from the early Oligocene strata beneath (307 to 624 mbsf). The results are intended to provide reference data for lithological descriptions in the core logs (Cape Roberts Science Team, 1999), and to help with facies interpretation. The analytical technique used for determining size frequency of the sand fraction in our samples (sieving) is simple, physical and widely practised for over a century. Thus it provides a useful reference point for analyses produced by other faster and more sophisticated techniques, such as the Malvern laser particle size analysis system (Woolfe et al., 2000), and estimates derived from measurements taken with down-hole logging tools (Bücker, pers. com., 1999).