| 1. |
- Beaudon, Emelie, et al.
(author)
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Lomonosovfonna and Holtedahlfonna ice cores reveal east west disparities of the Spitsbergen environment since AD 1700
- 2013
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In: Journal of Glaciology. - 0022-1430 .- 1727-5652. ; 59:218, s. 1069-1083
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Journal article (peer-reviewed)abstract
- An ice core extracted from Holtedahlfonna ice cap, western Spitsbergen, record spanning the period 1700–2005, was analyzed for major ions. The leading empirical orthogonal function (EOF) component is correlated with an index of summer melt (log([Na + ]/[Mg 2+ ]) from 1850 and shows that almost 50% of the variance can be attributed to seasonal melting since the beginning of the industrial revolution. The Holtedahlfonna d 18 O value is less negative than in the more easterly Lomonosovfonna ice core, suggesting that moist air masses originate from a closer source, most likely the Greenland Sea. During the Little Ice Age the lower methanesulfonic acid (MSA) concentration and MSA non-sea-salt sulfate fraction are consistent with the Greenland Sea as the main source for biogenic ions in the ice cores. Both the melt index and the MSA fraction suggest that the early decades of the 18th century may have exhibited the coldest summers of the last 300 years in Svalbard. Ammonium concentrations rise from 1880, which may result from the warming of the Greenland Sea or from zonal differences in atmospheric pollution transport over Svalbard. During winter, neutralized aerosols are trapped within the tropospheric inversion layer, which is usually weaker over open seas than over sea ice, placing Holtedahlfonna within the inversion more frequently than Lomonosovfonna.
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| 2. |
- Beaudon, Emilie, et al.
(author)
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Spatial and temporal variability of net accumulation from shallow cores from Vestfonna ice cap (Nordaustlandet, Svalbard)
- 2011
-
In: Geografiska Annaler. Series A, Physical Geography. - : Informa UK Limited. - 0435-3676 .- 1468-0459. ; 93:4, s. 287-299
-
Journal article (peer-reviewed)abstract
- We analyse ice cores from Vestfonna ice cap (Nordaustlandet, Svalbard). Oxygen isotopic measurements were made on three firn cores (6.0, 11.0 and 15.5 m deep) from the two highest summits of the glacier located on the SW–NE and NW–SE central ridges. Sub-annual δ18O cycles were preserved and could be counted visually in the uppermost parts of the cores, but deeper layers were affected by post-depositional smoothing. A pronounced δ18O minimum was found near the bottom of the three cores. We consider candidates for this δ18O signal to be a valuable reference horizon since it is also seen elsewhere in Nordaustlandet. We attribute it to isotopically depleted snow precipitation, which NCEP/NCAR reanalysis shows was unusual for Vestfonna, and came from northerly air during the cold winter of 1994/95. Finding the 1994/95 time marker allows establishment of a precise depth/age scale for the three cores. The derived annual accumulation rates indirectly fill a geographical gap in mass balance measurements and thus provide information on spatial and temporal variability of precipitation over the glacier for the period spanned by the cores (1992–2009). Comparing records at the two locations also reveals that the snow net accumulation at the easternmost part of Vestfonna was only half of that in the western part over the last 17 years.
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| 3. |
- Braun, Matthias, et al.
(author)
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Changes of glacial front positions of Vestfonna (Nordaustlandet, Svalbard)
- 2011
-
In: Geografiska Annaler. Series A, Physical Geography. - : Informa UK Limited. - 0435-3676 .- 1468-0459. ; 93:4, s. 301-310
-
Journal article (peer-reviewed)abstract
- Glaciers in Svalbard have shown considerable mass loss in recent years with a reported acceleration in the western and southern parts of the archipelago. However, for the ice cap Vestfonna, in northeastern Svalbard, climatic mass balance modelling has suggested almost balanced conditions over a period of nine years (2000–2009). A slightly positive geodetic mass balance (1990–2005) has been reported from a comparison of laser altimetry to older DEMs. A heterogeneous situation has been depicted for the various catchments, and hence changes in glacier extent can reveal additional information of glacier status, in particular when dealing with surge-type glaciers. We analysed a 34-year data record of multi-spectral satellite imagery in order to study changes in glacier frontal positions of the ice cap Vestfonna. A consistent pattern of almost steady retreat of the southern and north-eastern outlet glaciers of the ice cap is observed while Franklinbreen, the only major outlet glacier draining towards the north-west shows re-advance. This is consistent with an observed speed up and potential upcoming surge of this outlet. The glacier retreat on the southern coast also agrees with ICESat elevation change measurements. However, due to the glacier response time no direct relations between frontal retreat and surface mass balance can be drawn from the short observation period. The heterogeneous pattern of changes with on-going dynamic adjustments in some areas make the ice cap Vestfonna an ideal test site for future monitoring activities including novel techniques like differential interferometry from bi-static SAR systems.
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| 4. |
- Callaghan, Terry, et al.
(author)
-
Multi-Decadal Changes in Tundra Environments and Ecosystems : Synthesis of the International Polar Year-Back to the Future Project (IPY-BTF)
- 2011
-
In: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 40:6, s. 705-716
-
Journal article (peer-reviewed)abstract
- Understanding the responses of tundra systemsto global change has global implications. Most tundraregions lack sustained environmental monitoring and oneof the only ways to document multi-decadal change is toresample historic research sites. The International PolarYear (IPY) provided a unique opportunity for such researchthrough the Back to the Future (BTF) project (IPY project#512). This article synthesizes the results from 13 paperswithin this Ambio Special Issue. Abiotic changes includeglacial recession in the Altai Mountains, Russia; increasedsnow depth and hardness, permafrost warming, andincreased growing season length in sub-arctic Sweden;drying of ponds in Greenland; increased nutrient availabilityin Alaskan tundra ponds, and warming at mostlocations studied. Biotic changes ranged from relativelyminor plant community change at two sites in Greenland tomoderate change in the Yukon, and to dramatic increasesin shrub and tree density on Herschel Island, and in subarcticSweden. The population of geese tripled at one sitein northeast Greenland where biomass in non-grazed plotsdoubled. A model parameterized using results from a BTFstudy forecasts substantial declines in all snowbeds andincreases in shrub tundra on Niwot Ridge, Colorado overthe next century. In general, results support and provideimproved capacities for validating experimental manipulation,remote sensing, and modeling studies.
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| 5. |
- Charalampidis, Charalampos, 1983-
(author)
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Climatology and firn processes in the lower accumulation area of the Greenland ice sheet
- 2016
-
Doctoral thesis (other academic/artistic)abstract
- The Greenland ice sheet is the largest Northern Hemisphere store of fresh water, and it is responding rapidly to the warming climate. In situ observations document the changing ice sheet properties in the lower accumulation area, Southwest Greenland. Firn densities from 1840 meters above sea level retrieved in May 2012 revealed the existence of a 5.5-meter-thick, near-surface ice layer in response to the recent increased melt and refreezing in firn. As a consequence, vertical meltwater percolation in the extreme summer 2012 was inefficient, resulting in surface runoff. Meltwater percolated and refroze at six meters depth only after the end of the melt season. This prolonged autumn refreezing under the newly accumulated snowpack resulted in unprecedented firn warming with temperature at ten meters depth increased by more than four degrees Celsius. Simulations confirm that meltwater reached nine meters depth at most. The refrozen meltwater was estimated at 0.23 meters water equivalent, amounting to 25 % of the total 2012 ablation.A surface energy balance model was used to evaluate the seasonal and interannual variability of all surface energy fluxes at that elevation in the years 2009 to 2013. Due to the meltwater presence at the surface in 2012, the summer-averaged albedo was significantly reduced (0.71 in 2012; typically 0.78). A sensitivity analysis revealed that 71 % of the subsequent additional solar radiation in 2012 was used for melt, corresponding to 36 % of the total 2012 surface lowering. This interplay between melt and firn properties highlights that the lower accumulation area of the Greenland ice sheet will be responding rapidly in a warming climate.
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| 6. |
- Claremar, Björn, et al.
(author)
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Applying a Mesoscale Atmospheric Model to Svalbard Glaciers
- 2012
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In: Advances in Meteorology. - : Hindawi Publishing Corporation. - 1687-9309 .- 1687-9317. ; , s. 321649-
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Journal article (peer-reviewed)abstract
- The mesoscale atmospheric model WRF is used over three Svalbard glaciers. The simulations are done with a setup of the model corresponding to the state-of-the-art model for polar conditions, Polar WRF, and it was validated using surface observations. The ERA-Interim reanalysis was used for boundary forcing and the model was used with three nested smaller domains, 24 and 8 km, and 2.7 km resolution. The model was used for a two-year period as well as for a more detailed study using 3 summer and winter months. In addition sensitivity tests using finer horizontal and vertical resolution in the boundary layer and using different physics schemes were performed. Temperature and incoming short- and long-wave radiation were skillfully simulated, with lower agreement between measured and modelled wind speed. Increased vertical resolution improved the frequency distributions of the wind speed and the temperature. The choice of different physics schemes only slightly changed the model results. The polar-optimized microphysics scheme outperformed a slightly simpler microphysics scheme, but the two alternative and more sophisticated PBL schemes improved the model score. A PBL scheme developed for very stable stratifications (QNSE) proved to be better in the winter.
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| 7. |
- Clemenzi, Ilaria, et al.
(author)
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Impact of snow distribution modelling for runoff predictions
- 2023
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In: Nordic Hydrology. - : IWA Publishing. - 0029-1277 .- 1996-9694. ; 54:5, s. 633-647
-
Journal article (peer-reviewed)abstract
- Snow in the mountains is essential for the water cycle in cold regions. The complexity of the snow processes in such an environment makes it challenging for accurate snow and runoff predictions. Various snow modelling approaches have been developed, especially to improve snow predictions. In this study, we compared the ability to improve runoff predictions in the Överuman Catchment, Northern Sweden, using different parametric representations of snow distribution. They included a temperature-based method, a snowfall distribution (SF) function based on wind characteristics and a snow depletion curve (DC). Moreover, we assessed the benefit of using distributed snow observations in addition to runoff in the hydrological model calibration. We found that models with the SF function based on wind characteristics better predicted the snow water equivalent (SWE) close to the peak of accumulation than models without this function. For runoff predictions, models with the SF function and the DC showed good performances (median Nash–Sutcliffe efficiency equal to 0.71). Despite differences among the calibration criteria for the different snow process representations, snow observations in model calibration added values for SWE and runoff predictions.
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| 8. |
- Den Ouden, M. A. G., et al.
(author)
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Stand-alone single-frequency GPS ice velocity observations on Nordenskiöldbreen, Svalbard
- 2010
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In: The Cryosphere. - : Copernicus GmbH. - 1994-0416 .- 1994-0424. ; 4:4, s. 593-604
-
Journal article (peer-reviewed)abstract
- Precise measurements of ice-flow velocities are necessary for a proper understanding of the dynamics of glaciers and their response to climate change. We use stand-alone single-frequency GPS receivers for this purpose. They are designed to operate unattended for 1–3 years, allowing uninterrupted measurements for long periods with hourly temporal resolution. We present the system and illustrate its functioning using data from 9 GPS receivers deployed on Nordenskiöldbreen, Svalbard, for the period 2006–2009. The accuracy of the receivers is 1.62 m based on the standard deviation in the average location of a stationary reference station (NBRef). Both the location of NBRef and the observed flow velocities agree within one standard deviation with DGPS measurements. Periodicity (6, 8, 12, 24 h) in the NBRef data is largely explained by the atmospheric, mainly ionospheric, influence on the GPS signal. A (weighed) running-average on the observed locations significantly reduces the standard deviation and removes high frequency periodicities, but also reduces the temporal resolution. Results show annual average velocities varying between 40 and 55 m yr−1 at stations on the central flow-line. On weekly to monthly time-scales we observe a peak in the flow velocities (from 60 to 90 m yr−1) at the beginning of July related to increased melt-rates. No significant lag is observed between the timing of the maximum speed between different stations. This is likely due to the limited temporal resolution after averaging in combination with the relatively small distance (max. ±13 km) between the stations.
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| 9. |
- Divine, Dmitri, et al.
(author)
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Thousand years of winter surface air temperature variations in Svalbard and northern Norway reconstructed from ice-core data
- 2011
-
In: Polar Research. - : Norwegian Polar Institute. - 0800-0395 .- 1751-8369. ; 30, s. 7379-
-
Journal article (peer-reviewed)abstract
- Two 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 Vardo, 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 degrees C century(-1) (0.38 degrees C century(-1) for Vardo) 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 degrees C (1.3 degrees C for Vardo) 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.
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| 10. |
- Divine, D. V., et al.
(author)
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Modelling the regional climate and isotopic composition of Svalbard precipitation using REMOiso : a comparison with available GNIP and ice core data
- 2011
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In: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 25:24, s. 3748-3759
-
Journal article (peer-reviewed)abstract
- Simulations of a regional (approx. 50 km resolution) circulation model REMOiso with embedded stable water isotope module covering the period 1958-2001 are compared with the two instrumental climate and four isotope series (d18O) from western Svalbard. We examine the data from ice cores drilled on Svalbard ice caps in 1997 (Lomonosovfonna, 1250 m asl) and 2005 (Holtedahlfonna, 1150 m asl) and the GNIP series from Ny-angstrom lesund and Isfjord Radio. The surface air temperature (SAT) and precipitation data from Longyearbyen and Ny-angstrom lesund are used to assess the skill of the model in reproducing the local climate. The model successfully captures the climate variations on the daily to multidecadal times scales although it tends to systematically underestimate the winter SAT. Analysis suggests that REMOiso performs better at simulating isotope compositions of precipitation in the winter than summer. The simulated and measured Holtedahlfonna d18O series agree reasonably well, whereas no significant correlation has been observed between the modelled and measured Lomonosovfonna ice core isotopic series. It is shown that sporadic nature as well as variability in the amount inherent in precipitation process potentially limits the accuracy of the past SAT reconstruction from the ice core data. This effect in the study area is, however, diminished by the role of other factors controlling d18O in precipitation, most likely sea ice extent, which is directly related with the SAT anomalies.
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| 11. |
- Grinsted, Aslak, et al.
(author)
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Svalbard summer melting, continentality, and sea ice extent from the Lomonosovfonna ice core
- 2006
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In: Journal of Geophysical Research. - : AGU. ; 111, s. D07110-
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Journal article (peer-reviewed)abstract
- We develop a continentality proxy (1600–1930) based on amplitudes of the annual signal in oxygen isotopes in an ice core. We show via modeling that by using 5 and 15 year average amplitudes the effects of diffusion and varying layer thickness can be minimized, such that amplitudes then reflect real seasonal changes in δ18O under the influence of melt. A model of chemical fractionation in ice based on differing elution rates for pairs of ions is developed as a proxy for summer melt (1130–1990). The best pairs are sodium with magnesium and potassium with chloride. The continentality and melt proxies are validated against twentieth-century instrumental records and longer historical climate proxies. In addition to summer temperature, the melt proxy also appears to reflect sea ice extent, likely as a result of sodium chloride fractionation in the oceanic sea ice margin source area that is dependent on winter temperatures. We show that the climate history they depict is consistent with what we see from isotopic paleothermometry. Continentality was greatest during the Little Ice Age but decreased around 1870, 20–30 years before the rise in temperatures indicated by the δ18O profile. The degree of summer melt was significantly larger during the period 1130–1300 than in the 1990s.
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| 12. |
- Hedfors, Jim, 1971-
(author)
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Force Budget Analysis of Glacier Flow : Ice Dynamical Studies on Storglaciären, Sweden, and Ice Flow Investigations of Outlet Glaciers in Dronning Maud Land, Antarctica
- 2004
-
Doctoral thesis (other academic/artistic)abstract
- This thesis contributes to the understanding of glacier response to climate change by ice dynamical studies on Storglaciären, Sweden, and Bonnevie-Svendsenbreen, Kibergbreen and Plogbreen in Dronning Maud Land, Antarctica. Ice surface velocities, ice geometry and temperature information is fed through a force budget model to calculate ice mass outflux of these glacial systems via three-dimensional stress distributions for a flux-gate. Field data were collected through repeated DGPS and GPR observations on Storglaciären between July 2000 to September 2001 and on Kibergbreen and Plobreen during the SWEDARP 2002/03 expedition to Antarctica. The work was strongly supported by remotely-sensed information.The results from Storglaciären show a strength in the force budget model to discern both spatial and temporal variability in ice dynamical patterns. It highlights the influence of seasonality and bedrock topography upon glacier flow. A modeling experiment on Bonnevie-Svendsenbreen suggested that ice temperature increases substantially under conditions of high stress (≥0.4 MPa) due to strain-heating. This provides a positive feedback loop, increasing ice deformation, as long as it overcomes the advection of cool ice from the surface. These results explain, to some extent, the mechanism behind fast flowing ice streams. Mass flux caclulations from Bonnevie-Svendsenbreen suggest that the outflux given from force budget calculations can be used as a gauge for influx assuming steady state conditions. Plogbreen receives an influx of 0.48±0.1 km3 a-1 and expedites a discharge volume of 0.55±0.05 km3 a-1. This indicative negative mass balance is explained by a falling trend in upstream accumulation and the recent rise in global sea level, as it is likely to induce glacier acceleration due to a reduction in resistive forces at the site of the gate. This result is comparable with other Antarctic studies reporting negative mass balances, e.g. from WAIS, as caused by changes in the global atmospheric circulation pattern.
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| 13. |
- Hedfors, Jim, et al.
(author)
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Ice flux of Plogbreen, a small ice stream in Dronning Maud Land, Antarctica
- 2004
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In: Annals of Glaciology. - : International Glaciological Society. - 0260-3055 .- 1727-5644. ; 39:1, s. 409-416
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Journal article (peer-reviewed)abstract
- As part of a long-term mass-balance program run by SWEDARP since 1988, a detailed study on Plogbreen, Dronning Maud Land, Antarctica, was undertaken during the austral summer of 2003 to investigate the long-term mass balance. We compare ice outflux, out, through a cross-sectional gate with ice influx, in, from the upstream catchment area. The in is based on calculations of snow accumulation upstream of the gate using data available from published ice-core records. The out is based on Glen's flow law aided by thermodynamic modeling and force-budget calculations. Input data from the field consist of measurements of ice surface velocity and ice geometry. The ice surface velocity was measured using repeated differential global positioning system surveying of 40 stakes over a period of 25 days. The ice geometry was determined by 174 km of ground-penetrating radar profiling using ground-based 8 MHz dipole antennas. This study presents the collected velocity and geometry data as well as the calculated ice flux of Plogbreen. The results show a negatively balanced system within the uncertainty limits; out = 0.55 ± 0.05 km3 a−1 and in = 0.4 ± 0.1 km3 a−1. We speculate that the negative balance can be explained by recent eustatic increase reducing resistive stresses and inducing accelerated flow.
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| 14. |
- Hedfors, Jim, et al.
(author)
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Investigating the ratio of basal drag and driving stress in relation to bedrock topography during a melt season on Storglaciären, Sweden, using force budget analysis
- 2003
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In: Annals of Glaciology. - : International Glaciological Society. - 0260-3055 .- 1727-5644. ; 37:1, s. 263-268
-
Journal article (peer-reviewed)abstract
- We apply the force-budget technique using the isothermal block-flow model, on Storglacia« ren, Sweden, to investigate the ratio between basal drag and driving stress in relation to a bedrock ridge in the bed topography during a peak melt season. The input data consist of glacier surface velocities collected using differential global positioning system surveying of a stake net and geometry fromprevious radar soundings and digitized ice surface maps. The study focuses on the effects of transverse bedrock ridges upon basal stress conditions.The pattern of the calculated ratio of basal drag and driving stress shows a rhythmical position of relatively high and lowbasal drags onthe stoss and lee sides, respectively, of the bedrock thresholds. One of the zones of low basal drag corresponds to the location where the highest basal sliding rate has been measured previously by borehode deformation studies. This zone also aligns with the area where the drainage system is suggested to change from englacial to subglacial.
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| 15. |
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| 16. |
- Hermanson, Mark H., et al.
(author)
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Deposition History of Brominated Flame Retardant Compounds in an Ice Core from Holtedahlfonna, Svalbard, Norway
- 2010
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In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 44:19, s. 7405-7410
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Journal article (peer-reviewed)abstract
- Brominated flame retardants (BFRs) have been found in Arctic wildlife, lake sediment, and air. To identify the atmospheric BFR deposition history on Svalbard, Norway, we analyzed 19 BFRs, including hexabromocyclododecane (HBCD), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), decabromodiphenyl ethane (DBDPE), pentabromoethylbenzene (PBEB), and 15 polybrominated diphenyl ether congeners (PBDE) in the upper 34 m of an ice core (representing 1953-2005) from Holtedahlfonna, the western-most ice sheet on Svalbard. All of the non-PBDE compounds were detected in nearly continuous profiles in the core. Seven PBDEs were not observed above background (28, 47, 66, 100, 99, 154, 153), while 4 were found in 1 or 2 of 6 segments (17, 85, 138, 183). BDEs-49, 71, 190, 209 had nearly continuous profiles but only BDE-209 in large amounts. The greatest inputs were HBCD and BDE-209, 910, and 320 pg cm(-2) yr(-1) from 1995-2005. DBDPE, BTBPE, and PBEB show nearly continuous input growth in recent core segments, but all were <6 pg cm(-2) yr(-1). Long-range atmospheric processes may have moved these particle-bound BFRs to the site, probably during the Arctic haze season. Average air mass trajectories over 10 years show >75% of atmospheric flow to Holtedahlfonna coming from Eurasia during haze periods (March and April).
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| 17. |
- Hooke, Roger LeB., et al.
(author)
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Intra-seasonal changes in deformation profiles revealed by borehole studies, Storglaciären, Sweden.
- 1992
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In: Journal of Glaciology. - 0022-1430 .- 1727-5652. ; 38:130, s. 348-358
-
Journal article (peer-reviewed)abstract
- In 1985, 1987 and 1988, we measured deformation of bore holes in the ablation zone of Storglaciaren. A different hole was used each year. Deformation profiles were determined for four consecutive time periods between mid-July and early September. All three holes were in an area where the glacier lies in an overdeepened part of the bed, up-glacier from a riegel. The first hole was approximately on the glacier center line while the others were midway between the center line and one or the other margin. Despite large standard errors, variations in the deformation profiles during the melt season are broadly consistent with other data. We thus believe that they are real, and that they reflect changes in the stress field resulting from changes in drag at the bed. A decrease in drag early in the melt season, coupled with convergence of the bed contours towards the riegel, is believed to be responsible for a previously documented increase in vertical velocity just upglacier from the riegal at this time of year. Also noteworthy, but perhaps problematical, was an abrupt transverse shear of",! m at a depth of ",25 m near the center of the glacier inJuly 1985. The shear took place in the zone in which cold ice near the surface gives way to temperate ice deeper in the glacier.
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| 18. |
- Ignatiuk, Dariusz, et al.
(author)
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Ground penetrating radar measurement of snow in Svalbard - past, present, future (SnowGPR)
- 2023
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In: SESS report 2022 - The State of Environmental Science in Svalbard - an annual report. - : Svalbard Integrated Arctic Earth Observing System (SIOS).
-
Book chapter (peer-reviewed)abstract
- This is chapter 5 of the State of Environmental Science in Svalbard (SESS) report 2022.Snowpack covers 60-100% of all land in Svalbard, depending on the season, and it is very sensitive to changes in climate. Knowledge about the snowpack is important not just in itself, but also to understand how snow cover affects other components of Svalbard’s natural environment – land, sea, permafrost, glaciers, and the ecosystems that they support. Monitoring the evolution of Svalbard’s snow cover will be crucial as the world’s climate continues to warm.Ground-penetrating radars (GPRs) towed by snowmobile across glaciers and snowfields provide vital information about snowpack thickness and structure. Ideally, such surveys should be repeated annually for continuous monitoring of climate-induced change. Three decades ago, a GPR programme catalogued regional variations in snow accumulation. This should be repeated and expanded to cover all of Svalbard. The GPR method should also be further developed e.g. by mounting GPRs on drones, giving access to parts of glaciers that are too dangerous for researchers to visit. Lastly, women are encouraged to join the field of GPR-based research on snow.Most of the GPR data collected so far are not currently available in any data repository. The comprehensive compilation of available studies presented in this report, and the recommendations for metadata and data quality, are important first steps to making GPR data more accessible.
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| 19. |
- Isaksson, Elisabeth, et al.
(author)
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Climate oscillations as recorded in Svalbard ice core δ 18O records between 1200-1997 AD
- 2005
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In: Geografiska Annaler. Series A, Physical Geography. - : Informa UK Limited. - 0435-3676 .- 1468-0459. ; 87a:1, s. 203-214
-
Journal article (peer-reviewed)abstract
- We apply two different time series analytical tools to omega18O records from two Svalbard ice cores. One ice core is from Lomonosovfonna at 1250 ma.s.l. and the other from Austfonna at 750 m a.s.l. These cores are estimated to cover at least the past 800 years and have been dated using a combination of known reference horizons and glacial modelling. Wavelet analysis reveals low frequency oscillations on the 60-120-year scale on the lower elevation site Austfonna while the higher altitude site on Lomonosovfonna does not reveal such variability throughout the record. The second method, Significant Zero Crossing of Derivates (SiZer) does not resolve the low-frequency periodicity seen in the wavelet analysis. The low-frequency variability resolved by the wavelet analysis is similar to what has been found in various climate records including instrumental temperatures and tree-rings, and has been proposed as the most important oscillation for the observed trends in Arctic air temperatures.
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| 20. |
- Isaksson, Elisabeth, et al.
(author)
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Two ice core δ18O records from Svalbard illustrating climate and sea ice variability over the last 400 years
- 2005
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In: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 15:4, s. 501-509
-
Journal article (peer-reviewed)abstract
- Ice cores from the relatively low-lying ice caps in Svalbard have not been widely exploited in climatic studies owing to uncertainties about the effect of meltwater percolation. However, results from two new Svalbard ice cores, at Lomonosovfonna and Austfonna, have shown that with careful site selection, high-resolution sampling and multiple chemical analyses it is possible to recover ice cores from which part of the annual signals are preserved, despite the considerable meltwater percolation. The new Svalbard ice cores are positioned in different parts of Svalbard and cover the past 800 years. In this paper we focus on the last 400 years. The 6180 signals from the cores are qualitatively similar over most of the twentieth century, suggesting that they record the same atmospheric signal. Prior to AD 1920, the Austfonna ice core exhibits more negative 6180 values than Lomonosovfonna, although there are intermittent decadal-scale periods throughout the record with similar values. We suggest that the differences reflect the effect of the inversion layer during the winter. The pattern in the 6180 records is similar to the Longyearbyen airtemperature record, but on an annual level the correlation is low. The Austfonna record correlates well with the temperature record from the more distant and southwesterly located Jan Mayen. A comparison of the ice-core and sea-ice records from this period suggests that sea-ice extent and Austfonna 6180 are related over the past 400 years. This may reflect the position of the storm tracks and their direct influence on the relatively low-altitude Austfonna. Lomonosovfonna may be less sensitive to such changes and primarily record free atmospheric changes instead of variations in sea-ice extent, the latter is probably a result of its higher elevation.
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| 21. |
- Jawak, Shridhar D., et al.
(author)
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SIOS's Earth Observation (EO), Remote Sensing (RS), and Operational Activities in Response to COVID-19
- 2021
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In: Remote Sensing. - : MDPI. - 2072-4292. ; 13:4
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Journal article (peer-reviewed)abstract
- Svalbard Integrated Arctic Earth Observing System (SIOS) is an international partnership of research institutions studying the environment and climate in and around Svalbard. SIOS is developing an efficient observing system, where researchers share technology, experience, and data, work together to close knowledge gaps, and decrease the environmental footprint of science. SIOS maintains and facilitates various scientific activities such as the State of the Environmental Science in Svalbard (SESS) report, international access to research infrastructure in Svalbard, Earth observation and remote sensing services, training courses for the Arctic science community, and open access to data. This perspective paper highlights the activities of SIOS Knowledge Centre, the central hub of SIOS, and the SIOS Remote Sensing Working Group (RSWG) in response to the unprecedented situation imposed by the global pandemic coronavirus (SARS-CoV-2) disease 2019 (COVID-19). The pandemic has affected Svalbard research in several ways. When Norway declared a nationwide lockdown to decrease the rate of spread of the COVID-19 in the community, even more strict measures were taken to protect the Svalbard community from the potential spread of the disease. Due to the lockdown, travel restrictions, and quarantine regulations declared by many nations, most physical meetings, training courses, conferences, and workshops worldwide were cancelled by the first week of March 2020. The resumption of physical scientific meetings is still uncertain in the foreseeable future. Additionally, field campaigns to polar regions, including Svalbard, were and remain severely affected. In response to this changing situation, SIOS initiated several operational activities suitable to mitigate the new challenges resulting from the pandemic. This article provides an extensive overview of SIOS's Earth observation (EO), remote sensing (RS) and other operational activities strengthened and developed in response to COVID-19 to support the Svalbard scientific community in times of cancelled/postponed field campaigns in Svalbard. These include (1) an initiative to patch up field data (in situ) with RS observations, (2) a logistics sharing notice board for effective coordinating field activities in the pandemic times, (3) a monthly webinar series and panel discussion on EO talks, (4) an online conference on EO and RS, (5) the SIOS's special issue in the Remote Sensing (MDPI) journal, (6) the conversion of a terrestrial remote sensing training course into an online edition, and (7) the announcement of opportunity (AO) in airborne remote sensing for filling the data gaps using aerial imagery and hyperspectral data. As SIOS is a consortium of 24 research institutions from 9 nations, this paper also presents an extensive overview of the activities from a few research institutes in pandemic times and highlights our upcoming activities for the next year 2021. Finally, we provide a critical perspective on our overall response, possible broader impacts, relevance to other observing systems, and future directions. We hope that our practical services, experiences, and activities implemented in these difficult times will motivate other similar monitoring programs and observing systems when responding to future challenging situations. With a broad scientific audience in mind, we present our perspective paper on activities in Svalbard as a case study.
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| 22. |
- Jawak, Shridhar D., et al.
(author)
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Status of Earth Observation and Remote Sensing Applications in Svalbard
- 2023
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In: Remote Sensing. - : MDPI. - 2072-4292. ; 15:2
-
Journal article (other academic/artistic)abstract
- Remarkable developments in the fields of earth observation (EO) satellites and remote sensing (RS) technology over the past four decades have substantially contributed to spatial, spectral, and temporal sampling [...]
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| 23. |
- Johansson, Cecilia, 1974-, et al.
(author)
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Multi-Decadal Changes in Snow Characteristics in Sub-Arctic Sweden
- 2011
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In: Ambio. - : Springer. - 0044-7447 .- 1654-7209. ; 40:6, s. 566-574
-
Journal article (peer-reviewed)abstract
- A unique long term, 49-year record (divided into three time periods 1961–1976, 1977–1992, and 1993–2009) of snow profile stratigraphy from the Swedish sub Arctic, was analyzed with a focus on changes in snow characteristics. The data set contained grain size, snow layer hardness, grain compactness, and snow layer dryness, observed every second week during the winter season. The results showed an increase in very hard snow layers, with harder snow in early winter and more moist snow during spring. There was a striking increase in the number of observations with very hard snow at ground level over time. More than twice as many occasions with hard snow at ground level were observed between 1993 and 2009 compared to previous years, which may have a significant effect on plants and animals. The changes in snow characteristics are most likely a result of the increasing temperatures during the start and the end of the snow season.
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| 24. |
- Jónsdóttir, Kristín, et al.
(author)
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Glacial long period seismic events at Katla volcano, Iceland
- 2009
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In: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 36:11
-
Journal article (peer-reviewed)abstract
- Repeating long-period (lp) earthquakes are commonly observed in volcanic regions worldwide. They are usually explained in terms of a volcanic source effect or anomalous propagation through the volcano. Recently, large lp events have also been associated with the motion of massive ice streams. Our joint analysis of climatic and new seismic data shows that small lp events observed at Katla volcano, Iceland, are in fact related to ice movement in a steep outlet glacier and not, as previously thought, to volcanic intrusive activity. The over 13000 lp events recorded since 2000 are consistent in character and magnitude with seasonal changes of the glacier. As the current global warming trend could cause similar earthquake sequences at other glacier covered volcanoes, identifying them as glacial rather than eruption precursors is vital.
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| 25. |
- Kekonen, Teija, et al.
(author)
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800 year long ion record from the Lomonosovfonna (Svalbard) ice core
- 2005
-
In: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 110:D7
-
Journal article (peer-reviewed)abstract
- We present a high-resolution record of water-soluble ion chemistry from a 121 m ice core spanning about 800 years. The core is well dated to 2/3 depth using cycle counting and reference horizons and a simple but close fitting model for the lower 1/3 of the core. This core suffers from modest seasonal melt, and so we present concentration data in decadal running means to minimize percolation effects. Sea-salt ions (Na+, Cl−, Mg2+, and K+) account for more than 70% of all ions. In general, sea-salt ion concentrations are rather variable and have no clear association with climatic variations. Sulfate, with 74% being from non-sea-salt sources, has higher concentrations than seen on Vestfonna ice cap but lower than in Ny-Ålesund aerosols, suggesting central Spitsbergen receives more marine (westerly) air masses than Ny-Ålesund but more sulfate enriched (easterly) air masses than Nordaustlandet. Clear anthropogenic impacts are found for sulfate, nitrate, and ammonium (and probably excess chloride) after the mid twentieth century, with sulfate showing a significant rise by the end of the nineteenth century. Sulfate and methanesulfonate concentrations correlate well during the twentieth century, and it is clear that most of the preindustrial sulfate is of biogenic origin. Terrestrial component (Ca2+) has the highest concentrations in the coldest part of the Little Ice Age, suggesting more windy conditions, transporting local terrestrial dust to the ice cap. All ion concentrations decrease at the end of the twentieth century, which reflects loss of ions by runoff, with non-sea-salt magnesium being particularly sensitive to melting.
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| 26. |
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| 27. |
- Marchenko, Sergey, et al.
(author)
-
A plot-scale study of firn stratigraphy at Lomonosovfonna, Svalbard, using ice cores, borehole video and GPR surveys in 2012–14
- 2017
-
In: Journal of Glaciology. - : Cambridge University Press (CUP). - 0022-1430 .- 1727-5652. ; 63:237, s. 67-78
-
Journal article (peer-reviewed)abstract
- Spatial heterogeneity of snow and firn properties on glaciers introduces uncertainty in interpretation of point and profile observations and complicates modelling of meltwater percolation and runoff. Here we present a study of the temporal and spatial dynamics of firn density and stratigraphy at the plot-scale (approximate to 10 m x 10 m x 10 m) repeated annually during 2012-14 at the Lomonosovfonna ice-field, Svalbard. Results from cores, video inspections in boreholes and radar grid surveys are compared. Ice layers 0.1-50 cm thick comprised approximate to 8% of the borehole length. Most of them are 1-3 cm thick and could not be traced between boreholes separated by 3 m. Large lateral variability of firn structure affects representativeness of observations in single holes and calls for repeated studies in multiple points to derive a representative stratigraphy signal. Radar reflections are poorly correlated with ice layers in individual boreholes. However, the match between the high amplitude peaks in the grid-averaged radar signal and horizons of preferential ice layer formation revealed by averaging the video surveys over multiple boreholes is higher. These horizons are interpreted as buried firn layers previously exposed to melt-freeze or wind-driven densification and several of them are consistently recovered throughout three field campaigns.
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| 28. |
- Marchenko, Sergey A., et al.
(author)
-
Water content of firn at Lomonosovfonna, Svalbard, derived from subsurface temperature measurements
- 2021
-
In: Journal of Glaciology. - : Cambridge University Press. - 0022-1430 .- 1727-5652. ; 67:265, s. 921-932
-
Journal article (peer-reviewed)abstract
- The potential of capillary forces to retain water in pores is an important property of snow and firn at glaciers. Meltwater suspended in pores does not contribute to runoff and may refreeze during winter, which can affect the climatic mass balance and the subsurface density and temperature. However, measurement of firn water content is challenging and few values have been reported in the literature. Here, we use subsurface temperature and density measured at the accumulation zone of Lomonosovfonna (1200 m a.s.l.), Svalbard, to derive water content of the firn profiles after the 2014 and 2015 melt seasons. We do this by comparing measured and simulated rates of freezing front propagation. The calculated volumetric water content of firn is ~1.0–2.5 vol.% above the depth of 5 m and <0.5 vol.% below. Results derived using different thermistor strings suggest a prominent lateral variability in firn water content. Reported values are considerably lower than those commonly used in snow/firn models. This is interpreted as a result of preferential water flow in firn leaving dry volumes within wetted firn. This suggests that the implementation of irreducible water content values below 0.5 vol.% within snow/firn models should be considered at the initial phase of water infiltration.
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| 29. |
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| 30. |
- Marchenko, Sergey, et al.
(author)
-
Parameterizing deep water percolation improves subsurface temperature simulations by a multilayer firn model
- 2017
-
In: Frontiers in Earth Science. - : Frontiers Media SA. - 2296-6463. ; 5:16
-
Journal article (peer-reviewed)abstract
- Deep preferential percolation of melt water in snow and firn brings water lower along the vertical profile than a laterally homogeneous wetting front. This widely recognized process is an important source of uncertainty in simulations of subsurface temperature, density, and water content in seasonal snow and in firn packs on glaciers and ice sheets. However, observation and quantification of preferential flow is challenging and therefore it is not accounted for by most of the contemporary snow/firn models. Here we use temperature measurements in the accumulation zone of Lomonosovfonna, Svalbard, done in April 2012-2015 using multiple thermistor strings to describe the process of water percolation in snow and firn. Effects of water flow through the snow and firn profile are further explored using a coupled surface energy balance - firn model forced by the output of the regional climate model WRF. In situ air temperature, radiation, and surface height change measurements are used to constrain the surface energy and mass fluxes. To account for the effects of preferential water flow in snow and firn we test a set of depth-dependent functions allocating a certain fraction of the melt water available at the surface to each snow/firn layer. Experiments are performed for a range of characteristic percolation depths and results indicate a reduction in root mean square difference between the modeled and measured temperature by up to a factor of two compared to the results from the default water infiltration scheme. This illustrates the significance of accounting for preferential water percolation to simulate subsurface conditions. The suggested approach to parameterization of the preferential water flow requires low additional computational cost and can be implemented in layered snow/ firn models applied both at local and regional scales, for distributed domains with multiple mesh points.
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| 31. |
- Marchenko, Sergey, 1988-
(author)
-
Subsurface fluxes of mass and energy at the accumulation zone of Lomonosovfonna ice cap, Svalbard
- 2018
-
Doctoral thesis (other academic/artistic)abstract
- Glaciers cover ca 10% of the Earth's land and are found in the high altitudes and latitudes. They are important components of environmental systems due to the multiple feedbacks linking them with the atmosphere, hydrosphere and periglacial landscapes. The cold sloping surfaces of glaciers change the patterns of atmospheric circulation at different scales and at the same time glaciers are largely controlled by climate. They are commonly used as climatic archives for reconstruction of the past environmental changes based on evidences from the areas affected by glaciation at the moment and in the past. Glaciers are the largest fresh-water reservoirs on our planet and runoff thereof significantly affects the global sea level and life in glaciated catchments. However, melt- and rain-induced runoff from glaciers greatly depends on the subsurface conditions which thus need to be taken into account, particularly in a changing climate.This thesis focuses on the processes of subsurface mass and energy exchange in the accumulation zones of glaciers, which are largely driven by the climate at the surface. Results are largely based on empirical data from Lomonosovfonna ice cap, Svalbard, collected during field campaigns in 2012-2017. Observations of subsurface density and stratigraphy using shallow cores, video records from boreholes and radar surveys returned detailed descriptions of the snow and firn layering. The subsurface temperature data collected using multiple thermistor strings provided insights into several subsurface processes. The temperature values measured during three summer seasons were used to constrain the suggested parameterization of deep preferential water flow through snow and firn. The part of data recorded during the cold seasons was employed for an inverse modelling exercise resulting in optimized values of effective thermal conductivity of the subsurface profile. These results are then used to compute the subsurface water content by comparing the simulated and measured rates of freezing front propagation after the melt season in 2014.The field observations and quantitative estimates provide further empirical evidences of preferential water flow in snow/firn packs at glaciers. Results presented in the thesis call for implementation of description of the process in layered models simulating the subsurface fluxes of energy and mass at glaciers. This will result in a better understanding of glacier response to the past and future climatic changes and more accurate estimates of glacier runoff.
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| 32. |
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| 33. |
- Moeller, Marco, et al.
(author)
-
Adjustment of regional climate model output for modeling the climatic mass balance of all glaciers on Svalbard
- 2016
-
In: Journal of Geophysical Research - Atmospheres. - 2169-897X .- 2169-8996. ; 121:10, s. 5411-5429
-
Journal article (peer-reviewed)abstract
- Large-scale modeling of glacier mass balance relies often on the output from regional climate models (RCMs). However, the limited accuracy and spatial resolution of RCM output pose limitations on mass balance simulations at subregional or local scales. Moreover, RCM output is still rarely available over larger regions or for longer time periods. This study evaluates the extent to which it is possible to derive reliable region-wide glacier mass balance estimates, using coarse resolution (10 km) RCM output for model forcing. Our data cover the entire Svalbard archipelago over one decade. To calculate mass balance, we use an index-based model. Model parameters are not calibrated, but the RCM air temperature and precipitation fields are adjusted using in situ mass balance measurements as reference. We compare two different calibration methods: root mean square error minimization and regression optimization. The obtained air temperature shifts (+1.43 degrees C versus +2.22 degrees C) and precipitation scaling factors (1.23 versus 1.86) differ considerably between the two methods, which we attribute to inhomogeneities in the spatiotemporal distribution of the reference data. Our modeling suggests a mean annual climatic mass balance of -0.05 +/- 0.40 mw.e.a(-1) for Svalbard over 2000-2011 and a mean equilibrium line altitude of 452 +/- 200m above sea level. We find that the limited spatial resolution of the RCM forcing with respect to real surface topography and the usage of spatially homogeneous RCM output adjustments and mass balance model parameters are responsible for much of the modeling uncertainty. Sensitivity of the results to model parameter uncertainty is comparably small and of minor importance.
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| 34. |
- Moore, John C., et al.
(author)
-
Statistical extraction of volcanic sulphate from nonpolar ice cores
- 2012
-
In: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 117, s. D03306-
-
Journal article (peer-reviewed)abstract
- Ice cores from outside the Greenland and Antarctic ice sheets are difficult to date because of seasonal melting and multiple sources (terrestrial, marine, biogenic and anthropogenic) of sulfates deposited onto the ice. Here we present a method of volcanic sulfate extraction that relies on fitting sulfate profiles to other ion species measured along the cores in moving windows in log space. We verify the method with a well dated section of the Belukha ice core from central Eurasia. There are excellent matches to volcanoes in the preindustrial, and clear extraction of volcanic peaks in the post-1940 period when a simple method based on calcium as a proxy for terrestrial sulfate fails due to anthropogenic sulfate deposition. We then attempt to use the same statistical scheme to locate volcanic sulfate horizons within three ice cores from Svalbard and a core from Mount Everest. Volcanic sulfate is < 5% of the sulfate budget in every core, and differences in eruption signals extracted reflect the large differences in environment between western, northern and central regions of Svalbard. The Lomonosovfonna and Vestfonna cores span about the last 1000 years, with good extraction of volcanic signals, while Holtedahlfonna which extends to about AD1700 appears to lack a clear record. The Mount Everest core allows clean volcanic signal extraction and the core extends back to about AD700, slightly older than a previous flow model has suggested. The method may thus be used to extract historical volcanic records from a more diverse geographical range than hitherto.
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| 35. |
- Moore, John, et al.
(author)
-
Separation of melting and environmental signals in an ice core with seasonal melt
- 2005
-
In: Geophysical Research Letters. - : AGU. - 0094-8276 .- 1944-8007. ; 32, s. L10501-
-
Journal article (peer-reviewed)abstract
- We examine the impact of melt water percolation on the soluble ion chemical record from the Lomonosovfonna ice core. Principle component analysis shows that melting produces only simple changes between bubbly and clear ice facies, due to elution of ions. The data can be naturally split into four groups: pre-industrial, immediately before, and after the end of the Little Ice Age, and anthropogenic impact eras. The 2nd, 3rd and 4th principle components for these periods all differ significantly, reflecting complex changes in environmental conditions. Thus the core preserves a rich record of environmental history, and simple one of melting. We construct a model of percolation effects to reconstruct “pristine” ice chemical composition, finding that even with melt percentages as high as 80%, there is little disturbance to the chemical stratigraphy. This suggests that ionic records from Arctic ice cap cores are nearly as reliable as those from Greenland or Antarctica.
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| 36. |
- Möller, Marco, et al.
(author)
-
Climatic mass balance of the ice cap Vestfonna, Svalbard : A spatially distributed assessment using ERA-Interim and MODIS data
- 2011
-
In: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 116:F3
-
Journal article (peer-reviewed)abstract
- The ice cap Vestfonna in the northern Svalbard archipelago is one of the largest ice bodies of the European Arctic (similar to 2400 km(2)), but little is known about its mass balance. We model the climatic mass balance of the ice cap for the period September 2000 to August 2009 on a daily basis. Ablation is calculated by a spatially distributed temperature-radiation-index melt model. Air temperature forcing is provided by ERA-Interim data that is downscaled using data from an automatic weather station operated on the ice cap. Spatially distributed net shortwave radiation fluxes are obtained from standard trigonometric techniques combined with Moderate Resolution Imaging Spectroradiometer-based cloud cover and surface albedo information. Accumulation is derived from ERA-Interim precipitation data that are bias corrected and spatially distributed as a function of elevation. Refreezing is incorporated using the P(max) approach. Results indicate that mass balance years are characterized by short ablation seasons (June to August) and correspondingly longer accumulation periods (September to May). The modeled, annual climatic mass balance rate shows an almost balanced mean of -0.02 +/- 0.20 m w.e. yr(-1) (meters water equivalent per year) with an associated equilibrium line altitude of 383 +/- 54 m above sea level (mean +/- one standard deviation). The mean winter balance is +0.32 +/- 0.06 m w.e. yr(-1), and the mean summer balance -0.35 +/- 0.17 m w.e. yr(-1). Roughly one fourth of total surface ablation is retained by refreezing indicating that refreezing is an important component of the mass budget of Vestfonna.
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| 37. |
- Pettersson, Rickard, et al.
(author)
-
Ice thickness and basal conditions of Vestfonna ice cap, eastern Svalbard
- 2011
-
In: Geografiska Annaler. Series A, Physical Geography. - : Informa UK Limited. - 0435-3676 .- 1468-0459. ; 93A:4, s. 311-322
-
Journal article (peer-reviewed)abstract
- We combined ground-based pulsed radar data collected in 20082009 with airborne radio-echo sounding data acquired in 1983 and 1986 over Vestfonna ice cap, Svalbard. The airborne dataset mainly covers the fast-flowing outlet glaciers and the marginal zone, while the ground-based data explicitly cover the interior part of the ice cap. The data presented here are thus the first complete estimate of bed topography and ice thickness. The subglacial landscape undulates with elevations between -160 and +410 m above sea level. The mean ice thickness is 186 m and the total ice area and volume are 2402 km2 and 442 +/- 0.6 km3, respectively. This is a much smaller volume than those derived from empirical volume-area scaling relationships currently used to estimate regional-to-global glacier volumes. This difference may depend on local conditions for Vestfonna and emphasizes the need to include more volume observations in the derivations of volume-area scaling parameters. We also derive basal reflectivity as a proxy for thermal conditions at the bed. Basal reflectivity values suggest that fast-flowing outlet glaciers are underlain by temperate conditions. The geometric boundaries and basal conditions for Vestfonna will be critical additions to the development of numerical models of the ice cap and to the estimation of more accurate area-volume scaling parameters.
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| 38. |
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| 39. |
- Pohjola, Veijo A, 1960-, et al.
(author)
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Investigating the potential to determine the upstream accumulation rate, using mass flux calculations along a cross-section on a small tributary glacier in Heimefrontfjella, Dronning Maud Land, Antarctica
- 2004
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In: Annals of Glaciology. - : International Glaciological Society. - 0260-3055 .- 1727-5644. ; 39:1, s. 175-180
-
Journal article (peer-reviewed)abstract
- How well can we estimate the incoming ice flux by calculating the ice flux through a well-defined cross-section? We test this by comparing calculated ice flux out from the small glacier Bonnevie-Svendsenbreen with the measured accumulation rate integrated over the well-defined catchment area in the Sivorgfjella plateau, Dronning Maud Land, Antarctica (74°45′S, 11°10′W). The ice flux is calculated using ice-dynamical properties from an ice temperature model and the distribution of forces calculated using a force-budget model. The input we use includes velocity data of the glacier surface, combined with ice-thickness measurements. The result is an accumulation rate on the Sivorgfjella plateau of 0.50 ± 0.05 m w.e.a−1. We find that this is similar to the accumulation rate recorded by ground-penetrating radar work in the area. We therefore find the balance-flow method, in combination with the force-budget technique and ice temperature modeling, to be a useful tool for studies of mass fluxes in a catchment area. The most important source of uncertainty in these calculations is the quality and the spatial distribution of the ice surface velocity data. The high accumulation rate shows the effect of orographic enhancement on accumulation in montane areas in Antarctica.
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| 40. |
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| 41. |
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| 42. |
- Pohjola, Veijo A, 1960-, et al.
(author)
-
Spatial distribution and change in the surface ice-velocity field of Vestfonna ice cap, Nordaustlandet, Svalbard, 1995-2010 using geodetic and satellite interferometry data
- 2011
-
In: Geografiska Annaler. Series A, Physical Geography. - : Informa UK Limited. - 0435-3676 .- 1468-0459. ; 93:4, s. 323-335
-
Journal article (peer-reviewed)abstract
- During 2007 we launched a geodetic campaign on the Svalbard ice cap Vestfonna in order to estimate the velocity field of the ice cap. This was done within the frame of the IPY project KINNVIKA. We present here the velocity measurements derived from our campaigns 2007–2010 and compare the geodetic measurements against InSAR velocity fields from satellite platforms from 1995/96 and 2008. We find the spatial distribution of ice speeds from the InSAR is in good agreement within the uncertainty limits with our geodetic measurements. We observe no clear indication of seasonal ice speed differences, but we find a speed-up of the outlet glacier Franklinbreen between the InSAR campaigns, and speculate the outlet is having a surge phase.
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| 43. |
- Pohjola, Veijo, et al.
(author)
-
Controlled experiments on the diffusion rate of stable isotopes of water in artificial firn
- 2007
-
In: Journal of Glaciology. - : International Glaciological Society. - 0022-1430 .- 1727-5652. ; 53:183, s. 537-546
-
Journal article (peer-reviewed)abstract
- We studied the diffusion rate of stable isotopes of water ice in a controlled laboratory experiment, where isotopically different layers of fabricated firn were stacked. This experiment was done in order to study the diffusion rate between the isotopically different layers and to further compare the measured results with forward calculated diffusion rates of the fabricated firn stack, using three different analytical and numerical methods. The layers varied in thickness within the stack and the studied period includes variations in firn temperatures. We sampled the firn-stack on five different dates along the totally 144-d long experiment. We get a quantitatively good match between the calculated and the measured diffusion rates, with a RMS similarity of 67-80 % in the depth averaged diffusion rates. Despite the good average match, we find some qualitative discrepancy between our calculations and our measurements. The calculated diffusion rates predict more than 5 % faster isotopic decay of thinner layers and 13 % slower decay of thicker layers in the experiment than measurements show. This We speculate that grain size and grain fabric may influence the tortuosity the firn pack, and that the current generalization of tortuosity being a function of firn density as the only free parameter is an oversimplification
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| 44. |
- Pohjola, Veijo, et al.
(author)
-
Potential to recover paleoclimatic data in temperate ice cores: an example from the small ice cap Riukojietna, Northern Scandinavia
- 2005
-
In: Geografiska Annaler. Series A, Physical Geography. - : Informa UK Limited. - 0435-3676 .- 1468-0459. ; 87:1, s. 259-270
-
Journal article (peer-reviewed)abstract
- We have studied a 33.7 m deep ice core from a small polythermal Scandinavian ice cap to determine whether it is possible to recover pre-20th century climatic information from the glacier. Ice structural studies show a significant change from clear ice above 11 m depth (superimposed ice indicating refreezing) to bubbly ice below 11 m depth, indicating this is the transition between Little Ice Age (LIA) and 20th century ice. Calculations with a Nye-age model, along with a mass balance reconstruction, show that this structural boundary likely formed in the last part of the LIA, which in this region ended about 1910. The ice below this boundary was sampled and analyzed for stable isotopic composition and ionic content, which both show significant variations with depth. The stable isotope record likely contains cycles of annual duration during the LIA. The chemistry in the ice core indicates that the information is useful, and can be used to interpret climatic and environmental variables during the LIA. A comparison of Riukojietna ion chemistry and oxygen isotope records to similar records from other glaciers in this region reveals a clear continental – maritime gradient. Changes in this gradient with time may be possible to resolve using such ice core records. Results from this study demonstrate that ice cores from glaciers in this climatic environment can be useful in revealing environmental conditions from climatically colder periods and yield pre-industrial benchmark values for chemical loading and oxygen isotopes, but that hiatuses complicate the depth-age relationship.
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| 45. |
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| 46. |
- Riseth, Jan Åge, et al.
(author)
-
Sámi traditional ecological knowledge as a guide to science : snow, ice and reindeer pasture facing climate change
- 2011
-
In: Polar Record. - : Cambridge University Press. - 0032-2474 .- 1475-3057. ; 47:3, s. 202-217
-
Journal article (peer-reviewed)abstract
- Scientific studies of challenges of climate change could be improved by including other sources of knowledge, such as traditional ecological knowledge (TEK), in this case relating to the Sámi. This study focuses on local variations in snow and ice conditions, effects of the first durable snow, and long term changes in snow and ice conditions as pre-requisites for understanding potential future changes. Firstly, we characterised snow types and profiles based on Sámi categories and measured their density and hardness. Regression analysis showed that density can explain much of the variation in hardness, while snow depth was not significantly correlated with hardness. Secondly, we found that whether it is dry/cold or warm/wet around the fall of the first durable snow is, according to Sámi reindeer herders, crucial information for forecasting winter grazing conditions, but this has had limited focus within science. Thirdly, elderly herders’ observations of changes in snow and ice conditions by ‘reading nature’ can aid reinterpretation of meteorological data by introducing researchers to alternative perspectives. In conclusion we found remarkable agreement between scientific measurements and Sámi terminology.We also learnt that TEK/science cooperation has much potential for climate change studies, though time and resources are needed to bridge the gap between knowledge systems. In particular, TEK attention to shifts in nature can be a useful guide for science.
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| 47. |
- Ruggirello, Rachel M., et al.
(author)
-
Current use and legacy pesticide deposition to ice caps on Svalbard, Norway
- 2010
-
In: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 115, s. D18308-
-
Journal article (peer-reviewed)abstract
- Transport and deposition of current use (CUP) and legacy pesticides (LP) and residual products to the Arctic have been documented in abiotic matrices. These observations show that some "low-persistence" pesticides with high OH center dot reaction rates are stable enough to accumulate in a polar environment. In 2005, we drilled an ice core on Holtedahlfonna, one of the major ice fields on Svalbard, Norway to measure the input of 47 CUPs and 17 LPs to a high-elevation abiotic environment with no local pesticide sources. Of these, 9 CUPs and 12 LPs were observed in at least one of 6 core segments dating to 1953: 15 of these were found in enough core segments to reveal time-related trends. CUPs often observed included chlorpyrifos, dacthal, alpha- and beta- endosulfan, endosulfan sulfate, trifluralin, and gamma-HCH. LPs most often observed included methoxychlor, alpha- and gamma-chlordane, cis- and trans- nonachlor, endrin, dieldrin, and p, p'-DDE. In our comparison of core burdens at Holtedahlfonna and Austfonna (220 km ENE from Holtedahlfonna), we found twice as many CUPs at Austfonna along with greater amounts of dieldrin, methoxychlor, alpha-endosulfan and chlorpyrifos suggesting different accumulation processes or sources. Air mass back trajectories over a 10-year period of comparison between sites (1986-1995) show air mass flow from Eurasia 74% of the time to Austfonna and 45% to Holtedahfonna which may account for some of the differences.
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| 48. |
- Samyn, D., et al.
(author)
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Nitrate and Sulfate Anthropogenic Trends in the 20th Century from Five Svalbard Ice Cores
- 2012
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In: Arctic, Antarctic and Alpine research. - : Informa UK Limited. - 1523-0430 .- 1938-4246. ; 44:4, s. 490-499
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Journal article (peer-reviewed)abstract
- Sulfate and nitrate records from 5 ice cores spread across Svalbard were compared and revealed strong temporal similarities with previously published global estimates of SO2 and NOx anthropogenic emissions during the 20th century. A significant departure from the early century sulfate and nitrate levels was evident at all drilling sites starting from the mid-1940s. A steady increase was observed in both sulfate and nitrate profiles at most sites until the late 1960s, when the annual concentrations started to increase at a higher rate. This peak activity lasted for about a decade, and was observed to decrease steadily from the early 1980s on, when sulfate levels declined significantly and when nitrate levels finally reached sulfate levels for the first time in 20th century. The timing of these trends in Svalbard with global SO2 and NOx concentration profiles was best appraised when considering composite concentration profiles of all Svalbard ice cores for sulfate and nitrate, respectively. Composite profiles were also found to provide a convenient mean for distinguishing between the most important world source regions. Based on correlation analysis, the major pollutant sources appeared to be Western Europe and North America for both sulfate and nitrate, followed by Central Europe and former U.S.S.R. in generally similar proportions.
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| 49. |
- Schafer, M., et al.
(author)
-
Assessment of heat sources on the control of fast flow of Vestfonna ice cap, Svalbard
- 2014
-
In: The Cryosphere. - : Copernicus GmbH. - 1994-0416 .- 1994-0424. ; 8:5, s. 1951-1973
-
Journal article (peer-reviewed)abstract
- Understanding the response of fast flowing ice streams or outlet glaciers to changing climate is crucial in order to make reliable projections of sea level change over the coming decades. Motion of fast outlet glaciers occurs largely through basal motion governed by physical processes at the glacier bed, which are not yet fully understood. Various subglacial mechanisms have been suggested for fast flow but common to most of the suggested processes is the requirement of presence of liquid water, and thus temperate conditions. We use a combination of modelling, field, and remote observations in order to study links between different heat sources, the thermal regime and basal sliding in fast flowing areas on Vestfonna ice cap. A special emphasis lies on Franklinbreen, a fast flowing outlet glacier which has been observed to accelerate recently. We use the ice flow model Elmer/Ice including a Weertman type sliding law and a Robin inverse method to infer basal friction parameters from observed surface velocities. Firn heating, i.e. latent heat release through percolation of melt water, is included in our model; its parameterisation is calibrated with the temperature record of a deep borehole. We found that strain heating is negligible, whereas friction heating is identified as one possible trigger for the onset of fast flow. Firn heating is a significant heat source in the central thick and slow flowing area of the ice cap and the essential driver behind the ongoing fast flow in all outlets. Our findings suggest a possible scenario of the onset and maintenance of fast flow on the Vestfonna ice cap based on thermal processes and emphasise the role of latent heat released through refreezing of percolating melt water for fast flow. However, these processes cannot yet be captured in a temporally evolving sliding law. In order to simulate correctly fast flowing outlet glaciers, ice flow models not only need to account fully for all heat sources, but also need to incorporate a sliding law that is not solely based on the basal temperature, but also on hydrology and/or sediment physics.
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| 50. |
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