Polar Research (E-Journal)
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High-Arctic gamasid mites (Acari, Mesostigmata): community composition on Spitsbergen, Svalbard
No full textThis study investigates assemblages of mesostigmatid mites on Spitsbergen, in the Arctic archipelago of Svalbard, Norway. Soil samples were collected from three areas with differing vegetational communities in Adventdalen. The greatest gamasid mite density and species diversity was observed at the location with the richest vegetation cover, Dryas octapetala heath, where 10 species were collected and there was a mean total gamasid mite density of 1,000 individuals per m2. The vegetation-poor saline meadow site revealed five species and had a mean total gamasid mite density of 130 individuals per m². The floristically more diverse Luzula tundra site yielded four species and had a density of 270 individuals per m². The most frequently found species were Zercon forsslundi, Arctoseius haarlovi and A. weberi. Results indicate that even in High-Arctic regions, where species diversity is less than at lower latitudes, there is specialization amongst the gamasid mite community depending on local environmental conditions. Apart from isolated checklists, only sporadic information concerning the ecology of High-Arctic gamasid mites is available. Many of the gamasid mites reported from Svalbard are relatively rare.Keywords: mites, Acari, Mesostigmata, Arctoseius, Zercon, Spitsbergen (Published: 29 August 2011) Citation: Polar Research 2011, 30, 8311, DOI: 10.3402/polar.v30i0.831
Variability of nutrient and thermal structure in surface waters between New Zealand and Antarctica, October 2004-January 2005
No full textWe describe the upper ocean thermal structure and surface nutrient concentrations between New Zealand and Antarctica along five transects that cross the Subantarctic Front, the Polar Front and the southern Antarctic Circumpolar Current front. The surface water thermal structure is coupled with variations in surface nutrient concentrations, making water masses identifiable by both temperature and nutrient ranges. In particular, a strong latitudinal gradient in orthosilicate concentration is centred at the Polar Front. On the earlier sections, which extend south-west from the Campbell Plateau, orthosilicate increases sharply southward from 10-15 to 50-55µmol l-1, between 58°S and 60°S, while surface temperature drops from 7°C to 2°C. Nitrate increases more regularly toward the south, with concentrations ranging from 10-12µmol l-1 at 54°S to 25-30µmol l-1 at 66°S. The same features are observed during the later transects between New Zealand and the Ross Sea, but the sharp silica and surface temperature gradients are shifted between 60°S and 64°S. Both temporal and spatial factors may influence the observed variability. The January transect suggests an uptake of silica, orthophosphate and nitrate between 63°S and 70°S over the intervening month, with an average depletion near 37%, 44% and 29%, respectively. An N/P apparent drawdown ratio of 8.8±4.1 and an Si/N apparent drawdown ratio >1 suggests this depletion results from a seasonal diatom bloom. A southward movement of the oceanic fronts between New Zealand and the Ross Sea relative to prior measurements is consistent with reports of recent warming and changes in the Antarctic Circumpolar Current.Keywords: Southern Ocean, nutrients, silica belt, Antarctic Circumpolar Current, expendable bathythermograph (Published: 13 April 2011) Citation: Polar Research 2011, 30, 7064, DOI: 10.3402/polar.v30i0.706
Thousand years of winter surface air temperature variations in Svalbard and northern Norway reconstructed from ice core data
No full textTwo isotopic ice core records from western Svalbard are calibrated to reconstruct more than 1000 years of past winter surface air temperature variations in Longyearbyen, Svalbard, and Vardø, northern Norway. Analysis of the derived reconstructions suggests that the climate evolution of the last millennium in these study areas comprises three major sub-periods. The cooling stage in Svalbard (ca. 800-1800) is characterized by a progressive winter cooling of approximately 0.9°C century-1 (0.3°C century-1 for Vardø) and a lack of distinct signs of abrupt climate transitions. This makes it difficult to associate the onset of the Little Ice Age in Svalbard with any particular time period. During the 1800s, which according to our results was the coldest century in Svalbard, the winter cooling associated with the Little Ice Age was on the order of 4°C (1.3°C for Vardø) compared to the 1900s. The rapid warming that commenced at the beginning of the 20th century was accompanied by a parallel decline in sea-ice extent in the study area. However, both the reconstructed winter temperatures as well as indirect indicators of summer temperatures suggest the Medieval period before the 1200s was at least as warm as at the end of the 1990s in Svalbard.Keywords: Palaeoclimatology; late Holocene; winter temperature; regional climate; stable water isotopes; palaeoreconstruction(Published: 22 July 2011)Citation: Polar Research 2011, 30, 7379, DOI: 10.3402/polar.v30i0.737
Response of Eyjafjallajökull, Torfajökull and Tindfjallajökull ice caps in Iceland to regional warming, deduced by remote sensing
No full textWe assess the volume change and mass balance of three ice caps in southern Iceland for two periods, 1979/1984 to 1998 and 1998 to 2004, by comparing digital elevation models (DEMs). The ice caps are Eyjafjallajökull (ca. 81 km²), Tindfjallajökull (ca. 15 km²) and Torfajökull (ca. 14 km²). The DEMs were compiled using aerial photographs from 1979 to 1984, airborne Synthetic Aperture Radar (SAR) images obtained in 1998 and two image pairs from the SPOT 5 satellite’s high-resolution stereoscopic (HRS) instrument acquired in 2004. The ice-free part of the accurate DEM from 1998 was used as a reference map for co-registration and correction of the vertical offset of the other DEMs. The average specific mass balance was estimated from the mean elevation difference between glaciated areas of the DEMs. The glacier mass balance declined significantly between the two periods: from -0.2 to 0.2 m yr-1 w. eq. during the earlier period (1980s through 1998) to -1.8 to -1.5 m yr-1 w. eq. for the more recent period (1998-2004). The declining mass balance is consistent with increased temperature over the two periods. The low mass balance and the small accumulation area ratio of Tindfjallajökull and Torfajökull indicate that they will disappear if the present-day climate continues. The future lowering rate of Eyjafjallajökull will, however, be influenced by the 2010 subglacial eruption in the Eyjafjallajökull volcano.Keywords: Remote sensing, glacier mass balance, regional warming, Eyjafjallajökull, Torfajökull, Tindfjallajökull(Published: 20 July 2011)Citation: Polar Research 2011, 30, 7282, DOI: 10.3402/polar.v30i0.728
Perspective: The fostering of cross-disciplinary science as a result of the IPY: ‘‘connectivity’’ created by the Canada Three Oceans project
No full textThe fourth International Polar Year (IPY), which ended in March 2009, represented a ca. 50% increase in the funding of polar science, a major expansion of the observing effort across polar and subpolar seas, the deployment of a wide range of new and complex observing techniques and a gratifying new degree of international collaboration in their use. As a result, the IPY has revolutionized our polar data sets to provide our first real glimpse of the ocean-atmosphere-cryosphere operating as a complete system. Here we focus on one particular aspect of the emerging results - the ‘‘connectivities’’ that may develop between individual research projects over time, developing the complexity of our understanding in real if unexpected ways as new findings emerge, ramify and mesh within projects or between them. For simplicity, we illustrate this valuable but unpredictable process by using one particular Arctic-sub-Arctic project - Canada Three Oceans - as our initial reference point and attempting to trace out a small subset of its interconnections across space, time, projects and disciplines.Keywords: International Polar Year; connectivity; downscaling; northern seas; climate change; international collaboration(Published: 29 December 2011)Citation: Polar Research 2011, 30, 10908, DOI: 10.3402/polar.v30i0.1090
Validating satellite derived and modelled sea-ice drift in the Laptev Sea with in situ measurements from the winter of 2007/08
No full textA correct representation of the ice movement in an Arctic sea-ice-ocean coupled model is essential for a realistic sea-ice and ocean simulation. The aim of this study is to validate the observational and simulated sea-ice drift for the Laptev Sea Shelf region with in situ measurements from the winter of 2007/08. Several satellite remote-sensing data sets are first compared to mooring measurements and afterwards to the sea-ice drift simulated by the coupled sea-ice-ocean model. The different satellite products have a correlation to the in situ data ranging from 0.56 to 0.86. The correlations of sea-ice direction or individual drift vector components between the in situ data and the observations are high, about 0.8. Similar correlations are achieved by the model simulations. The sea-ice drift speed derived from the model and from some satellite products have only moderate correlations of about 0.6 to the in situ record. The standard errors for the satellite products and model simulations drift components are similar to the errors of the satellite products in the central Arctic and are about 0.03 m/s. The fast-ice parameterization implementation in the model was also successfully tested for its influence on the sea-ice drift. In contrast to the satellite products, the model drift simulations have a full temporal and spatial coverage and results are reliable enough to use as sea-ice drift estimates on the Laptev Sea Shelf.Keywords: Shelf seas; sea-ice drift; sea-ice-ocean coupled model; acoustic Doppler current profiler; fast ice(Published: 5 August 2011)Citation: Polar Research 2011, 30, 7218, DOI: 10.3402/polar.v30i0.721
The impact of a thermodynamic sea-ice module in the COSMO numerical weather prediction model on simulations for the Laptev Sea, Siberian Arctic
No full textPrevious versions of the Consortium for Small-scale Modelling (COSMO) numerical weather prediction model have used a constant sea-ice surface temperature, but observations show a high degree of variability on sub-daily timescales. To account for this, we have implemented a thermodynamic sea-ice module in COSMO and performed simulations at a resolution of 15 km and 5 km for the Laptev Sea area in April 2008. Temporal and spatial variability of surface and 2-m air temperature are verified by four automatic weather stations deployed along the edge of the western New Siberian polynya during the Transdrift XIII-2 expedition and by surface temperature charts derived from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data. A remarkable agreement between the new model results and these observations demonstrates that the implemented sea-ice module can be applied for short-range simulations. Prescribing the polynya areas daily, our COSMO simulations provide a high-resolution and high-quality atmospheric data set for the Laptev Sea for the period 14-30 April 2008. Based on this data set, we derive a mean total sea-ice production rate of 0.53 km3/day for all Laptev Sea polynyas under the assumption that the polynyas are ice-free and a rate of 0.30 km3/day if a 10-cm-thin ice layer is assumed. Our results indicate that ice production in Laptev Sea polynyas has been overestimated in previous studies.Keywords: Laptev Sea; polynya; mesoscale modelling(Published: 12 May 2011)Citation: Polar Research 2011, 30, 6334, DOI: 10.3402/polar.v30i0.633
Review of Biology of polar benthic algae, edited by Christian Wiencke
No full textThis impressive book summarizes international research on Arctic and Antarctic benthic algae spanning more than three decades. Fifteen chapters and 38 contributors are a clear indication for a broad range of topics discussed in this book. The editor is a leading luminary in this area and has capably orchestrated the authors’ intelligent contributions to form a comprehensive view of this important topic.
(Published: 14 June 2011)
Citation: Polar Research 2011, 30, 7315, DOI: 10.3402/polar.v30i0.731
From the institute’s Photo Library
No full textBjarne Lorentzen spreads good cheer during the 1951 Christmas celebrations at the base of the Norwegian-British-Swedish Antarctic Expedition (1949-1952). The base, known as Maudheim, was located on the floating ice shelf off Dronning Maud Land.(Published: 29 December 2011)Citation: Polar Research 2011, 30, 15942, DOI: 10.3402/polar.v30i0.1594
Greenland sharks (Somniosus microcephalus) scavenge offal from minke (Balaenoptera acutorostrata) whaling operations in Svalbard (Norway)
No full textMinke whale (Balaenoptera acutorostrata) tissue (mainly blubber) was found in the gastrointestinal tracks of Greenland sharks (Somniosus microcephalus) collected in Kongsfjorden, Svalbard, Norway. In order to determine whether the sharks were actively hunting the whales, finding naturally dead whales or consuming offal from whaling, we checked the genetic identity of the whale tissue found in the sharks against the DNA register for minke whales taken in Norwegian whaling operations. All of the minke whale samples from the sharks that had DNA of sufficient quality to perform individual identifications were traceable to the whaling DNA register. During whaling operations, the blubber is stripped from the carcass and thrown overboard. The blubber strips float on the surface and are available for surface-feeding predators. This study revealed that Greenland sharks are scavenging this material; additionally, it demonstrates the capacity of this ‘benthic-feeding’ shark to utilize the whole water column for foraging. Keywords: Carrion; diet; DNA register; Greenland shark; minke whale (Published: 30 June 2011) Citation: Polar Research 2011, 30, 7342, DOI: 10.3402/polar.v30i0.734