Showing 11923 items
1 December, 2001 by Gareth Chisham, Mervyn Freeman, Michael Pinnock
This paper sets out a critical test of the antiparallel merging hypothesis. For the conflicting theories of antiparallel and subsolar reconnection, we model the location of reconnection regions on the…Read more on An ionospheric convection signature of antiparallel reconnection
1 December, 2001 by Mervyn Freeman
Auroral spirals are the largest vortex structures that appear in auroral arcs. Their diameters vary from tens to hundreds of kilometers. We have collected an all-sky camera data set of…1 December, 2001
On August 18, 1999, Cassini flew by the Earth on its way to Saturn. The Cassini Earth swing-by was the fastest traversal of the Earth's magnetosphere to date. The spacecraft…1 October, 2001 by Richard Hindmarsh, Richard Hindmarsh
Ice‐sheet flows can be channelled by perturbations in the basal topography or in the sliding coefficient. These lead to spatial variation in the steady profile, the flux and the dissipative…Read more on Influence of channelling on heating in ice-sheet flows
15 September, 2001 by Keith Nicholls
This is the first large-scale modeling study of iceberg trajectories and melt rates in the Southern Ocean. An iceberg model was seeded with climatological iceberg calving rates based on a…Read more on Iceberg trajectory modeling and meltwater injection in the Southern Ocean
1 September, 2001 by Robert Mulvaney
The atmospheric trend of methane isotopic ratios since the mid-20th century has been reconstructed from Antarctic firn air. High volume air samples were extracted at several depth levels at two…31 July, 2001
A considerable fraction of the solar wind energy that crosses the magnetopause ends up in the high-latitude thermo sphere-io no sphere system as a result of Joule heating, the consequences…Read more on The variability of Joule heating and its effects on the ionosphere and thermosphere
1 July, 2001 by Mai Mai Lam
This paper tests the Araki [1994] computational model of the Earth-ionosphere system during geomagnetic sudden commencement (sc). In particular, we test the model's ability to predict the signs of the…Read more on A case study test of Araki’s physical model of geomagnetic sudden commencement
1 July, 2001 by Richard Horne
Intense interest currently exists in determining the roles played by various wave-particle interactions in the acceleration of electrons to relativistic energies during/following geomagnetic storms. Here we present a survey of…15 June, 2001 by Keith Makinson, Keith Nicholls
We have made oceanographic measurements at two sites beneath the southern Filchner-Ronne Ice Shelf. Hot-water drilled access holes were made during January 1999, allowing conductivity-temperature-depth (CTD) profiling and the deployment…10 June, 2001 by Adrian Jenkins, Andy Smith, David Vaughan, Hugh Corr, Richard Hindmarsh, Richard Hindmarsh
Measurements of ice thickness on the Antarctic ice sheet collected during surveys undertaken over the past 50 years have been brought together into a single database. From these data, a…Read more on BEDMAP: A new ice thickness and subglacial topographic model of Antarctica
1 June, 2001 by Peter Kirsch
Results from an intercomparison campaign of ultraviolet spectroradiometers that was organized at Nea Michaniona, Greece July, 1–13 1997, are presented. Nineteen instrument systems from 15 different countries took part and…Read more on SUSPEN intercomparison of ultraviolet spectroradiometers
1 June, 2001 by Adrian Jenkins, Richard Hindmarsh, Richard Hindmarsh
We use an ice‐sheet model to show that (i) margins of marine ice‐sheets can be expected to be frozen to the bed, except where ice‐streams discharge; (ii) 20–50km retreats induced…Read more on Centurial‐millenial ice‐rafted debris pulses from ablating marine ice sheets
27 May, 2001 by John Turner, Thomas Lachlan-Cope
In polar regions, satellite microwave radiometry has not been successful in measuring the total water vapor (TWV) in the atmosphere. The difficulties faced in these regions arise from the very…1 April, 2001 by Anna Jones, Eric Wolff
It has been shown that NOx is produced photochemically within the snowpack of polar regions. If emitted to the atmosphere, this process could be a major source of NOx in…Read more on Measurements of NOx emissions from the Antarctic snowpack
1 April, 2001 by Michael Meredith
Two hydrographic and δ18O transects across Fram Strait (Aug–Sept 1997, 1998) are used to examine freshwater contributions to the East Greenland Current (EGC). The EGC featured up to ∼16% meteoric…Read more on Freshwater fluxes through the western Fram Strait
1 March, 2001
We report simultaneous measurements of the O2(¹Δ) and O2(¹Σ) airglow volume emission rate profiles in the daytime mesosphere. We use these measurements to derive ozone concentrations separately from each airglow.…1 February, 2001 by Anna Jones, Howard Roscoe
Calculations of equivalent length from an artificial advected tracer provide new insight into the isentropic transport processes occurring within the Antarctic stratospheric vortex. These calculations show two distinct regions of…1 January, 2001 by John King
The Ronne polynya formed in the Weddell Sea, Antarctica, during the period November 1997-February 1998 to an extent not seen previously in the 25 years of all-weather satellite observations. The…Read more on The Ronne polynya of 1997/98: observations of air-ice-ocean interaction
1 January, 2001 by Paul Rodhouse
A comprehensive study of octopodids in the Weddell Sea was conducted during cruise ANT XIII/3 of RV "Polarstern". The study yielded eight species or incirrate octopodids, three of which were…Read more on A study on octopodids from the eastern Weddell Sea, Antarctica
1 January, 2001
The relationship between fitness and parental similarity has been dominated by studies of how inbreeding depression lowers fecundity in incestuous matings. A widespread implicit assumption is that adult fitness (reproduction)…Read more on The influence of parental relatedness on reproductive success
1 January, 2001 by Paul Rodhouse
Exploited populations of ommastrephidsquid are found under a wide range of oceanographic regimes. However, to date most scientific attention has focussed on those found in northern hemisphere western boundary current…1 January, 2001 by Paul Rodhouse
Age, growth and populationstructure of the jumboflyingsquid, Dosidicusgigas, from the jig fishery in Peruvianwaters in 1992 were determined by reading daily increments in ground and polished sections of statoliths. The…1 January, 2001
An experiment involving the supplementary feeding of pups was conducted on Antarctic fur seals to investigate the factors influencing maternal foraging-attendance cycles and the differential use of nutritional resources for…1 January, 2001
The metabolism of 52–73-day old Antarcticfursealpups from Bird Island, South Georgia, was investigated during fasting periods of normal duration while their mothers were at sea foraging. Body mass decreased exponentially…Read more on Fasting metabolism in Antarctic fur seal (Arctocephalus gazella) pups
1 January, 2001
Age composition is fundamental to understanding the population dynamics and productivity of a fish stock. The use of scales to estimate age can result in large errors in age data…1 January, 2001
Given the importance of copepods in the Southern Ocean food web, there are few assessments of their N budgets or their role in regenerating N. In this study we measured…Read more on Ammonium regeneration by Antarctic mesozooplankton: an allometric approach
1 January, 2001 by Peter Ward
The South Georgia region is characterised by high biomass and productivity of phytoplankton, zooplankton and vertebrate predators. Important commercial fisheries have been based at the island since the late 1700s,…Read more on South Georgia, Antarctica: a productive, cold water pelagic ecosystem
1 January, 2001 by Roger Worland, William Block
The sub-AntarcticbeetleHydromedion sparsutum (Coleoptera, Perimylopidae) is common locally on the island of South Georgia where sub-zero temperatures can be experienced in any month of the year. Larvae were known to…1 January, 2001
This paper reports briefly an attempt to examine the tectonic evolution of the Scotia Sea region, in the context of the use of broad-band seismological techniques there. Such techniques can…Read more on Evolution of the Scotia Sea region: relevance to broad-band seismology
1 January, 2001
The ScotiaSea and surrounding Scotia Arc have evolved over the past 40 Ma, by extension behind an east-migrating subduction zone, at the boundary between the South American (SAM) and Antarctic…1 January, 2001 by Rod Arnold
Overgrowth competition, sub-lethal mortality (some zooids killed but colony survives) and subsequent growth from fragments, and diversity of communities encrusting rocks (pebble through to boulder size) were examined from five…1 January, 2001 by Rod Arnold
The Madagascar coast (both) has a higher density and diversity of hermit crabs than is known from any other localiy in the western Indian Ocean. Of the 20 species occurring…Read more on Ecology of subtropical hermit crabs in S.W. Madagascar: cluster structure and function
1 January, 2001 by Rod Arnold
Growth and mortality of 3 species (Inversiula nutrix, Celleporella bougainvillei, Fenestrulina rugula) of encrusting bryozoans were examined from 5 Antarctic localities, along a latitudinal gradient. Typically, growth in marine invertebrates…1 January, 2001 by Roger Worland, William Block
The effect of different culture methods, cold acclimation and desiccation on the supercooling point (SCP), the melting point (MP) of fluids and the quantity of water freezing (osmotically active water)…Read more on Experimental studies on cold survival of enchytraeid cocoons
1 January, 2001 by Richard Phillips
This study combines conventional dietary assessment with stable isotope techniques to describe Great Skua (Stercorarius skua) diet. Stable carbon and nitrogen isotope ratios in feathers of Great Skua chicks collected…1 January, 2001
The adaptation of Imaging Doppler Interferometry (IDI) to the dynasonde deployed at the Bear Lake Observatory (41.9°N, 111.4°W) in northeastern Utah enables the routine measurement of mesospheric dynamics. Influenced by…1 January, 2001
We investigated foraging behavior of Wandering Albatrosses (Diomedea exulans) breeding at South Georgia to assess how sex and season-specific foraging patterns relate to provisioning performance. We estimated Wandering Albatross chicks…1 January, 2001 by Peter Convey, William Block
Body-water content of field-fresh samples of the springtail, Cryptopygus antarcticus Willem (Collembola, Isotomidae) was measured at monthly intervals over 11 years (1984–1995) at Signy Island, in the maritime Antarctic. A…1 January, 2001 by Roger Worland, William Block
Ice nucleation was studied in field-fresh and acclimated (4°C without food for 11–20 days) samples of the springtail Cryptopygus antarcticus Willem (Collembola, Isotomidae) at Rothera Research Station, Adelaide Island on…1 January, 2001 by Iain Staniland
The study aimed to test the utility of instruments deployed on marine mammals for measuring physical oceanographic variation and, using this method, to examine temperature variation in the coastal waters…Read more on Measurement of ocean temperatures using instruments carried by Antarctic fur seals
1 January, 2001
1 This study examined the changing status of the marine ecosystem at the island of South Georgia (Southern Ocean) using up to 27 variables measured over 22 years from three…Read more on Monitoring a marine ecosystem using responses of upper trophic level predators
1 January, 2001
Multi-frequency acoustic data (18, 38 and 120 kHz) were collected in conjunction with pelagic trawl sampling for gelatinous macrozooplankton during a cruise to the Namibian Benguela in September 1999. Sampling…Read more on Acoustic observations of jellyfish in the Namibian Benguela
1 January, 2001
The Autonomous Underwater Vehicle (AUV) Autosub-1 made observations of the sea surface with an upward-looking echosounder during fish surveys in the vicinity of Shetland and Orkney (North Sea) in July…1 January, 2001 by Andrew Clarke
The seasonal pattern of food intake and tissue energy status was measured over a 2 year period for two populations of the common Antarctic echinoid Sterechinus neumayeri living on contrasting…1 January, 2001
Seasonal changes in feeding activity, metabolic rate and major tissue energy concentrations of the infaunal bivalve Laternula elliptica were monitored over a 12 degrees month period in relation to phytoplankton…1 January, 2001 by Andrew Clarke
Many benthic marine invertebrates exhibit a seasonal cycle in activities such as feeding, growth and reproduction. In temperate regions, this seasonality is typically correlated with coincident cycles in photoperiod, temperature…1 January, 2001 by Lloyd Peck
Oxygen consumption (MO2) and ammonium excretion rates were recorded monthly over 2 yr for the regular Antarctic echinoid Sterechinus neumayeri to investigate metabolic activity in relation to seasonal food limitation…1 January, 2001
Bathymetric and seismic data show that the southernmost segment of the EastScotia Ridge (segment E9) is anomalous in its curved plan form, and in the presence of a large axial…1 January, 2001
The population structure of black-browed (Thalassarche melanophris and T. impavida) and grey-headed (T. chrysostoma) albatrosses was examined using both mitochondrial DNA (mtDNA) and microsatellite analyses. mtDNA sequences from 73 black-browed…1 January, 2001
The discovery of gullies and debris aprons raises the question of the existence of aqueousenvironments on Mars in recent geological times and its astrobiological implications. Three cases of such environments…Read more on Recent aqueous environments in Martian impact craters: an astrobiological perspective
1 January, 2001
A single fossil leaf of Nothofagus from CRP-3 drillhole in the Victoria Land Basin provides further evidence for woody vegetation in the Tertiary of East Antarctica. The plicate vernation of…1 January, 2001
Coniferous foliage from the Albian of AlexanderIsland, Antarctica, is assigned to the Araucariaceae, Podocarpaceae, and Taxodiaceae based on attached or associated fertile remains. Araucarian foliage represented by Araucaria alexandrensis sp.…1 January, 2001
Whistler-mode waves propagating to ground stations along geomagnetic-field-aligned paths provide powerful tools for investigating bulk motions of the magnetospheric plasma and thus the corresponding convection electric fields. Natural whistlers from…1 January, 2001
New data suggest that the eastern margin of the Argentine Precordillera terrane comprises Grenvillian basement and a sedimentary cover derived from it that were together affected by Middle Ordovician deformation…1 January, 2001 by John King
Calculated surface fluxes from seven surface layer parameterizations are verified against 45 months of observations from Halley, Antarctica, with a temporal resolution of 1 h. The surface layer parameterizations are…1 January, 2001
Observations of recent volcanic eruptions in Iceland and detailed studies of sub-glacially erupted deposits and the interaction of lava and pyroclastic flows with snow and ice have provided important new…Read more on Study of volcano/ice interactions gains momentum
1 January, 2001
Recently, the paradigm that the dynamic magnetosphere displays sandpile-type phenomenology has been advanced, in which energy dissipation is by means of avalanches which do not have an intrinsic scale. This…1 January, 2001
The characterization of global energy storage and release in the coupled solar wind-magnetosphere system remains one of the fundamental problems of space physics. Recently, it has been realised that a…Read more on Avalanching and self organised criticality, a paradigm for geomagnetic activity?
1 January, 2001 by Gareth Chisham, Michael Pinnock
In the high-latitude dayside ionosphere, the movement of the HF radar spectral width boundary (SWB) provides a good proxy for the movement of the open-closed field line boundary around magnetic…1 January, 2001 by Andrew Clarke
Marine organisms in Antarctica live in an environment which exhibits variability in physical processes over a wide range of temporal scales, from seconds to millennia. This time scale tends to…1 January, 2001 by Mark Clilverd
During the total solar eclipse observed in Europe on August 11, 1999, measurements were made of the amplitude and phase of four VLF transmitters in the frequency range 16–24 kHz.…Read more on Total solar eclipse effects on VLF signals: observations and modeling
1 January, 2001
Astrobiology has recently been feted as a science for the twenty-first century. Founded as a science in the Soviet Union in 1953, its recent manifestation has been accompanied by a…1 January, 2001
Ultraviolet radiation is an important natural physical influence on organism function and ecosystem interactions. The UVradiation fluxes in extraterrestrial environments are substantially different from those experienced on Earth. On Mars,…1 January, 2001
The Martianpolar ice caps are regions of substantial scientific interest, being the most dynamic regions of Mars. They are volatile sinks and thus closely linked to Martian climatic conditions. Because…Read more on Martian polar expeditions: problems and solutions
1 January, 2001
In the Archean era (3.8–2.5 Ga ago) the Earth probably lacked a protective ozone column. Using data obtained in the Earth’s orbit on the inactivation of Bacillus subtilis spores we…1 January, 2001
The input of nutrients into arctic polar deserts, aided by some physical processes, can result in localized areas of high biological productivity--"micro-oases." We examined the vegetation cover, and microbial and…1 January, 2001
During July 2000 we used an electronic personal dosimeter (X-2000) and a biological dosimeter (Deutsches Zentrum für Luft- und Raumfahrt: Biofilm) to characterize the UV radiation exposure of arctic field…1 January, 2001
In this paper, numerical weather prediction analyses from four major centers are compared—the Australian Bureau of Meteorology (ABM), the European Centre for Medium-Range Weather Forecasts (ECMWF), the U.S. National Centers…1 January, 2001 by Adrian Jenkins, David Vaughan
We present newly acquired airborne radar data showing ice thickness and surface elevation for Pine Island Glacier, Antarctica. These data, when combined with earlier measurements, suggest the presence of a…Read more on Investigations of an ‘ice plain’ in the mouth of Pine Island Glacier, Antarctica
1 January, 2001 by Alistair Crame
There is evidence from the fossil record to suggest that latitudinal gradients in taxonomic diversity may be time-invariant features, although almost certainly not on the same scale as that seen…Read more on Taxonomic diversity gradients through geological time
1 January, 2001
Early Paleozoic orogenesis has been recognized along the southern African (Saldanian orogeny) and East Antarctic (Ross orogeny) sectors of the Gondwana paleo- Pacific margin. However, the absence of a contemporaneous…1 January, 2001
Since the early 1990s, the Cape Roberts Project has been working to document, through sediment drilling, the proximal record of Antarctic ice sheet history and climate for the southwestern part…1 January, 2001
A total of eighteen species of marine ostracods, in at least twelve genera, have been recovered from Early and Late Oligocene glacio-marine sediments from boreholes CRP-3 and CRP-2/2A in the…1 January, 2001 by Mark Clilverd
There are two distinctly different causes of phase and amplitude perturbations of subionospheric VLF transmissions (termed “Trimpis”): (1) ionization enhancement in the ionospheric D region due to whistler-induced electron precipitation…1 January, 2001
Mackerel icefish (Cllanzpsocephal[~gsz rnnnvi) are widespread on the South Georgia shelf, Antarctica, and have been fished commercially since the early 1970s. They are known to feed predominantly on krill. An…Read more on Variations in condition indices of mackerel icefish at South Georgia from 1972 to 1997
1 January, 2001
Historical information on the distribution of spawning and larval mackerel icefish (Champsocephalus gunnari) within CCAMLR Subarea 48.3 (South Georgia and Shag Rocks) is assessed. This is considered alongside new data…Read more on Spawning locations of mackerel icefish at South Georgia
1 January, 2001
Silicified gymnosperm trunks usually more than 30 cm in diameter and several metres in length occur abundantly in the lower part of the mid-AptianCerroNegroFormation, which crops out on ByersPeninsula, LivingstonIsland,…1 January, 2001
The leaf longevity and seasonal timing of leaf abscission within a plant community is closely related to climate, a phenomenon referred to as leaf phenology. In this paper the leaf…Read more on Leaf phenology of some mid-Cretaceous polar forests, Alexander Island, Antarctica
1 January, 2001
The biodiversity and terrestrial ecology of the Late Albian Triton Point Formation (Fossil Bluff Group), Alexander Island, Antarctica is analysed to improve our understanding of polar biomes during the mid-Cretaceous…1 January, 2001
The botanical identity and facies distribution of fossil charcoal is described from Middle to Late Cenomanian (90–94 Ma) fluvial to estuarine units at Pecínov quarry, near Prague, Czech Republic. Braided…1 January, 2001 by Adrian Fox
Automatic digital elevation model (DEM) generation has become an established technique within mapping agencies. This paper assesses the effectiveness of automatic DEM generation using area-based matching for glaciated terrain in…1 January, 2001
It has been suggested previously that the presence and abundance of indigenous species have a marked influence on the likelihood of invasion of a community. It has also been suggested…1 January, 2001 by Lloyd Peck
The metabolism of a coastal mysid population ŽPraunus flexuosus. from the West Solent South England. has been studied in different seasons winter, spring and summer.. Metabolic responses to copper 0,…Read more on Effects of copper exposure on the metabolism of the mysid Praunus flexuosus
1 January, 2001 by Lloyd Peck
The reproductive biology, in response to temperature, season and copper, of a coastal population of opossum shrimps (Crustacea: Mysidacea) was measured. The reproductive pattern for Praunus flexuosus at Keyhaven (west…Read more on Reproduction, seasonality, and copper toxicity in the coastal mysid Praunus flexuosus
1 January, 2001
Microsatellites were used to conduct an analysis of paternity of Antarctic fur seals (Arctocephalus gazella) from Bird Island, South Georgia. At most, only 28% of pups at our study site…1 January, 2001
To assess the biological implications of ozone depletion over the Antarctic Peninsula, the ultraviolet (UV) regime of two Antarctic cyanobacterial communities (composed of Leptolyngbya sp. and Phormidium sp.) was manipulated…Read more on Tolerance of Antarctic cyanobacterial mats to enhanced UV radiation
1 January, 2001 by Paul Rodhouse
Acoustic survey methods are now widely used for stock assessments of finfish, both those with and without swimbladders, but their application to squid stocks has been limited in the past,…Read more on Investigations of squid stocks using acoustic survey methods