| 1. |
- Zdanowicz, Christian, 1966-, et al.
(författare)
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Elemental and water-insoluble organic carbon in Svalbard snow: a synthesis of observations during 2007-2018
- 2021
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 21:4, s. 3035-3057
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Tidskriftsartikel (refereegranskat)abstract
- Light-absorbing carbonaceous aerosols emitted by biomass or fossil fuel combustion can contribute to amplifying Arctic climate warming by lowering the albedo of snow. The Svalbard archipelago, being near to Europe and Russia, is particularly affected by these pollutants, and improved knowledge of their distribution in snow is needed to assess their impact. Here we present and synthesize new data obtained on Svalbard between 2007 and 2018, comprising measurements of elemental (EC) and water-insoluble organic carbon (WIOC) in snow from 37 separate sites. We used these data, combined with meteorological data and snowpack modeling, to investigate the variability of EC and WIOC deposition in Svalbard snow across latitude, longitude, elevation and time. Overall, EC concentrations (C-snow(EC)) ranged from < 1.0 to 266.6 ng g(-1), while WIOC concentrations (C-snow(WIOC)) ranged from < 1 to 9426 ng g(-1), with the highest values observed near Ny-Alesund. Calculated snowpack loadings (L-snow(EC), L-snow(WIOC)) on glaciers surveyed in spring 2016 were 0.1 to 2.6 mg m(-2) and 2 to 173 mg m(-2), respectively. The median C-snow(EC) and the L-snow(EC) on those glaciers were close to or lower than those found in earlier (2007- 2009), comparable surveys. Both L-snow(EC) and L(snow)(WIOC )increased with elevation and snow accumulation, with dry deposition likely playing a minor role. Estimated area-averaged snowpack loads across Svalbard were 1.1 mg EC m(-2) and 38.3 mg WIOC m(-2) for the 2015-2016 winter. An similar to 11-year long dataset of spring surface snow measurements from the central BrOgger Peninsula was used to quantify the interannual variability of EC and WIOC deposition in snow. In most years, C-snow(EC) and C-snow(WIOC) at Ny-Alesund (50 m a.s.l.) were 2-5 times higher than on the nearby Austre Brogger-breen glacier (456 m a.s.l.), and the median EC/WIOC in Ny-Alesund was 6 times higher, suggesting a possible influence of local EC emission from Ny-Alesund. While no long-term trends between 2011 and 2018 were found, C-snow(EC) and C-snow(WIOC) showed synchronous variations at Ny-Alesund and Austre Broggerbreen. When compared with data from other circum-Arctic sites obtained by comparable methods, the median C(snow)(EC)on Svalbard falls between that found in central Greenland (lowest) and those in continental sectors of European Arctic (northern Scandinavia, Russia and Siberia; highest), which is consistent with large-scale patterns of BC in snow reported by surveys based on other methods.
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| 2. |
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| 3. |
- Marchenko, Sergey, et al.
(författare)
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A plot-scale study of firn stratigraphy at Lomonosovfonna, Svalbard, using ice cores, borehole video and GPR surveys in 2012–14
- 2017
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Ingår i: Journal of Glaciology. - : Cambridge University Press (CUP). - 0022-1430 .- 1727-5652. ; 63:237, s. 67-78
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Oerlemans, Johannes, et al.
(författare)
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A model study of Abrahamsenbreen, a surging glacier in northern Spitsbergen
- 2015
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Ingår i: The Cryosphere. - : Copernicus GmbH. - 1994-0416 .- 1994-0424. ; 9:2, s. 767-779
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Tidskriftsartikel (refereegranskat)abstract
- The climate sensitivity of Abrahamsenbreen, a 20 km long surge-type glacier in northern Spitsbergen, is studied with a simple glacier model. A scheme to describe the surges is included, which makes it possible to account for the effect of surges on the total mass budget of the glacier. A climate reconstruction back to AD 1300, based on ice-core data from Lomonosovfonna and climate records from Longyearbyen, is used to drive the model. The model is calibrated by requesting that it produce the correct Little Ice Age maximum glacier length and simulate the observed magnitude of the 1978 surge. Abrahamsenbreen is strongly out of balance with the current climate. If climatic conditions remain as they were for the period 1989–2010, the glacier will ultimately shrink to a length of about 4 km (but this will take hundreds of years). For a climate change scenario involving a 2 m year−1 rise of the equilibrium line from now onwards, we predict that in the year 2100 Abrahamsenbreen will be about 12 km long. The main effect of a surge is to lower the mean surface elevation and thereby to increase the ablation area, causing a negative perturbation of the mass budget. We found that the occurrence of surges leads to a faster retreat of the glacier in a warming climate. Because of the very small bed slope, Abrahamsenbreen is sensitive to small perturbations in the equilibrium-line altitude. If the equilibrium line were lowered by only 160 m, the glacier would steadily grow into Woodfjorddalen until, after 2000 years, it would reach Woodfjord and calving would slow down the advance. The bed topography of Abrahamsenbreen is not known and was therefore inferred from the slope and length of the glacier. The value of the plasticity parameter needed to do this was varied by +20 and −20%. After recalibration the same climate change experiments were performed, showing that a thinner glacier (higher bedrock in this case) in a warming climate retreats somewhat faster.
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| 5. |
- van Pelt, Ward, et al.
(författare)
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Inverse estimation of snow accumulation along a radar transect on Nordenskioldbreen, Svalbard
- 2014
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Ingår i: Journal of Geophysical Research - Earth Surface. - 2169-9003 .- 2169-9011. ; 119:4, s. 816-835
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Tidskriftsartikel (refereegranskat)abstract
- We present an inverse modeling approach to reconstruct annual accumulation patterns from ground-penetrating radar (GPR) data. A coupled surface energy balance-snow model simulates surface melt and the evolution of subsurface density, temperature, and water content. The inverse problem consists of iteratively calibrating accumulation, serving as input for the model, by finding a match between modeled and observed radar travel times. The inverse method is applied to a 16km GPR transect on Nordenskioldbreen, Svalbard, yielding annual accumulation patterns for 2007-2012. Accumulation patterns with a mean of 0.75meter water equivalent (mwe)a(-1)contain substantial spatial variability, with a mean annual standard deviation of 0.17mwea(-1), and show only partial consistency from year to year. In contrast to traditional methods, accounting for melt water percolation, refreezing, and runoff facilitates accurate accumulation reconstruction in areas with substantial melt. Additionally, accounting for horizontal density variability along the transect is shown to reduce spatial variability in reconstructed accumulation, whereas incorporating irreducible water storage lowers accumulation estimates. Correlating accumulation to terrain characteristics in the dominant wind direction indicates a strong preference of snow deposition on leeward slopes, whereas weaker correlations are found with terrain curvature. Sensitivity experiments reveal a nonlinear response of the mass balance to accumulation changes. The related negative impact of small-scale accumulation variability on the mean net mass balance is quantified, yielding a negligible impact in the accumulation zone and a negative impact of -0.09mwea(-1)in the ablation area.
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| 6. |
- van Pelt, Ward J. J., et al.
(författare)
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Multi-decadal climate and seasonal snow conditions in Svalbard
- 2016
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Ingår i: Journal of Geophysical Research - Earth Surface. - 2169-9003 .- 2169-9011. ; 121:11, s. 2100-2117
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Tidskriftsartikel (refereegranskat)abstract
- Svalbard climate is undergoing amplified change with respect to the global mean. Changing climate conditions directly affect the evolution of the seasonal snowpack, through its impact on accumulation, melt, and moisture exchange. We analyze long-term trends and spatial patterns of seasonal snow conditions in Svalbard between 1961 and 2012. Downscaled regional climate model output is used to drive a snow modeling system (SnowModel), with coupled modules simulating the surface energy balance and snowpack evolution. The precipitation forcing is calibrated and validated against snow depth data on a set of glaciers around Svalbard. Climate trends reveal seasonally inhomogeneous warming and a weakly positive precipitation trend, with strongest changes in the north. In response to autumn warming the date of snow onset increased (2days decade(-1)), whereas in spring/summer opposing effects cause a nonsignificant trend in the snow disappearance date. Maximum snow water equivalent (SWE) in winter/spring shows a modest increase (+0.01 meters water equivalent (mwe)decade(-1)), while the end-of-summer minimum snow area fraction declined strongly (from 48% to 36%). The equilibrium line altitude is highest in relatively dry inland regions, and time series show a clear positive trend (25mdecade(-1)) as a result of summer warming. Finally, rain-on-snow in the core winter season, affecting ground ice formation and limiting access of grazing animals to food supplies, peaks during specific years (1994, 1996, 2000, and 2012) and is found to be concentrated in the lower lying coastal regions in southwestern Svalbard.
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| 7. |
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| 8. |
- van Pelt, Ward, et al.
(författare)
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Modelling the long-term mass balance and firn evolution of glaciers around Kongsfjorden, Svalbard
- 2015
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Ingår i: Journal of Glaciology. - 0022-1430 .- 1727-5652. ; 61:228, s. 731-744
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Tidskriftsartikel (refereegranskat)abstract
- We analyse the long-term (1961-2012) distributed surface mass balance and firn evolution of the Kongsvegen and Holtedahlfonna glacier systems in northwestern Svalbard. We couple a surface energy-balance model to a firn model, with forcing provided from regional climate model output. In situ observational data are used to calibrate model parameters and validate the output. The simulated area-averaged surface mass balance for 1961-2012 is slightly positive (0.08 m w.e. a(-1)), which only fractionally compensates for mass loss by calving. Refreezing of percolating water in spring/summer (0.13 m w.e. a(-1)) and stored water in fall/winter (0.18 m w.e. a(-1)) provides a buffer for runoff. Internal accumulation, i.e. refreezing below the previous year's summer surface in the accumulation zone, peaks up to 0.22 m w.e. a(-1), and is unaccounted for by stake observations. Superimposed ice formation in the lower accumulation zone ranges as high as 0.25 m w.e. a(-1). A comparison of the periods 1961-99 and 2000-12 reveals 21% higher annual melt rates since 2000 and a 31% increase in runoff, which can only in part be ascribed to recent warmer and drier conditions. In response to firn line retreat, both albedo lowering (snow/ice-albedo feedback) and lower refreezing rates (refreezing feedback) further amplified runoff.
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| 9. |
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| 10. |
- van Pelt, Ward, et al.
(författare)
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Simulating melt, runoff and refreezing on Nordenskiöldbreen, Svalbard, using a coupled snow and energy balance model
- 2012
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Ingår i: The Cryosphere. - : Copernicus GmbH. - 1994-0416 .- 1994-0424. ; 6:3, s. 641-659
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Tidskriftsartikel (refereegranskat)abstract
- A distributed energy balance model is coupled to a multi-layer snow model in order to study the mass balance evolution and the impact of refreezing on the mass budget of Nordenskioldbreen, Svalbard. The model is forced with output from the regional climate model RACMO and meteorological data from Svalbard Airport. Extensive calibration and initialisation are performed to increase the model accuracy. For the period 1989-2010, we find a mean net mass balance of -0.39 m w.e. a(-1). Refreezing contributes on average 0.27 m w.e. a(-1) to the mass budget and is most pronounced in the accumulation zone. The simulated mass balance, radiative fluxes and subsurface profiles are validated against observations and are generally in good agreement. Climate sensitivity experiments reveal a non-linear, seasonally dependent response of the mass balance, refreezing and runoff to changes in temperature and precipitation. It is shown that including seasonality in climate change, with less pronounced summer warming, reduces the sensitivity of the mass balance and equilibrium line altitude (ELA) estimates in a future climate. The amount of refreezing is shown to be rather insensitive to changes in climate.
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