Pine Island Glacier and its drainage basin: results from radio echo-sounding

first_imgRetreat of the grounding lines of West Antarctic ice streams may lead to the collapse of the West Antarctic ice sheet. Pine Island Glacier has been pinpointed as an ice stream in which rapid retreat is likely, especially as it is not buttressed by an ice shelf. Radio echo-sounding flights have produced a longitudinal thickness profile for the glacier. The ice presently rests on a bedrock sill which may play a crucial role in controlling the position of the grounding line. The profile can be fitted to a steadystate model but this alone is not adequate to determine steady- or non-steady-state behaviour. Landsat images show that the ice front undergoes periodic calving. Mass-balance calculations suggest that accumulation in the catchment may exceed ablation by a factor of 2. However, accumulation data are poor and there is no firm evidence of a build-up of ice within the Pine Island Glacier drainage basin.last_img read more

Experimental evaluation of the effectiveness of weighting regimes in reducing seabird by-catch in the longline toothfish fishery around South Georgia

first_imgA series of experiments was carried out in February 1999 at South Georgia (Subarea 48.3) to examine the effects of different weighting regimes on the incidental mortality of birds caught on longlines fishing for toothfish (Dissostichus spp.). Three regimes were examined, with weights of 4.25,8.5 and 12.75 kg attached at 40 m intervals on a Spanishrigged longline. There was a significant reduction in bird mortality when 8.5 kg was usedcompared to 4.25 kg, but no further significant reduction when 12.75 kg was used. Therefore to minimise seabird by-catch, line-weighting regimes of at least 8.5 kg at 40 mintervals should be used. Results suggested that seabird by-catch on lines using effective weighting regimes may be even further reduced where all lines being set in the vicinity use effective line-weighting regimes. The importance of a good design in experiments of this type is emphasised, because even though conditions may be held as constant as possible within experiments, the ability to separate treatment effects from other sources ofvariation (e.g. environmental factors) must be preserved.last_img read more

Space Plasma Exploration by Active Radar (SPEAR): an overview of a future radar facility

first_imgSPEAR is a new polar cap HF radar facility which is to be deployed on Svalbard. The principal capabilities of SPEAR will include the generation of artificial plasma irregularities, operation as an ‘all-sky’ HF radar, the excitation of ULF waves, and remote sounding of the magnetosphere. Operation of SPEAR in conjunction with the multitude of other instruments on Svalbard, including the EISCAT Svalbard radar, and the overlap of its extensive field-of-view with that of several of the HF radars in the SuperDARN network, will enable in-depth diagnosis of many geophysical and plasma phenomena associated with the cusp region and the substorm expansion phase. Moreover, its ability to produce artificial radar aurora will provide a means for the other instruments to undertake polar cap plasma physics experiments in a controlled manner. Another potential use of the facility is in ‘field-line tagging’ experiments, for coordinated ground-satellite experiments. Here the scientific objectives of SPEAR are detailed, along with the proposed technical specifications of the system.last_img read more

Tardigrade remains from lake sediments

first_imgRemains of tardigrades have rarely been reported to preserve in sediments, resulting in the absence of important ecological and biogeographic information that they could provide. However, a study of faunal microfossils in Antarctic lake sediment cores has shown that tardigrade eggs and occasionally exuvia can be abundant. Eggs from at least five tardigrade species were identified in sediment cores from six lakes from across the continent, with abundances up to 6,000 (g(-1) dry wt.). It is likely that the cold temperatures and absence of benthic grazers in Antarctic lakes results in particularly good preservation conditions, though it may also be a function of population density. The conservation of tardigrade eggs and exuvia in lake sediments enables a better understanding of paleodistributions and effects of environmental changes for this phylum that cannot otherwise be obtained.last_img read more

Association of the coprophilous fungus Pirella circinans with an indigenous beetle on the sub-Antarctic Bird Island

first_imgThe zygomycete fungus Pirella circinans was isolated from cadavers of the beetle Hydromedion sparsutum from diverse sites on the sub-Antarctic Bird Island and was found to be the dominant or sole fungal coloniser during the primary degradation of cadavers. The fungus was observed to grow and colonise cadavers from discrete areas of the beetle carapace, some of which were not affected by alcohol surface sterilisation. The fungus is commonly reported from the dung of rodents and other small mammals, both of which are absent from Bird Island. Recovery of P. circinans as the only fungus from beetle cadavers is unusual and may indicate a close association between the beetle and the fungus.last_img

Reconstructed streamflow for Citarum River, Java, Indonesia: linkages to tropical climate dynamics

first_imgThe Citarum river basin of western Java, Indonesia, which supplies water to 10 million residents in Jakarta, has become increasingly vulnerable to anthropogenic change. Citarum’s streamflow record, only similar to 45 years in length (1963-present), is too short for understanding the full range of hydrometeorological variability in this important region. Here we present a tree-ring based reconstruction of September-November Citarum streamflow (AD 1759-2006), one of the first such records available for monsoon Asia. Close coupling is observed between decreased tree growth and low streamflow levels, which in turn are associated with drought caused by ENSO warm events in the tropical Pacific and Indian Ocean positive dipole-type variability. Over the full length of record, reconstructed variance was at its weakest during the interval from similar to 1905-1960, overlapping with a period of unusually-low variability (1920-1960) in the ENSO-Indian Ocean dipole systems. In subsequent decades, increased variance in both the streamflow anomalies and a coral-based SST reconstruction of the Indian Ocean Dipole Mode signal the potential for intensified drought activity and related consequences for water supply and crop productivity in western Java, where much of the country’s rice is grown.last_img read more

Energy and ozone fluxes over sea ice

first_imgWe present surface layer measurements made over Hudson Bay seaice during February/March 2008 from the COBRA (Impact of combined iodine and bromine release on the Arctic atmosphere) experiment which formed part of the International OASIS (Ocean-Atmosphere-SeaIce-Snowpack) IPY programme. All components of the local surface energy balance were measured and it was defined by net radiative cooling throughout most of the day, mainly balanced by the conductive heat flux from the warmer sea water to the cooler seaice at the surface, and a small net radiative warming for a few hours after midday. Unique ground-level ozonefluxes were measured by eddy covariance and deposition velocities ranged from +0.5 mm s−1 (deposition) to −1.5 mm s−1 (emission). Ozone profile measurements suggested ozoneflux divergence within the surface layer. The observed bi-directional fluxes and flux divergence with height reveal the complexity of surface ozonefluxes in the Arctic spring time surface layer, and show that ozone exchange with the seaice surface is best probed using the eddy covariance method alongside frequent or continuous profile measurements. In this study, the local in-situ ozone-halogen photochemistry was identified as weakly controlling the measured ozoneflux, whereas horizontal advection and vertical mixing were considered more important in influencing fluxes. Under these conditions, several measurement sites would be desirable in order to quantify the contribution of advection to the local surface exchange.last_img read more

Identifying predictable foraging habitats for a wide-ranging marine predator using ensemble ecological niche models

first_imgAim Ecological niche modelling can provide valuable insight into species’ environmental preferences and aid the identification of key habitats for populations of conservation concern. Here, we integrate biologging, satellite remote-sensing and ensemble ecological niche models (EENMs) to identify predictable foraging habitats for a globally important population of the grey-headed albatross (GHA) Thalassarche chrysostoma. Location Bird Island, South Georgia; Southern Atlantic Ocean. Methods GPS and geolocation-immersion loggers were used to track at-sea movements and activity patterns of GHA over two breeding seasons (n = 55; brood-guard). Immersion frequency (landings per 10-min interval) was used to define foraging events. EENM combining Generalized Additive Models (GAM), MaxEnt, Random Forest (RF) and Boosted Regression Trees (BRT) identified the biophysical conditions characterizing the locations of foraging events, using time-matched oceanographic predictors (Sea Surface Temperature, SST; chlorophyll a, chl-a; thermal front frequency, TFreq; depth). Model performance was assessed through iterative cross-validation and extrapolative performance through cross-validation among years. Results Predictable foraging habitats identified by EENM spanned neritic ( 0.5 mg m−3) and frequent manifestation of mesoscale thermal fronts. Our results confirm previous indications that GHA exploit enhanced foraging opportunities associated with frontal systems and objectively identify the APFZ as a region of high foraging habitat suitability. Moreover, at the spatial and temporal scales investigated here, the performance of multi-model ensembles was superior to that of single-algorithm models, and cross-validation among years indicated reasonable extrapolative performance. Main conclusions EENM techniques are useful for integrating the predictions of several single-algorithm models, reducing potential bias and increasing confidence in predictions. Our analysis highlights the value of EENM for use with movement data in identifying at-sea habitats of wide-ranging marine predators, with clear implications for conservation and management.last_img read more

Utah Baseball Begins Fall Practice

first_img Written by Tags: Chandler Anderson/Corvallis Knights/Dixie State/Smith’s Ballpark/Utah Baseball/Utah Valley/West Coast League September 17, 2018 /Sports News – Local Utah Baseball Begins Fall Practice Brad James FacebookTwitterLinkedInEmailSALT LAKE CITY-Monday, Utah Baseball commenced its fall season with its first practice.The Utes feature 19 returning players from last season, including star Chandler Anderson of Park City, Utah.While playing with the Corvallis Knights of the West Coast League this summer, he led them to a league title by hitting .337 and belting 34 RBI.He also netted 22 stolen bases and was second on the team in runs scored, with 40.This fall, the Utes will have two games and 12 intersquad scrimmages.The first game of this season for the Utes is October 6 at home against Utah Valley and they will travel to St. George to face Dixie State October 27.The Utes’ first intersquad scrimmage is Friday at 3:15 p.m. and the final one is slated for Tuesday October 23.The Utes will have two scrimmages at Smith’s Ballpark in Salt Lake City September 28 and 29.last_img read more

RSL Signs Vazquez To Homegrown Contract

first_img Written by FacebookTwitterLinkedInEmail(Sandy, UT)  —  Local teenager Julian Vazquez is now a member of Real Salt Lake.The franchise signed the 17-year-old to a homegrown contract over the weekend.  Vazquez used to play for Ridgeline High School in Cache County, but has spent the past two years in the Real Salt Lake Academy. October 8, 2018 /Sports News – Local RSL Signs Vazquez To Homegrown Contract Tags: Julian Vazquez/Real Salt Lake/Real Salt Lake Academy Robert Lovelllast_img