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Applying a Mesoscale Atmospheric Model to Svalbard Glaciers  [PDF]
Bj?rn Claremar,Friedrich Obleitner,Carleen Reijmer,Veijo Pohjola,Anna Waxeg?rd,Florian Karner,Anna Rutgersson
Advances in Meteorology , 2012, DOI: 10.1155/2012/321649
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. 1. Introduction The Svalbard archipelago experienced a significant thinning of its glacial mass over the last century, which contributed about 0.026?mm?yr?1 sea-level rise over the last 50 years [1–4]. In consequence, the stratification and circulation of fjord systems respond to enhanced fresh water supply by melt water and icebergs from calving glaciers [5]. Significant changes are also observed regarding Svalbard sea ice, permafrost, or land and marine ecosystems [6–10]. The thinning and retreat of glaciers on Svalbard is probably both an effect of the warming that set off after the little ice age and the warming of the Arctic over the last decade that likely is an effect of anthropogenic greenhouse gas forcing [11]. The Svalbard archipelago has also experienced a significantly increased precipitation since the 1960s [12]. Several projects have recently been initiated to better understand these detected environmental changes and the response of the Arctic cryosphere (e.g., SVALI; http://www.ncoe-svali.org or SvalGlac; http://svalglac.eu). SVALI (Stability and Variations of Arctic Land Ice) is a Nordic centre of excellence, initiated by the Nordic council of ministers, with the focus to study the interaction between climate change and the cryosphere, with focus on glaciers in the Arctic/North Atlantic
Observations of enhanced thinning in the upper reaches of Svalbard glaciers  [PDF]
T. D. James,T. Murray,N. E. Barrand,H. J. Sykes
The Cryosphere , 2012, DOI: 10.5194/tc-6-1369-2012
Abstract: Changes in the volume and extent of land ice of the Svalbard archipelago have been the subject of considerable research since their sensitivity to changes in climate was first noted. However, the measurement of these changes is often necessarily based on point or profile measurements which may not be representative if extrapolated to a whole catchment or region. Combining high-resolution elevation data from contemporary laser-altimetry surveys and archived aerial photography makes it possible to measure historical changes across a glacier's surface without the need for extrapolation. Here we present a high spatial resolution time-series for six Arctic glaciers in the Svalbard archipelago spanning 1961 to 2005. We find high variability in thinning rates between sites with prevalent elevation changes at all sites averaging 0.59 ± 0.04 m a 1 between 1961–2005. Prior to 1990, ice surface elevation was changing at an average rate of 0.52 ± 0.09 m a 1 which decreased to 0.76 ± 0.10 m a 1 after 1990. Setting the elevation changes against the glaciers' altitude distribution reveals that significant increases in thinning rates are occurring most notably in the glaciers' upper reaches. We find that these changes are coincident with a decrease in winter precipitation at the Longyearbyen meteorological station and could reflect a decrease in albedo or dynamic response to lower accumulation. Further work is required to understand fully the causes of this increase in thinning rates in the glaciers' upper reaches. If on-going and occurring elsewhere in the archipelago, these changes will have a significant effect on the region's future mass balance. Our results highlight the importance of understanding the climatological context of geodetic mass balance measurements and demonstrate the difficulty of using index glaciers to represent regional changes in areas of strong climatological gradients.
Applying a Mesoscale Atmospheric Model to Svalbard Glaciers  [PDF]
Bj rn Claremar,Friedrich Obleitner,Carleen Reijmer,Veijo Pohjola,Anna Waxeg rd,Florian Karner,Anna Rutgersson
Advances in Meteorology , 2012, DOI: 10.1155/2012/321649
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.
Observations of widespread accelerated thinning in the upper reaches of Svalbard glaciers  [PDF]
T. D. James,T. Murray,N. E. Barrand,H. J. Sykes
The Cryosphere Discussions , 2012, DOI: 10.5194/tcd-6-1085-2012
Abstract: The measured rise in eustatic sea level over the 20th century was dominated by mass loss from the world's mountain glaciers and ice caps, and predictions suggest that these fresh water reservoirs will remain significant into the 21st century. However, estimates of this mass transfer to the ocean are based on a limited number of observations extrapolated to represent not only regional changes but often changes across individual glaciers. Combining high resolution elevation data from contemporary laser-altimetry surveys and archived aerial photography makes it possible to measure historical changes across a glacier's entire surface. Here we present a high spatial resolution time-series for six Arctic glaciers in the Svalbard Archipelago spanning 1961 to 2005. We find increasing thinning rates before and after 1990 with elevation losses occurring most notably in the glaciers' upper reaches. In the absence of a clear meteorological driver, we recommend further investigation into a possible albedo amplification of prevailing meteorological trends to explain these higher elevation changes, which could have important consequences on the region's mass balance due to the sensitivity of its hypsometric distribution. However, the strong influence of decadal-scale variability, while explaining lower rates of mass loss reported in earlier studies, highlights that caution must be exercised when interpreting thinning rates when averaged over long periods.
Seasonal speed-up of two outlet glaciers of Austfonna, Svalbard, inferred from continuous GPS measurements  [PDF]
T. Dunse,T. V. Schuler,J. O. Hagen,C. H. Reijmer
The Cryosphere , 2012, DOI: 10.5194/tc-6-453-2012
Abstract: A large part of the ice discharge from ice caps and ice sheets occurs through spatially limited flow units that may operate in a mode of steady flow or cyclic surge behaviour. Changes in the dynamics of distinct flow units play a key role in the mass balance of Austfonna, the largest ice cap on Svalbard. The recent net mass loss of Austfonna was dominated by calving from marine terminating outlet glaciers. Previous ice-surface velocity maps of the ice cap were derived by satellite radar interferometry (InSAR) and rely on data acquired in the mid-1990s with limited information concerning the temporal variability. Here, we present continuous Global Positioning System (GPS) observations along the central flowlines of two fast flowing outlet glaciers over 2008–2010. The data show prominent summer speed-ups with ice-surface velocities as high as 240% of the pre-summer mean. Acceleration follows the onset of the summer melt period, indicating enhanced basal motion due to input of surface meltwater into the subglacial drainage system. In 2008, multiple velocity peaks coincide with successive melt periods. In 2009, the major melt was of higher amplitude than in 2008. Flow velocities appear unaffected by subsequent melt periods, suggesting a transition towards a hydraulically more efficient drainage system. The observed annual mean velocities of Duvebreen and Basin-3 exceed those from the mid-1990s by factors two and four, respectively, implying increased ice discharge at the calving front. Measured summer velocities up to 2 m d 1 for Basin-3 are close to those of Kronebreen, often referred to as the fastest glacier on Svalbard.
Seasonal speed-up of two outlet glaciers of Austfonna, Svalbard, inferred from continuous GPS measurements  [PDF]
T. Dunse,T. V. Schuler,J. O. Hagen,C. H. Reijmer
The Cryosphere Discussions , 2011, DOI: 10.5194/tcd-5-3423-2011
Abstract: A large part of the ice discharge from ice caps and ice sheets occurs through spatially limited flow units that may operate in a mode of steady flow or cyclic surge behaviour. Changes in the dynamics of distinct flow units play a key role in the mass balance of Austfonna, the largest ice cap on Svalbard. The recent net mass loss of Austfonna was dominated by calving from marine terminating outlet glaciers. Previous ice-surface velocity maps of the ice cap were derived by satellite radar interferometry (InSAR) and rely on data acquired in the mid-1990s with limited information concerning the temporal variability. Here, we present continuous Global Positioning System (GPS) observations along the central flowlines of two fast flowing outlet glaciers over 2008 2010. The data show prominent summer speed-ups with ice-surface velocities as high as 240 % of the pre-summer mean. Acceleration follows the onset of the summer melt period, indicating enhanced basal motion due to input of surface meltwater into the subglacial drainage system. In 2008, multiple velocity peaks coincide with successive melt periods. In 2009, the principle melt was of higher amplitude than in 2008. Flow velocities appear unaffected by subsequent melt periods, suggesting a transition towards a hydraulically more efficient drainage system. The observed annual mean velocities of Duvebreen and Basin-3 exceed those from the mid-1990s by factors two and four, respectively, implying increased ice discharge at the calving front. Measured summer velocities up to 2 m d 1 for Basin-3 are close to that of Kronebreen, often referred to as the fastest glacier on Svalbard.
A surge of the glaciers Skobreen–Paulabreen, Svalbard, observed by time-lapse photographs and remote sensing data
Lene Kristensen,Douglas I. Benn
Polar Research , 2012, DOI: 10.3402/polar.v31i0.11106
Abstract: We present observations of a surge of the glaciers Skobreen–Paulabreen, Svalbard, during 2003–05, including a time-lapse movie of the frontal advance during 2005, Advanced Spaceborne Thermal Emission (ASTER) imagery and oblique aerial photographs. The surge initiated in Skobreen, and then propagated downglacier into the lower parts of Paulabreen. ASTER satellite images from different stages of the surge are used to evaluate the surge progression. Features on the glacier surface advanced 2800 m over 2.4 yr, averaging 3.2 m/day, while the front advanced less (ca. 1300 m) due to contemporaneous calving. The surge resulted in a lateral displacement of the medial moraines of Paulabreen of ca. 600 m at the glacier front. The time-lapse movie captured the advance of the frontal part of the glacier, and dramatically illustrates glacier dynamic processes in an accessible way. The movie documents a range of processes such as a plug-like flow of the glacier, proglacial thrusting, incorporation of old, dead ice at the margin, and calving into the fjord. The movie provides a useful resource for researchers, educators seeking to teach and inspire students, and those wishing to communicate the fascination of glacier science to a wider public.
Supraglacial dust and debris: geochemical compositions from glaciers in Svalbard, southern Norway, Nepal and New Zealand
K. A. Casey
Earth System Science Data Discussions , 2012, DOI: 10.5194/essdd-5-107-2012
Abstract: Alpine glacier samples were collected in four contrasting regions to measure supraglacial dust and debris geochemical composition and quantify regional variability. A total of 70 surface glacier ice, snow and debris samples were collected in Svalbard, southern Norway, Nepal and New Zealand. Trace elemental abundances in snow and ice samples were measured via inductively coupled plasma mass spectrometry (ICP-MS). Supraglacial debris mineral, bulk oxide and trace element composition were determined via X-ray diffraction (XRD) and X-ray fluorescence spectroscopy (XRF). A total of 45 major, trace and rare earth elements and 10 oxide compound abundances are reported. Elemental abundances revealed sea salt aerosol and metal enrichment in Svalbard, low levels of crustal dust and marine influences to southern Norway, high crustal dust and anthropogenic enrichment in the Khumbu Himalayas, and sulfur and metals attributed to quiescent degassing and volcanic activity in northern New Zealand. Rare earth element and Al/Ti elemental ratios demonstrated distinct provenance of particulates in each study region. Ca/S elemental ratio data showed seasonal denudation in Svalbard and southern Norway. Ablation season atmospheric particulate transport trajectories were mapped in each of the study regions and suggest provenance pathways. The in situ data presented provides first-order glacier surface geochemical variability as measured in the four diverse alpine glacier regions. The surface glacier geochemical data set is available from the PANGAEA database at doi:10.1594/PANGAEA.773951. This geochemical surface glacier data is relevant to glaciologic ablation rate understanding as well as satellite atmospheric and land-surface mapping techniques currently in development.
Cellulolysis in the fermentation chambers in Svalbard reindeer
W. S?rmo,?. E. Haga,S. D. Mathiesen
Rangifer , 1998,
Abstract: Cellulolysis in the fermentation chambers in Svalbard reindeer
Microbiology of digestion in the Svalbard reindeer (Rangifer tarandus platyrhynchus)
Colin G. Orpin,Svein Disch Mathiesen
Rangifer , 1990,
Abstract: Microbiology of digestion in the Svalbard reindeer
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