first_imgField surveys of free-living terrestrial microarthropods were made during the 1994–95 summer at four sites in northern Marguerite Bay (Anchorage Island, Lagoon Island, Léonie Island, Rothera Point; c. 68°S, 68°W) and three on southern Alexander Island (Two Step Cliffs, Fossil Bluff, Ablation Valley; c. 71–72°S, 68°W). Detailed site descriptions are presented, as little previous information exists. Twenty species (four Collembola, 16 Acari) were recorded from the Marguerite Bay sites, with a maximum of 17 species at one site. A further four species (one Collembola, two Acari, one Diptera) have been recorded from the same area by other authors. Species diversity at these sites, in particular Léonie Island, is as great as at any known site elsewhere in the maritime Antarctic, although the total area of terrestrial habitat available is small. Individual species and total population densities are also similar to, if not greater than, published studies from the South Shetland and South Orkney Islands. None of the species is new to the maritime Antarctic, although the distributions of several are extended southwards. Only nine species (maximum seven at one site) were found on Alexander Island, concurrent with decreases in population densities to levels similar to those found in many continental Antarctic studies. This still represents a high species diversity for such a high latitude site. The richness of two sites, Ablation Valley and Mars Oasis (Two Step Cliffs), is unlikely to be repeated elsewhere on Alexander Island. The Alexander Island fauna is clearly related to that of the maritime Antarctic, as all except one species occur at more northerly sites elsewhere on the Antarctic Peninsula, and none in the continental Antarctic. One species, Friesia topo (Collembola), is known only from Alexander Island.last_img read more

first_imgTwo 788 m conductivity records from ice cores drilled at Dome C, Antarctica, provide an unprecedented opportunity to examine the past roughness of the Antarctic surface. By measuring the distribution of depth differences between synchronous events in the cores, the surface height distribution can be estimated during time intervals in the past. For the first time we publish a record of this type and consider its paleoclimatic implications. The paleoroughness, originating from sastrugi and dunes on the ice sheet surface, is hypothesized to be related to the wind speed, temperature, and accumulation rate during the period of preservation. The roughness record indicates only a slight decrease in the preserved surface roughness from the last glacial period (0.031 m root mean square (r.m.s.) of surface deviation) to the present (0.029 m r.m.s.). This result is surprising given the large change in temperature and accumulation rate that occurred during the last climatic transition. However, it could be consistent with modeling results suggesting low wind speeds on the East Antarctic Plateau during the last ice age if the possible influences of the accumulation and temperature changes are ignored. Additionally, the reliability of the Dome C ice core record is assessed, and the probability of short-term events being missing from the profile is determined. These results are of particular interest when constraining the proportion of events that may be synchronously matched with other ice cores. The principles and results present here allow inferences about the natural variation in ice core records generally.last_img read more

first_imgA model of the dynamics and thermodynamics of a plume of meltwater at the base of an ice shelf is presented. Such ice shelf water plumes may become supercooled and deposit marine ice if they rise (because of the pressure decrease in the in situ freezing temperature), so the model incorporates both melting and freezing at the ice shelf base and a multiple-size-class model of frazil ice dynamics and deposition. The plume is considered in two horizontal dimensions, so the influence of Coriolis forces is incorporated for the first time. It is found that rotation is extremely influential, with simulated plumes flowing in near-geostrophy because of the low friction at a smooth ice shelf base. As a result, an ice shelf water plume will only rise and become supercooled (and thus deposit marine ice) if it is constrained to flow upslope by topography. This result agrees with the observed distribution of marine ice under Filchner–Ronne Ice Shelf, Antarctica. In addition, it is found that the model only produces reasonable marine ice formation rates when an accurate ice shelf draft is used, implying that the characteristics of real ice shelf water plumes can only be captured using models with both rotation and a realistic topography.last_img read more

first_imgWe introduce a new bathymetric compilation of the area around South Georgia in the SouthernOcean. Using a variety of data sources including multi and single-beam swath bathymetry we haveconstructed a gridded bathymetric dataset of the shelf and near-shelf sea-floor areas. The grid has beenconstructed using a layered hierarchy dependent upon accuracy of each dataset. The spikes and errors havebeen checked both manually and with a novel semi-automated process. We discuss the resultingbathymetry and the potential uses of the new datasetlast_img read more

first_imgARGOS satellite telemetry and Global Location Sensors (geolocators) were used to identify the moult locations and the winter foraging dispersal of Adélie penguins after they left their breeding colonies on Signy Island in the South Orkney Islands. Animals were tracked during the period December 2004 to October 2005. All birds displayed a similar pattern of migratory behaviour, remaining away from colonies for approximately 9 months, at distances of up to 2,235 km. Moult locations were within the pack ice. Mean daily travel speeds to the moult locations were significantly faster when moving through open water than through pack ice. Moult occurred during February/March within a narrow latitudinal range (65–71°S), at a mean distance of 126 km from the ice edge; the mean duration of individual moult was c. 18.6 days. After moult, penguins spent the subsequent winter months moving north or north-eastward within the expanding winter pack ice, at a mean distance of 216 km from the ice edge, and in areas with ice cover >80%. The penguins returned to the vicinity of their colony between September 26 and October 22, 2005. This dependence of Adélie penguins on sea ice habitat suggests that any further reductions in sea ice extent in the Weddell Sea region would potentially have important impacts on the population processes of this pagophilic species.last_img read more

first_imgAccurate prediction of global sea-level rise requires that we understand the cause of recent, widespread and intensifying1, 2 glacier acceleration along Antarctic ice-sheet coastal margins3. Atmospheric and oceanic forcing have the potential to reduce the thickness and extent of floating ice shelves, potentially limiting their ability to buttress the flow of grounded tributary glaciers4. Indeed, recent ice-shelf collapse led to retreat and acceleration of several glaciers on the Antarctic Peninsula5. But the extent and magnitude of ice-shelf thickness change, the underlying causes of such change, and its link to glacier flow rate are so poorly understood that its future impact on the ice sheets cannot yet be predicted3. Here we use satellite laser altimetry and modelling of the surface firn layer to reveal the circum-Antarctic pattern of ice-shelf thinning through increased basal melt. We deduce that this increased melt is the primary control of Antarctic ice-sheet loss, through a reduction in buttressing of the adjacent ice sheet leading to accelerated glacier flow2. The highest thinning rates occur where warm water at depth can access thick ice shelves via submarine troughs crossing the continental shelf. Wind forcing could explain the dominant patterns of both basal melting and the surface melting and collapse of Antarctic ice shelves, through ocean upwelling in the Amundsen6 and Bellingshausen7 seas, and atmospheric warming on the Antarctic Peninsula8. This implies that climate forcing through changing winds influences Antarctic ice-sheet mass balance, and hence global sea level, on annual to decadal timescales.last_img read more

first_imgOnce an ice sheet grows beyond a critical thickness, the basal thermal regime favors melting and development of subglacial water networks. Subglacial water is necessary for bedrock erosion, but the exact mechanisms that lead to preservation of subglacial topography are unclear. Here we resolve the freezing mechanisms that lead to long-term, high-altitude preservation across the Gamburtsev Subglacial Mountains in East Antarctica. Analyses of a comprehensive geophysical data set reveal a large-scale water network along valley floors. The ice sheet often drives subglacial water up steep topography where it freezes along high ridges beneath thinner ice. Statistical tests of hypsometry show the Gamburtsevs resemble younger midlatitude mountains, indicating exceptional preservation. We conclude that the Gamburtsevs have been shielded from erosion since the latest Eocene (∼34 Ma). These freezing mechanisms likely account for the spatial and temporal patterns of erosion and preservation seen in other glaciated mountain ranges.last_img read more

first_imgThe Arctic is a highly seasonal environment with a harsh climate and extensive sea ice cover during the winter. Consequently, most Arctic-breeding seabirds migrate south to reach more benign environmental conditions. Knowledge of migration routes and wintering areas is integral for successful conservation of these globally important breeding populations. In this study, we deployed light-level geolocators on female common eiders Somateria mollissima breeding in Kongsfjorden, Svalbard, to track movements during the non-breeding season. We retrieved functioning loggers from 47 individual birds in 2009–2013 and mapped their migration routes and wintering areas. Thirty-six birds (77 %) wintered around the Icelandic coast and 11 (23 %) off the coasts of North Norway. Autumn migration took place between late August and late December, and spring migration from late March to late May. The migration (ca 1700 km to Iceland and 1300 km to North Norway) lasted for about 4 days in autumn and 3 days in spring. Later arrival resulted in later nest initiation, implying a carry-over effect of winter conditions on subsequent breeding. Birds that migrated to Norway departed later from Svalbard in autumn and consequently spent less time in the wintering area than individuals that migrated to Iceland. As just two countries, Iceland and Norway, appear to host all common eiders from Svalbard during the winter, the new information provided by this study on the core areas and timing of migration should provide the impetus for improved bilateral conservation management of this important Arctic breeding population of common eiders.last_img read more

first_imgJanuary 15, 2019 /Sports News – National Scoreboard roundup — 1/14/19 FacebookTwitterLinkedInEmailiStock(NEW YORK) — Here are the scores from Monday’s sports events:NATIONAL BASKETBALL ASSOCIATIONBrooklyn 109, Boston 102Houston 112, Memphis 94Charlotte 108, San Antonio 93Utah 100, Detroit 94Sacramento 115, Portland 107New Orleans 121, L.A. Clippers 117NATIONAL HOCKEY LEAGUENew Jersey 8, Chicago 5Colorado 6, Toronto 3Philadelphia 7, Minnesota 4St. Louis 4, Washington 1OT Montreal 3, Boston 2Edmonton 7, Buffalo 2TOP-25 COLLEGE BASKETBALLOT Syracuse 95, (1) Duke 91(7) Kansas 80, Texas 78Pittsburgh 75, (11) Florida St. 62(19) Maryland 64, Wisconsin 60Nebraska 66, (25) Indiana 51Copyright © 2019, ABC Radio. All rights reserved. Written bycenter_img Beau Lundlast_img read more

first_img FLNG Gimi force majeure claim. (Credit: aymane jdidi from Pixabay) Gimi MS Corp. (the “Company”), a subsidiary of Golar LNG Ltd (Nasdaq: GLNG), received written notification of a force majeure claim (the “Notice”) from BP Mauritania Investments Ltd (“BP”) under the Lease and Operate Agreement, dated February 26, 2019, between the Company and BP (the “Agreement”), relating to the Greater Tortue Ahmeyim project.The Notice received from BP claims that due to the recent outbreak of the novel coronavirus (COVID-19) around the globe, BP is not able to be ready to receive the floating liquefied natural gas facility “GIMI” on the target connection date in 2022.BP estimates at this stage that the consequential delay caused by the claimed force majeure event is in the order of one year and that it is not currently possible to mitigate or shorten this delay. Golar has asked BP to clarify how a force majeure event discovered as recently as the end of March 2020 could immediately impact the schedule by an estimated one year.Based on the information received as of today the Company is engaging in clarification and an active dialogue with BP to establish the duration of the delay and the extent to which this has been caused by the claimed force majeure event. However, in anticipation of a potential delay, the Company has commenced discussions with its main building contractor, Keppel Shipyard Limited (“Keppel”), to re-schedule activities in order to reduce and reprofile its capital spending commitments for 2020 and 2021.The Company is evaluating the Notice and reserves all of its rights under the Agreement. Source: Company Press Release BP estimates at this stage that the consequential delay caused by the claimed force majeure event is in the order of one year and that it is not currently possible to mitigate or shorten this delaylast_img read more