scholarly journals Climate sensitivity of glaciers in southern Norway: application of an energy-balance model to Nigardsbreen, Hellstugubreen and Alfotbreen

1992 ◽  
Vol 38 (129) ◽  
pp. 223-232 ◽  
Author(s):  
J. Oerlemans
Keyword(s):  
Energy Balance ◽  
Mass Balance ◽  
Climate Sensitivity ◽  
Flow Model ◽  
Energy Balance Model ◽  
Balance Model ◽  
Equilibrium Line Altitude ◽  
Ice Flow ◽  
Calculated Mass ◽  
Southern Norway

AbstractThree glaciers in southern Norway, with very different mass-balance characteristics, are studied with an energy-balance model of the ice/snow surface. The model simulates the observed mass-balance profiles in a satisfactory way, and can thus be used with some confidence in a study of climate sensitivity. Calculated changes in equilibrium-line altitude for a 1 K temperature increase are 110, 108 and 135 m for Nigardsbreen, Hellstugubreen and Alfotbreen, respectively. The corresponding changes in mass balance, averaged over the entire glacier area, are −0.88, −0.715 and −1.11 m year−1 (water equivalent).Runs with an ice-flow model for Nigardsbreen, to which calculated mass-balance profiles arc imposed, predict that the front will advance by 3 km for a 1 K cooling, and will retreat by as much as 6.5 km for a 1 K warming. The response to a 10% increase in precipitation would be a 2 km advance of the snout, whereas a 4 km retreat is predicted for a 10% decrease. This large sensitivity (as compared to many other glaciers) is to a large extent due to the geometry of Nigardsbreen.

Climate sensitivity of glaciers in southern Norway: application of an energy-balance model to Nigardsbreen, Hellstugubreen and Alfotbreen

1992 ◽  
Vol 38 (129) ◽  
pp. 223-232 ◽  
Author(s):  
J. Oerlemans
Keyword(s):  
Energy Balance ◽  
Mass Balance ◽  
Climate Sensitivity ◽  
Flow Model ◽  
Energy Balance Model ◽  
Balance Model ◽  
Equilibrium Line Altitude ◽  
Ice Flow ◽  
Calculated Mass ◽  
Southern Norway

AbstractThree glaciers in southern Norway, with very different mass-balance characteristics, are studied with an energy-balance model of the ice/snow surface. The model simulates the observed mass-balance profiles in a satisfactory way, and can thus be used with some confidence in a study of climate sensitivity. Calculated changes in equilibrium-line altitude for a 1 K temperature increase are 110, 108 and 135 m for Nigardsbreen, Hellstugubreen and Alfotbreen, respectively. The corresponding changes in mass balance, averaged over the entire glacier area, are −0.88, −0.715 and −1.11 m year−1(water equivalent).Runs with an ice-flow model for Nigardsbreen, to which calculated mass-balance profiles arc imposed, predict that the front will advance by 3 km for a 1 K cooling, and will retreat by as much as 6.5 km for a 1 K warming. The response to a 10% increase in precipitation would be a 2 km advance of the snout, whereas a 4 km retreat is predicted for a 10% decrease. This large sensitivity (as compared to many other glaciers) is to a large extent due to the geometry of Nigardsbreen.

scholarly journals Simulating melt, runoff and refreezing on Nordenskiöldbreen, Svalbard, using a coupled snow and energy balance model

2012 ◽  
Vol 6 (3) ◽  
pp. 641-659 ◽  
Author(s):  
W. J. J. van Pelt ◽  
J. Oerlemans ◽  
C. H. Reijmer ◽  
V. A. Pohjola ◽  
R. Pettersson ◽  
...  
Keyword(s):  
Energy Balance ◽  
Mass Balance ◽  
Climate Model ◽  
Meteorological Data ◽  
Regional Climate ◽  
Energy Balance Model ◽  
Balance Model ◽  
Equilibrium Line Altitude ◽  
Mass Budget ◽  
The Impact

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 Nordenskiöldbreen, 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.

scholarly journals Simulating melt, runoff and refreezing on Nordenskiöldbreen, Svalbard, using a coupled snow and energy balance model

2012 ◽  
Vol 6 (1) ◽  
pp. 211-266 ◽  
Author(s):  
W. J. J. van Pelt ◽  
J. Oerlemans ◽  
C. H. Reijmer ◽  
V. A. Pohjola ◽  
R. Pettersson ◽  
...  
Keyword(s):  
Time Series ◽  
Energy Balance ◽  
Mass Balance ◽  
Climate Sensitivity ◽  
Energy Balance Model ◽  
Balance Model ◽  
Mass Budget ◽  
Sensitivity Experiments ◽  
Temperature And Precipitation ◽  
The Impact

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 Nordenskiöldbreen, Svalbard. The model is forced with output of a 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. Output of the climate sensitivity experiments is used in combination with temperature and precipitation time-series to extend mass balance time-series in the past and the future to obtain estimates for the period 1912–2085. It is shown that including seasonality in climate change, with less pronounced summer warming, has a major impact on future mass balance and ELA estimates. Due to compensating effects, the contribution of refreezing hardly changes in a future climate.

Combining distributed glacier mass balance and ice flow models to improve projections of mass change for debris-covered Khumbu Glacier, Nepal

2021 ◽  
Author(s):  
Anya Schlich-Davies ◽  
Ann Rowan ◽  
Duncan Quincey ◽  
Andrew Ross ◽  
David Egholm
Keyword(s):  
Mass Balance ◽  
Climate Models ◽  
Flow Model ◽  
Regional Climate ◽  
Balance Model ◽  
Glacier Mass Balance ◽  
Climate Data ◽  
Ice Flow ◽  
Flow Models ◽  
Distributed Models

<p>Debris-covered glaciers in the Himalaya are losing mass more rapidly than expected. Quantifying and understanding the behaviour of these glaciers under climate change requires the use of numerical glacier models that represent the important feedbacks between debris transport, ice flow, and mass balance. However, these approaches have, so far, lacked a robust representation of the distributed mass balance forcing that is critical for making accurate simulations of ice volume change. This study forces a 3D higher-order ice flow model, with the outputs from an ensemble of distributed models of present day and future mass balance of Khumbu Glacier, Nepal. Distributed mass balance modelling, using the open access COupled Snowpack and Ice surface energy and mass balance model in PYthon (COSIPY) model (Sauter et al., 2020), was forced by three statistically downscaled climate models from the Coordinated Regional Climate Downscaling Experiment (CORDEX) project.</p><p>Climate models were selected based on their ability to reproduce observed present-day seasonality and to account for several future climate and monsoon scenarios, the latter being of particular importance for these summer-accumulation type glaciers. Two emission scenarios, RCP4.5 and RCP8.5, were also chosen to simulate glacier change to 2100. Statistical downscaling involved Quantile Mapping and Generalized Analog Regression Downscaling, and the efficacy of these approaches was informed by present day mass balance sensitivity studies. Downscaled daily climate data were trained with data from two weather stations to aid disaggregation to an hourly resolution.</p><p>The integration of the mass balance and ice flow models posed some interesting challenges. The COSIPY model was run as if Khumbu Glacier were a clean-ice glacier (with no supraglacial debris) with sub-debris ablation resolved in the ice flow model. The value of using distributed mass balance forcing is seen in the simulated present-day velocities in the Khumbu icefall, which give a better fit to remote-sensing observations than previous simulations using a simple elevation-dependent mass balance forcing. The simulated present-day glacier extent is considerably smaller than the existing glacier outline. The debris-covered tongue, known to be losing mass at an accelerating rate, is virtually absent from these results, and is indicative of a stagnant tongue that is now or very soon to be dynamically disconnected from the active upper reaches of Khumbu Glacier.</p>

scholarly journals Simulation of the historical variations in length of Unterer Grindelwaldgletscher, Switzerland

1997 ◽  
Vol 43 (143) ◽  
pp. 152-164 ◽  
Author(s):  
M. J. Schmeits ◽  
J. Oerlemans
Keyword(s):  
Mass Balance ◽  
Flow Model ◽  
Balance Model ◽  
Climatic Data ◽  
Seasonal Temperature ◽  
Mass Balance Model ◽  
Ice Flow ◽  
Historical Simulation ◽  
Temperature And Precipitation ◽  
Forcing Functions

AbstractThe historical length variations in Unterer Grindelwaldgletscher have been simulated by coupling a numerical mass-balance model to a dynamic ice-flow model. As forcing functions, we used (partly reconstructed) local climatic records, which were transformed by the mass-balance model into a mass-balance history. The ice-flow model then computes the length variations that have occurred over the course of time.In a model run from AD 1530 to the present, with both seasonal temperature and precipitation variations as forcing functions, the observed maximum length of the glacier around AD 1860 and the subsequent retreat are simulated. The observed AD 1600 maximum, however, does not show up in the simulation. This is probably due to an incorrect reconstruction of the mass balance for this period, as detailed climatic data are available only since 1865. The root-mean-square difference between the simulated and the observed front positions is 0.28 km. The simulated glacier geometry for 1987 fits the observed geometry for that year reasonably well.Because of the success of the historical simulation, an attempt is made to predict future glacier retreat on the basis of two different greenhouse-gas scenarios. For a Business-as-Usual scenario, only 29% of the 1990 volume would remain in AD 2100.

scholarly journals Mass-balance modelling of the Greenland ice sheet: a comparison of an energy-balance and a degree-day model

1996 ◽  
Vol 23 ◽  
pp. 36-45 ◽  
Author(s):  
R. S. W. van de Wal
Keyword(s):  
Energy Balance ◽  
Mass Balance ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Energy Balance Model ◽  
Balance Model ◽  
Temperature Perturbation ◽  
Degree Day

A degree-day model and an energy-balance model for the Greenland ice sheet are compared. The two models are compared at a grid with 20 km spacing. Input for both models is elevation, latitude and accumulation. The models calculate the annual ablation over the entire ice sheet. Although on the whole the two models yield similar results, depending on the tuning of the models, regional discrepancies of up to 45% occur, especially for northern Greenland. The performance of the two types of model is evaluated by comparing the model results with the sparsely available (long-term) mass-balance measurements. Results show that the energy-balance model tends to predict a more accurate mass-balance gradient with elevation than does the degree-day model. Since so little is known about the present-day climate of the ice sheet, it is more useful to consider the sensitivity of the ablation to various climate elements than to consider the actual present-day ablation. Results show that for a 1 K temperature perturbation, sea-level rise is 0.31 mm year−1 for the energy-balance model and 0.34 mm year−1 for the degree-day model. After tuning the degree-day model to a value of the ablation, equivalent to the ablation calculated by the energy-balance model, sensitivity of the degree-day model increases to 0.37 mm sea-level change per year. This means that the sensitivity of the degree-day model for a 1 K temperature perturbation is about 20% higher than the sensitivity of the energy-balance model. Another set of experiments shows that the sensitivity of the ablation is dependent on the magnitude of the temperature perturbation for the two models. Both models show an increasing sensitivity per degree for larger perturbations. The increase in the sensitivity is larger for the degree-day model than for the energy-balance model. The differences in the sensitivity are mainly concentrated in the southern parts of the ice sheet. Experiments for the Bellagio temperature scenario. 0.3°C increase in temperature per decade, leads to sea-level rise of 4.4 cm over a period of 100 years for the energy-balance model. The degree-day model predicts for the same forcing a 5.8 cm rise which is about 32% higher than the result of the energy-balance model.

Similarities and differences in the response to climate warming of two ice caps in Iceland

2009 ◽  
Vol 40 (5) ◽  
pp. 495-502 ◽  
Author(s):  
S. Guðmundsson ◽  
H. Björnsson ◽  
T. Jóhannesson ◽  
G. Aðalgeirsdóttir ◽  
F. Pálsson ◽  
...  
Keyword(s):  
Climate Change ◽  
Mass Balance ◽  
Climate Change Scenario ◽  
Flow Model ◽  
Emission Scenario ◽  
Balance Model ◽  
Change Scenario ◽  
Ice Flow ◽  
Ice Caps ◽  
Weather Parameters

The transient response to projected climate change of two ice caps in the central Icelandic highland was simulated with a vertically integrated ice-flow model coupled to a degree-day mass-balance model. The ice caps, Langjökull and Hofsjökull, are of similar size (area ∼900 km2 and volume ∼200 km3) and located only ∼30 km apart. The climate change simulations were started in 1990 from steady states corresponding to the average climate of 1981–2000 and driven with observed weather parameters until 2005. Thereafter, the forcing was according to a Nordic climate change scenario based on the IPCC B2 emission scenario. The simulations during the period 1990–2005 compare reasonably well with observations of mass-balance and glacier extent. Both ice caps are projected to essentially disappear during the next 100 to 200 years. Langjökull, which disappears within the next 150 years, shows larger mass-balance sensitivity to warming than the higher elevated Hofsjökull, where ice on the highest peaks may last over 200 years. A large proportion of the simulated runoff increase with respect to a 1981–2000 average has already taken place within the period 1990–2005. The runoff will increase further during the next 40–60 years and remain considerably higher than at present until the end of the 21st century.

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