Your search

Har livet på Jorda blitt ført hit fra tidligere liv på planeten Mars? I 1996 hevdet en gruppe forskere at en meteoritt fra Mars faktisk inneholdt spor etter organisk liv. Hvis dette virkelig var tilfelle, ville det medføre en revolusjon for vårt syn på verden og det univers vi befinner oss i. Men vitenskapsfolk besitter sunn skepsis, og hos dem kommer ikke tvilen tiltalte til gode. Nå mener de fleste ekspertene at funnet var for godt til å være sant.

A fast-flowing tributary of Recovery ice stream penetrates more than 500 km into the interior of East Antarctica. Recent satellite-based studies found surface features in the onset area of this tributary that indicate a significant subglacial hydraulic system, including four large smooth basins, the typical surface expression of large subglacial lakes, as well as eleven smaller areas over which ice-sheet surface elevations rapidly changed by discharge/filling of subglacial water. Here we present the first ice-penetrating radar evidence of subglacial conditions in this area. We identified a distinct ice-water interface only over a limited area within the boundaries of the investigated large smooth basins, previously hypothesized to be water-filled lakes. The radar characteristics in some areas are similar to those of a drained lake, indicating that parts of the bed are wet, but not a typical lake. We also find evidence for discrete water bodies outside of the lake boundaries. The lines of evidence indicate that the northern most two Recovery Lakes have recently drained.

We compare the present and last interglacial periods as recorded in Antarctic water stable isotope records now available at various temporal resolutions from six East Antarctic ice cores: Vostok, Taylor Dome, EPICA Dome C (EDC), EPICA Dronning Maud Land (EDML), Dome Fuji and the recent TALDICE ice core from Talos Dome. We first review the different modern site characteristics in terms of ice flow, meteorological conditions, precipitation intermittency and moisture origin, as depicted by meteorological data, atmospheric reanalyses and Lagrangian moisture source diagnostics. These different factors can indeed alter the relationships between temperature and water stable isotopes. Using five records with sufficient resolution on the EDC3 age scale, common features are quantified through principal component analyses. Consistent with instrumental records and atmospheric model results, the ice core data depict rather coherent and homogenous patterns in East Antarctica during the last two interglacials. Across the East Antarctic plateau, regional differences, with respect to the common East Antarctic signal, appear to have similar patterns during the current and last interglacials. We identify two abrupt shifts in isotopic records during the glacial inception at TALDICE and EDML, likely caused by regional sea ice expansion. These regional differences are discussed in terms of moisture origin and in terms of past changes in local elevation histories, which are compared to ice sheet model results. Our results suggest that elevation changes may contribute significantly to inter-site differences. These elevation changes may be underestimated by current ice sheet models.

Radar power returned from ice-sheet beds has been widely accepted as an indicator of bed conditions. However, the bed returned power also depends on englacial attenuation, which is primarily a function of ice temperature. Here, using a one-dimensional attenuation model, it is demonstrated that, in most cases, variations in bed returned power are dominated by variations in englacial attenuation, rather than bed reflectivity. Both accumulation rate and geothermal flux anomalies can interfere with the interpretation. With the consequence, analytical radar algorithms that have been widely accepted likely yield false delineations of wet/dry beds. More careful consideration is needed when diagnosing bed conditions. Spatial patterns of shallow englacial radar reflectors can be used as a proxy for accumulation rates, which affect ice temperature and thus returned power. I argue that it is necessary to simultaneously interpret the returned power and englacial-reflector patterns to improve the bed diagnosis.

Determining the present precise location of Amundsen's tent is a function of 1) the precision of Amundsen's navigation in 1911, 2) the flow of ice since then, and 3) the amount of burial by intervening snow fall. These factors are discussed and it is concluded that the best location that can be given for the tent in December 2011 is 89° 58′ 51″ S, 46° 14′ E, and lying 17 m below the present snow surface. The uncertainty in the position is 0.3 km, and is mainly related to uncertainties in the original positioning. It can be concluded with high certainty that the tent lies between 1.8 and 2.5 km from the South Pole.

Fram mot grunnlovsjubileet i 2014 vil det bli utarbeidet nasjonale rammefortellinger om utvalgte epoker og tema i kystens historie. Fortellingene lanseres under overskriften Fortellinger om kyst-Norge. Siden oppstarten i 2009 har det blitt produsert seks hefter. Det første heftet, Kyst- og havlandet viser bredden i norsk kysthistorie, og finnes også i engelsk utgave. Siden har heftet Riksvei nr. 1 tatt for seg maritim infrastruktur, Ressursar til låns og Den norsk arktiske torsken og verden har lagt vekt på sild og torsk sin betydning for norsk fiskeri- og kysthistorie. Videre formidler heftene Verdens Fraktemenn og Åkeren kan òg være blå sentrale sider ved norsk sjøfartshistorie og fremveksten av havbruksnæringen, to næringer som også i dag utgjør sentrale deler av det kystvendte næringslivet i Norge. Det siste heftet så langt, det syvende i rekken, handler om norsk hvalfangsthistorie, og har fått tittelen Hval, veid, fangst og norske kyster. Her blir hvalfangstens historie fulgt fra de eldste tiders fangst med enkle midler og nyttiggjørelse av strandede hvaler, til den ekspansive utviklingen av industrialisert hvalfangst både ved norskekysten og ved fjerne kyster i Sydishavet, og de konsekvenser dette fikk. Teksten er Jan Erik Ringstads verk, mens Sølvi Vik har vært billedredaktør. Museum Vest har koordinert den tekniske produksjonen og kontakten mellom forfatter og Redaksjonsrådet. Medlemmer i redaksjonsrådet har vært Pål Christensen fra Museum Nord, Jo van der Eyden fra Etatsmuseet for Kystverket, Per G. Norseng fra Norsk Maritimt Museum og Bjørg Christophersen, Anders Haaland og Årstein Svihus fra Museum Vest. Direktoratene og nettverksmuseene håper at de nasjonale rammefortellingene vil være til glede, ettertanke og nytte for alle kystkulturinteresserte, og at de kan bidra til et historisk perspektiv på nåtidens og framtidens utfordringer. Direktoratene og museene tar gjerne imot spørsmål eller synspunkter på prosjektet. Les mer om Fortellinger om kyst-Norge på www.kyst-norge.no. 10. oktober 2011 På østsiden av Larviksfjorden skjærer den lille bukta Rekkevik inn i det kuperte landskapet. På sletta innerst i bukta lå Colin Archers båtbyggeri hvor polarskipet Fram ble bygget. Like bak båtbyggeriet åpner det seg en åtte meter bred kløft som smalner av innover. Da man i 1914 skulle grave en brønn ytterst i denne kløfta, støtte man på noen meget store knokler som man hogg seg gjennom for å få brønnen tilstrekkelig dyp. De avhogde fragmentene ble innsendt til universitetet, hvor man fastslo at det var knokler av grønlandshval. Grønlandshvalen er en av tre hvalarter som lever hele sitt liv i Arktis – de andre to er hvithvalen og narhvalen. Funnstedet lå noe over 40 meter fra strandlinjen, fire, fem kilometer utenfor raet. En analyse av funnet indikerer at hvalen kan ha kjørt seg fast i kløfta da denne lå på ca. 30 meters dyp, og druknet. Klimaet må da ha vært høyarktisk, og dateringen ble satt til ca. 10 000 f. Kr. Hvalen følger mennesket i tid og rom. Det finnes knapt en kyst der mennesker har bodd uten at hval og andre sjøpattedyr har vært del av deres ressursgrunnlag. Fra kysten har man sett hvalens mektige ”blåst” og kraftige bevegelser. Iblant strandet store eksemplarer og ga opphav til mytiske forestillinger og inspirasjon til avbildninger. Hvalen kan altså følges 10-12 000 år tilbake langs våre kyster. Vi skal møte den i noen tekster fra norrøn tid av, diskutere ulike fangstprinsipper og omtale Svend Foyns granatharpun. Fra vår egen kyst skal vi følge fangsten til en rekke felt kloden rundt, især til Antarktis med annekteringer av store landområder i hvalfangstens kjølvann. En rekke aktører fortjener omtale, både investorer, arbeidere, motstandere, forskere, politikere og de som ble igjen hjemme da flåten dro av sted. Målet er at heftet skal bidra til kunnskap om viktige linjer i norsk hvalfangsthistorie.

Menneskenes historie i Antarktis er ikke mer enn noen hundre år gammel. De viktigste kildene til denne historien er ekspedisjonsberetningene – en omfangsrik litteratur som kan leses på mange måter, også fra et kjønnsperspektiv.

This paper describes a method used to model relative wetness for part of the Antarctic Dry Valleys using Geographic Information Systems (GIS) and remote sensing. The model produces a relative index of liquid water availability using variables that influence the volume and distribution of water. Remote sensing using Moderate Resolution Imaging Spectroradiometer (MODIS) images collected over four years is used to calculate an average index of snow cover and this is combined with other water sources such as glaciers and lakes. This water source model is then used to weight a hydrological flow accumulation model that uses slope derived from Light Detection and Ranging (LIDAR) elevation data. The resulting wetness index is validated using three-dimensional visualization and a comparison with a high-resolution Advanced Land Observing Satellite image that shows drainage channels. This research demonstrates that it is possible to produce a wetness model of Antarctica using data that are becoming widely available. Keywords: GIS; water; Antarctica; remote sensing.

We use observations of N2O and mean age to identify realistic transport in models in order to explain their ozone predictions. The results are applied to 15 chemistry climate models (CCMs) participating in the 2010 World Meteorological Organization ozone assessment. Comparison of the observed and simulated N2O, mean age and their compact correlation identifies models with fast or slow circulations and reveals details of model ascent and tropical isolation. This process-oriented diagnostic is more useful than mean age alone because it identifies models with compensating transport deficiencies that produce fortuitous agreement with mean age. The diagnosed model transport behavior is related to a model's ability to produce realistic lower stratosphere (LS) O3 profiles. Models with the greatest tropical transport problems compare poorly with O3 observations. Models with the most realistic LS transport agree more closely with LS observations and each other. We incorporate the results of the chemistry evaluations in the Stratospheric Processes and their Role in Climate (SPARC) CCMVal Report to explain the range of CCM predictions for the return-to-1980 dates for global (60°S–60°N) and Antarctic column ozone. Antarctic O3 return dates are generally correlated with vortex Cly levels, and vortex Cly is generally correlated with the model's circulation, although model Cl chemistry and conservation problems also have a significant effect on return date. In both regions, models with good LS transport and chemistry produce a smaller range of predictions for the return-to-1980 ozone values. This study suggests that the current range of predicted return dates is unnecessarily broad due to identifiable model deficiencies.

The colonization capacity and demographic structure of populations of Deschampsia antarctica and Colobanthus quitensis were studied in different microhabitats between 10 and 147 m a.s.l. on Livingston Island, South Shetland Islands, near the Spanish Antarctic base Juan Carlos I, in February 2002. At the highest site (147 m a.s.l.), mean temperatures were about 1 ºC lower than at sea level. Both species are less common in inland areas and at the highest altitudes only occur at restricted sites that are frequently snow-free in the early austral summer. The diameters of the largest plants (C. quitensis cushions 7-8 cm ; D. antarctica tufts 10-11 cm) in the populations growing at the highest altitudes (110 and 147 m a.s.l.) suggest that these populations were established about 24-28 years ago. The largest diameter plants (Deschampsia 20 cm; Colobanthus 18 cm) were found at the lowest altitudes on deep soil. The presence of numerous seedlings and young individuals on the periphery of populations established several years ago or at recently colonized sites suggests an active process of expansion. There were more emerged seedlings of C. quitensis than of D. antarctica, but the density of established individuals was higher for D. antarctica, suggesting these species have different demographic strategies. Keywords: Antarctic vascular plants; altitude and habitat effect; colonization; population structure.

The horizontal wind data from the standard version of Canadian Middle Atmosphere Model Data Assimilation System (CMAM-DAS) for the years 2006–2008 are analyzed to obtain the global structure and seasonal variability of the semidiurnal tide (SDT) in the mesosphere. The modeled amplitudes and phases of the SDTs at single stations from middle/high northern latitudes are quite similar to those observed by radars. The primary nonmigrating tides identified in both the meridional wind and zonal wind semidiurnal spectra at 88 km include the westward propagating wave numbers s = 1 (SW1), 3 (SW3), 4 (SW4), 6 (SW6), the standing s = 0 (S0), and the eastward propagating s = 2 (SE2). The migrating SDT (SW2) amplitude maxima usually occur at 40°N–60°N during December–February and August–September, and also at 40°S–60°S in April–May, with the dominance of (2, 4) during October–April and (2, 3) and (2, 5) dominance for other months. The CMAM-DAS is quite successful in reproducing the dominance of SW1 in the Antarctic summer mesosphere. The modeled SW1 shows very good overall agreement in both amplitude and phase with wind measurements from UARS High Resolution Doppler Imager and Wind Imaging Interferometer (UARS-HRDI/WINDII) and from TIMED Doppler Interferometer (TIDI). The CMAM-DAS analyses for SW3, SW4, SW6, and S0 are also in reasonable agreement with those determined from the HRDI/WINDII or TIDI wind measurements. This work provides further evidence for the tidal forcing from below.