Polar Research (E-Journal)
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Summer foraging behaviour of shallow-diving seabirds and distribution of their prey, Arctic cod (Boreogadus saida), in the Canadian Arctic
No full textProductive areas in the Canadian Arctic seasonally provide top predators with accessible and often predictable sources of energy. Arctic cod (Boreogadus saida) aggregate in shallow bays during the summer and are exploited by seabirds and marine mammals. Information concerning how prey is presented to predatory seabirds, and the cues seabirds use to optimize foraging potential, is limited. Hydroacoustic surveys were completed in Allen Bay, Nunavut, to determine the presence, density, abundance, and depth of Arctic cod schools in relation to shallow-diving seabirds. Schools were also documented using standardized protocols to examine the influence of environmental variables, such as wind, ice, tidal states and seabird behaviour. The presence of schools was a significant predictor of the distribution of northern fulmars (Fulmarus glacialis) but not black-legged kittiwakes (Rissa tridactyla). Glaucous gulls (Larus hyperboreus) associated with northern fulmars are likely optimizing chances of stealing Arctic cod. The density, size and depth of schools did not significantly affect the distribution of the seabirds. We speculate that Arctic cod from demersal schools separate to feed at the surface in satellite schools (groups of dispersed fish), thus reducing competition but increasing the risk of predation.Keywords: Satellite schools; schooling; predators; northern fulmar; black-legged kittiwake; glaucous gull(Published: 3 September 2012)Citation: Polar Research 2012, 31, 15894, http://dx.doi.org/10.3402/polar.v31i0.1589
A new DEM of the Austfonna ice cap by combining differential SAR interferometry with ICESat laser altimetry
No full textWe present a new digital elevation model (DEM) of the Austfonna ice cap in the Svalbard Archipelago, Norwegian Arctic. Previous DEMs derived from synthetic aperture radar (SAR) and optical shape-from-shading have been tied to airborne radio echo-sounding surface profiles from 1983 which contain an elevation-dependent bias of up to several tens of metres compared with recent elevation data. The new and freely available DEM is constructed purely from spaceborne remote sensing data using differential SAR interferometry (DInSAR) in combination with ICESat laser altimetry. Interferograms were generated from pairs of SAR scenes from the one-day repeat tandem phase of the European Remote Sensing Satellites 1/2 (ERS-1/2) in 1996. ICESat elevations from winter 200608 were used as ground control points to refine the interferometric baseline. The resulting DEM is validated against the same ground control points and independent surface elevation profiles from Global Navigation Satellite Systems (GNSS) and airborne laser altimetry, yielding root mean square (RMS) errors of about 10 m in all cases. This quality is sufficient for most glaciological applications, and the new DEM will be a baseline data set for ongoing and future research at Austfonna. The technique of combining satellite DInSAR with high-resolution satellite altimetry for DEM generation might also be a good solution in other glacier regions with similar characteristics, especially when data from TanDEM-X and CryoSat-2 become available.Keywords: SAR; ICESat; DEM; Austfonna; ice cap; glacier.(Published: 16 May 2012)Citation: Polar Research 2012, 31, 18460, http://dx.doi.org/10.3402/polar.v31i0.1846
Review of Field techniques for sea ice research, by Hajo Eicken, Rolf Gradinger, Maya Salganek, Kunio Shirasawa, Don Perovich & Matti Leppäranta
No full textWith the rapid decrease of the summer sea-ice cover in the Arctic, sea ice and the work of sea-ice researchers have been regularly in the spotlight of media and public attention in recent years. This book is a timely attempt to create a set of guidelines for the most common techniques for field measurements of sea-ice properties, filling a gap in the recently published sea-ice literature. Led by Hajo Eicken, the editors bring together 29 contributors, a group that mirrors in its composition the collaborative, international and interdisciplinary nature of sea-ice research and forms the base for the wide range of topics.
(Published: 24 January 2012)
Citation: Polar Research 2012, 31, 16813, DOI: 10.3402/polar.v31i0.1681
Sea-ice cover anomalies in the Arctic Basin associated with atmospheric variability from multi-decadal trends to intermittent quasi-biennial oscillations
No full textArctic Ocean sea ice has been diminishing since 1970, as shown by National Snow and Ice Data Center data. In addition to decadal variability, low ice anomalies in the Pacific-Siberian region have been occurring at shorter timescales. The influence of the widely-known Northern Annular Mode (NAM) occurs across all seasons. In this study, empirical orthogonal function (EOF) analysis was applied to sea-level pressure in National Centers for Environmental Prediction Reanalysis data for 1960-2007, showing the NAM to be the leading mode of variability and the Arctic Dipole Mode (ADM) to be the second leading mode. The ADM changes markedly across seasons. In autumn-winter, it has a pole over Siberia and a pole over Greenland, at opposite signs at a several-year scale, whereas the spring-summer ADM (ADMSS) has a pole over Europe and a pole over Canada. In the 1980s, the most influential mode shifted from the NAM to the ADM, when the Pacific sector had low ice cover at a 1-year lag from the positive ADM, which was marked by low pressure over Siberia. In years when the ADMSS was pronounced, it was responsible for distinct ice variability over the East Siberian-Laptev seas. The frequency separation in this study identified the contributions of the ADM and ADMSS. Effects of the latter are difficult to predict since it is intermittent and changes its sign biennially. The ADM and ADMSS should be closely watched in relation to the ongoing ice reduction in the Pacific-Siberian region.Keywords: Sea ice; sea-level pressure; Arctic interannual variability; EOF analysis(Published: 12 June 2012)This article repeats an error in the list of authors of an article published in the Journal of Oceanography. Please see the erratum issued by the Journal of Oceanography http://www.terrapub.co.jp/journals/JO/abstract/2010/6606/66060885.htmlCitation: Polar Research 2012, 31, 18690, http://dx.doi.org/10.3402/polar.v31i0.1869
Svalbard reindeer population size and trends in four sub-areas of Edgeøya
No full textIn summer 2006 Svalbard reindeer (Rangifer tarandus platyrhynchus) in southwestern Edgeøya (Plurdalen, Grunnlinjesletta, Siegelfjellet and Burmeisterfjellet) showed a low population (181 animals) and recruitment rate, in terms of both calves (9.4%) and yearlings (1.2%). The low recruitment rates were not accompanied by high winter mortality: of only five carcasses found, none were calves born in 2005. A comparison with survey data from 1969 in a restricted part of the study area (Plurdalen and Grunnlinjesletta) shows a consistently low recruitment rate since 1975, indicating a stable or slowly decreasing population.Keywords Edgeøya; population regulation; recruitment rates; Svalbard reindeer; winter mortality; Rangifer tarandus platyrhynchus (Published: 15 May 2012)Citation: Polar Research 2012, 31, 11089, http://dx.doi.org/10.3402/polar.v31i0.1108
Perspective: Managing visitor sites in Svalbard: from a precautionary approach towards knowledge-based management
No full textIncreased tourism in the Arctic calls for more knowledge to meet management challenges. This paper reviews existing knowledge of the effects of human use on vegetation, fauna and cultural heritage in Svalbard, and it addresses the need for site-specific knowledge for improved management. This paper draws upon scientific studies, knowledge held by management authorities and local people, the Governor’s database on visitors and visited sites and our own data from landing sites we visited. There is a certain level of basic knowledge available, allowing us to roughly grade the vulnerability of sites. However, there is a thorough lack of site-specific data related to the management of single locations or groups of similar locations. Future research needs to address specific on-site challenges in the management of visitor sites. Relevant management models and measures are discussed.We contend that a shift away from a blanket application of the precautionary principle and towards a more integrated, site-specific and evidence-based management plan will contribute to more trusted and reliable, and thereby acceptable among stakeholders, decisions in the management of growing tourism activity in Svalbard.Keywords: Arctic; resource management; planning; tourism(Published: 4 May 2012)Citation: Polar Research 2012, 31, 18432, http://dx.doi.org/10.3402/polar.v31i0.1843
Dolerites of Svalbard, north-west Barents Sea Shelf: age, tectonic setting and significance for geotectonic interpretation of the High-Arctic Large Igneous Province
No full textThe dolerites of Svalbard are mineralogically and geochemically homogeneous with geochemical features typical of continental within-plate tholeiites. Their geochemistry is similar to tholeiites belonging to a bimodal suite defined as the High-Arctic Large Igneous Province (HALIP). K-Ar dating of numerous dolerites sampled from many locations across Svalbard define a narrow time span of this magmatism from 125.5±3.6 to 78.3±2.6 Mya. Discrete peaks of intensive activity occurred at 115.3, 100.8, 91.3 and 78.5 Mya corresponding to breakup of the continental crust and formation of an initial rift as a result of mantle plume activity, located in the southern part of the Alpha Ridge; magmatic activity related to spreading along the Alpha Ridge that led to the development of the initial oceanic crust and continuation of spreading along the Alpha Ridge and termination of magmatic activity related to HALIP (last two peaks at 91.3 and 78.5 Mya).Keywords: Dolerite; geochemistry; petrogenesis; K-Ar whole rock ages; Svalbard; Cretaceous(Published: 3 August 2011)Citation: Polar Research 2011, 30, 7306, DOI: 10.3402/polar.v30i0.730
Review of Antarctic climate change and the environment edited by John Turner et al.
No full textThis impressive report from the Scientific Committee on Antarctic Research (SCAR) covers nearly 400 pages of text with more than 100 additional pages of references. Under the clearly very able leadership of John Turner of the British Antarctic Survey, the nine editors have coordinated more than 100 contributors to produce a comprehensive review of our knowledge of Antarctica’s climate up to 2007.(Published: 21 February 2011)Citation: Polar Research 2011, 30, 5985, DOI: 10.3402/polar.v30i0.598
Spatio-temporal variability of polynya dynamics and ice production in the Laptev Sea between the winters of 1979/80 and 2007/08
No full textPolynyas in the Laptev Sea are examined with respect to recurrence and interannual wintertime ice production.We use a polynya classification method based on passive microwave satellite data to derive daily polynya area from long-term sea-ice concentrations. This provides insight into the spatial and temporal variability of open-water and thin-ice regions on the Laptev Sea Shelf. Using thermal infrared satellite data to derive an empirical thin-ice distribution within the thickness range from 0 to 20 cm, we calculate daily average surface heat loss and the resulting wintertime ice formation within the Laptev Sea polynyas between 1979 and 2008 using reanalysis data supplied by the National Centers for Environmental Prediction, USA, as atmospheric forcing. Results indicate that previous studies significantly overestimate the contribution of polynyas to the ice production in the Laptev Sea. Average wintertime ice production in polynyas amounts to approximately 55 km3 ± 27% and is mostly determined by the polynya area, wind speed and associated large-scale circulation patterns. No trend in ice production could be detected in the period from 1979/80 to 2007/08.Keywords: Polynya dynamics; ice production; sea-ice remote sensing(Published: 12 May 2011)Citation: Polar Research 2011, 30, 5971, doi: 10.3402/polar.v30i0.597
Spatial modelling of wetness for the Antarctic Dry Valleys
No full textThis 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 Citation: Polar Research 2011, 30, 6330, DOI: 10.3402/polar.v30i0.633