scholarly journals Parameter uncertainty, refreezing and surface energy balance modelling at Austfonna ice cap, Svalbard, 2004-08

2013 ◽  
Vol 54 (63) ◽  
pp. 229-240 ◽  
Author(s):  
Torbjørn I. Østby ◽  
Thomas V. Schuler ◽  
Jon Ove Hagen ◽  
Regine Hock ◽  
Carleen H. Reijmer
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Model Performance ◽  
Surface Displacement ◽  
Glacier Mass Balance ◽  
Ice Cap ◽  
Physically Based ◽  
Parameter Values ◽  
Snow And Ice

AbstractWe apply a physically based coupled surface energy balance and snowpack model to a site close to the equilibrium line on Austfonna ice cap, Svalbard, over the 2004-08 melt seasons, to explain contributions to the energy available for melting and to quantify the significance of refreezing. The model is forced using in situ meteorological measurements and precipitation downscaled from ERA-Interim reanalysis. Applying a Monte Carlo approach to determine the tunable parameters of the model, we estimate the uncertainty related to the choice of parameter values. Multiple criteria are evaluated to identify well-performing parameter combinations, evaluating the model performance with respect to longwave outgoing radiation, snow and ice temperatures and surface displacement. On average, over the investigated melt seasons (1 June to 15 September) net radiation and sensible heat contributed 90 ± 2% and 10 ± 2%, respectively, to the mean energy available for melting snow and ice. The energy consumed by subsurface heat exchange reduced runoff by 15±2% in 2004 and 49±3% in 2008. Refreezing of meltwater and rain was estimated to be 0.37 ± 0.04 m w.e. a-1 on average over the five seasons, which represents a considerable reduction of mass loss during summer. Our findings suggest that refreezing potentially exerts a decisive control on glacier mass balance in persistently snow- or firn-covered areas.

The influence of large-scale atmospheric circulation on the surface energy balance of the King George Island ice cap

2001 ◽  
Vol 21 (1) ◽  
pp. 21-36 ◽  
Author(s):  
Matthias Braun ◽  
Helmut Saurer ◽  
Steffen Vogt ◽  
Jefferson Cardia Simões ◽  
Hermann Goßmann
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Atmospheric Circulation ◽  
Large Scale ◽  
Surface Energy Balance ◽  
King George Island ◽  
Ice Cap ◽  
Large Scale Atmospheric Circulation

scholarly journals Spatiotemporal variability in surface energy balance across tundra, snow and ice in Greenland

AMBIO ◽  
2017 ◽  
Vol 46 (S1) ◽  
pp. 81-93 ◽  
Author(s):  
Magnus Lund ◽  
Christian Stiegler ◽  
Jakob Abermann ◽  
Michele Citterio ◽  
Birger U. Hansen ◽  
...  
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Spatiotemporal Variability ◽  
Snow And Ice

scholarly journals Processes governing the mass balance of Chhota Shigri Glacier (Western Himalaya, India) assessed by point-scale surface energy balance measurements

2014 ◽  
Vol 8 (3) ◽  
pp. 2867-2922 ◽  
Author(s):  
M. F. Azam ◽  
P. Wagnon ◽  
C. Vincent ◽  
AL. Ramanathan ◽  
A. Mandal ◽  
...  
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Mass Balance ◽  
Summer Monsoon ◽  
Surface Energy Balance ◽  
Glacier Mass Balance ◽  
Point Scale ◽  
Monsoon Period ◽  
Chhota Shigri Glacier ◽  
Scale Surface

Abstract. Recent studies revealed that Himalayan glaciers have been shrinking at an accelerated rate since the beginning of the 21st century. However the climatic causes for this shrinkage remain unclear given that surface energy balance studies are almost nonexistent in this region. In this study, a point-scale surface energy balance analysis was performed using in-situ meteorological data from the ablation zone of Chhota Shigri Glacier over two separate periods (August 2012 to February 2013 and July to October 2013) in order to understand the response of mass balance to climate change. Energy balance numerical modeling provides quantification of the surface energy fluxes and identification of the factors affecting glacier mass balance. The computed ablation was validated by stake observations. During summer-monsoon period, net radiation was the primary component of the surface energy balance with 82% of the total heat flux which was complimented with turbulent sensible and latent heat fluxes with a share of 13% and 5%, respectively. A striking feature of energy balance is the positive turbulent latent heat flux, thus condensation or re-sublimation of moist air at the glacier surface takes place, during summer-monsoon period which is characterized by relatively high air temperature, high relative humidity and almost permanent melting surface. The impact of Indian summer monsoon on Chhota Shigri Glacier mass balance has also been assessed. This analysis demonstrates that the intensity of snowfall events during the summer-monsoon season plays a key role on surface albedo, in turn on melting, and thus is among the most important drivers controlling the annual mass balance of the glacier. Summer-monsoon air temperature, controlling the precipitation phase (rain vs. snow and thus albedo), counts, indirectly, also among the most important drivers for the glacier mass balance.

scholarly journals Surface energy balance in the ablation zone of Langfjordjøkelen, an arctic, maritime glacier in northern Norway

2014 ◽  
Vol 60 (219) ◽  
pp. 57-70 ◽  
Author(s):  
Rianne H. Giesen ◽  
Liss M. Andreassen ◽  
Johannes Oerlemans ◽  
Michiel R. Van Den Broeke
Keyword(s):  
Energy Balance ◽  
Solar Radiation ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Longwave Radiation ◽  
Heat Fluxes ◽  
Positive Contribution ◽  
Ablation Zone ◽  
Ice Cap ◽  
Southern Norway

AbstractGlaciers in northern and southern Norway are subject to different daily and seasonal cycles of incoming solar radiation, which is presumably reflected in the importance of net solar radiation in their surface energy balance. We present a 3 year continuous record from an automatic weather station in the ablation zone of the ice cap Langfjordjøkelen, one of the most northerly glaciers of mainland Norway. Despite its location at 70º N, Langfjordjøkelen was found to have a maritime climate, with an annual mean air temperature of –1.08C, frequent cloud cover and end-of-winter snow depths over 3 m in all three years. The main melt season was May–October, but occasional melt events occurred on warm, cloudy winter days. Net solar and longwave radiation together accounted for 58% of the melt energy, with a positive contribution by net longwave radiation (7%). The sensible and latent heat fluxes supplied the remainder of the melt energy. Cloud optical thickness over Langfjordjøkelen was larger than on two glaciers in southern Norway, especially in the summer months. This resulted in a smaller contribution of net solar radiation to surface melt on Langfjordjøkelen; the effect of the higher latitude on net solar radiation was found to be small.

Surface energy balance of Bayi Ice Cap in the middle of Qilian Mountains, China

2018 ◽  
Vol 15 (6) ◽  
pp. 1229-1240 ◽  
Author(s):  
Wen-wu Qing ◽  
Chun-tan Han ◽  
Jun-feng Liu
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Qilian Mountains ◽  
Ice Cap

scholarly journals Processes governing the mass balance of Chhota Shigri Glacier (western Himalaya, India) assessed by point-scale surface energy balance measurements

2014 ◽  
Vol 8 (6) ◽  
pp. 2195-2217 ◽  
Author(s):  
M. F. Azam ◽  
P. Wagnon ◽  
C. Vincent ◽  
AL. Ramanathan ◽  
V. Favier ◽  
...  
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Surface Energy ◽  
Mass Balance ◽  
Summer Monsoon ◽  
Surface Energy Balance ◽  
Glacier Mass Balance ◽  
Point Scale ◽  
Chhota Shigri Glacier ◽  
Scale Surface

Abstract. Some recent studies revealed that Himalayan glaciers were shrinking at an accelerated rate since the beginning of the 21st century. However, the climatic causes for this shrinkage remain unclear given that surface energy balance studies are almost nonexistent in this region. In this study, a point-scale surface energy balance analysis was performed using in situ meteorological data from the ablation zone of Chhota Shigri Glacier over two separate periods (August 2012 to February 2013 and July to October 2013) in order to understand the response of mass balance to climatic variables. Energy balance numerical modelling provides quantification of the surface energy fluxes and identification of the factors affecting glacier mass balance. The model was validated by comparing the computed and observed ablation and surface temperature data. During the summer-monsoon period, net radiation was the primary component of the surface energy balance accounting for 80 % of the total heat flux followed by turbulent sensible (13%), latent (5%) and conductive (2%) heat fluxes. A striking feature of the energy balance is the positive turbulent latent heat flux, suggesting re-sublimation of moist air at the glacier surface, during the summer-monsoon characterized by relatively high air temperature, high relative humidity and a continual melting surface. The impact of the Indian Summer Monsoon on Chhota Shigri Glacier mass balance has also been assessed. This analysis demonstrates that the intensity of snowfall events during the summer-monsoon plays a key role on surface albedo (melting is reduced in the case of strong snowfalls covering the glacier area), and thus is among the most important drivers controlling the annual mass balance of the glacier. The summer-monsoon air temperature, controlling the precipitation phase (rain versus snow and thus albedo), counts, indirectly, also among the most important drivers.

scholarly journals Assessing the uncertainty of glacier mass-balance simulations in the European Arctic based on variance decomposition

2015 ◽  
Vol 8 (12) ◽  
pp. 3911-3928 ◽  
Author(s):  
T. Sauter ◽  
F. Obleitner
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Critical Parameters ◽  
Wave Radiation ◽  
Glacier Mass Balance ◽  
Model Output ◽  
Long Wave ◽  
Sensitivity Pattern ◽  
Long Wave Radiation

Abstract. State-of-the-art numerical snowpack models essentially rely on observational data for initialization, forcing, parametrization, and validation. Such data are available in increasing amounts, but the propagation of related uncertainties in simulation results has received rather limited attention so far. Depending on their complexity, even small errors can have a profound effect on simulations, which dilutes our confidence in the results. This paper aims at quantification of the overall and fractional contributions of some archetypical measurement uncertainties on snowpack simulations in arctic environments. The sensitivity pattern is studied at two sites representing the accumulation and ablation area of the Kongsvegen glacier (Svalbard), using the snowpack scheme Crocus. The contribution of measurement errors on model output variance, either alone or by interaction, is decomposed using global sensitivity analysis. This allows one to investigate the temporal evolution of the fractional contribution of different factors on key model output metrics, which provides a more detailed understanding of the model's sensitivity pattern. The analysis demonstrates that the specified uncertainties in precipitation and long-wave radiation forcings had a strong influence on the calculated surface-height changes and surface-energy balance components. The model output sensitivity patterns also revealed some characteristic seasonal imprints. For example, uncertainties in long-wave radiation affect the calculated surface-energy balance throughout the year at both study sites, while precipitation exerted the most influence during the winter and at the upper site. Such findings are valuable for identifying critical parameters and improving their measurement; correspondingly, updated simulations may shed new light on the confidence of results from snow or glacier mass- and energy-balance models. This is relevant for many applications, for example in the fields of avalanche and hydrological forecasting.

scholarly journals Using climate reanalysis data in conjunction with multi-temporal satellite thermal imagery to derive supraglacial debris thickness changes from energy-balance modelling

2021 ◽  
pp. 1-19
Author(s):  
Rebecca L. Stewart ◽  
Matthew Westoby ◽  
Francesca Pellicciotti ◽  
Ann Rowan ◽  
Darrel Swift ◽  
...  
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Current Knowledge ◽  
Meteorological Data ◽  
Reanalysis Data ◽  
Balance Model ◽  
Thermal Imagery ◽  
Thickness Estimation ◽  
Miage Glacier

Abstract Surface energy-balance models are commonly used in conjunction with satellite thermal imagery to estimate supraglacial debris thickness. Removing the need for local meteorological data in the debris thickness estimation workflow could improve the versatility and spatiotemporal application of debris thickness estimation. We evaluate the use of regional reanalysis data to derive debris thickness for two mountain glaciers using a surface energy-balance model. Results forced using ERA-5 agree with AWS-derived estimates to within 0.01 ± 0.05 m for Miage Glacier, Italy, and 0.01 ± 0.02 m for Khumbu Glacier, Nepal. ERA-5 data were then used to estimate spatiotemporal changes in debris thickness over a ~20-year period for Miage Glacier, Khumbu Glacier and Haut Glacier d'Arolla, Switzerland. We observe significant increases in debris thickness at the terminus for Haut Glacier d'Arolla and at the margins of the expanding debris cover at all glaciers. While simulated debris thickness was underestimated compared to point measurements in areas of thick debris, our approach can reconstruct glacier-scale debris thickness distribution and its temporal evolution over multiple decades. We find significant changes in debris thickness over areas of thin debris, areas susceptible to high ablation rates, where current knowledge of debris evolution is limited.

scholarly journals Application of an improved surface energy balance model to two large valley glaciers in the St. Elias Mountains, Yukon

2020 ◽  
pp. 1-16
Author(s):  
Tim Hill ◽  
Christine F. Dow ◽  
Eleanor A. Bash ◽  
Luke Copland
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Shortwave Radiation ◽  
Balance Model ◽  
Landsat 8 ◽  
Glacier Surface ◽  
Ice Dynamics ◽  
Surface Melt

Abstract Glacier surficial melt rates are commonly modelled using surface energy balance (SEB) models, with outputs applied to extend point-based mass-balance measurements to regional scales, assess water resource availability, examine supraglacial hydrology and to investigate the relationship between surface melt and ice dynamics. We present an improved SEB model that addresses the primary limitations of existing models by: (1) deriving high-resolution (30 m) surface albedo from Landsat 8 imagery, (2) calculating shadows cast onto the glacier surface by high-relief topography to model incident shortwave radiation, (3) developing an algorithm to map debris sufficiently thick to insulate the glacier surface and (4) presenting a formulation of the SEB model coupled to a subsurface heat conduction model. We drive the model with 6 years of in situ meteorological data from Kaskawulsh Glacier and Nàłùdäy (Lowell) Glacier in the St. Elias Mountains, Yukon, Canada, and validate outputs against in situ measurements. Modelled seasonal melt agrees with observations within 9% across a range of elevations on both glaciers in years with high-quality in situ observations. We recommend applying the model to investigate the impacts of surface melt for individual glaciers when sufficient input data are available.

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