scholarly journals The surface energy balance of Austre Lovénbreen, Svalbard, during the ablation period in 2014

2021 ◽  
Vol 40 ◽  
Author(s):  
Xiaowei Zou ◽  
Minghu Ding ◽  
Weijun Sun ◽  
Diyi Yang ◽  
Weigang Liu ◽  
...  
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Albedo ◽  
Surface Energy Balance ◽  
Meteorological Data ◽  
Longwave Radiation ◽  
Heat Sinks ◽  
Shortwave Radiation ◽  
Balance Model ◽  
Glacier Surface

The ability to simulate the surface energy balance is key to studying land–atmosphere interactions; however, it remains a weakness in Arctic polar sciences. Based on the analysis of meteorological data from 1 June to 30 September 2014 from an automatic weather station on the glacier Austre Lovénbreen, near Ny–Ålesund, Svalbard, we established a surface energy balance model to simulate surface melt. The results reveal that the net shortwave radiation accounts for 87% (39 W m–2) of the energy sources, and is controlled by cloud cover and surface albedo. The sensible heat equals 6 W m–2 and is a continuous energy source at the glacier surface. Net longwave radiation and latent heat account for 31% and 5% of heat sinks, respectively. The simulated summer mass balance equals –793 mm w.e., agreeing well with the observation by an ultrasonic ranger.

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.

scholarly journals Surface Energy Balance Sensitivity to Meteorological Variability on Haig Glacier, Canadian Rocky Mountains

2016 ◽  
Author(s):  
S. Ebrahimi ◽  
S. J. Marshall
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Rocky Mountains ◽  
Surface Albedo ◽  
Surface Energy Balance ◽  
Specific Humidity ◽  
Shortwave Radiation ◽  
Interannual Variations ◽  
Canadian Rocky Mountains ◽  
Glacier Surface

Abstract. Energy exchanges between the atmosphere and the glacier surface control the net energy available for snow and ice melt. Meteorological and glaciological observations are not always available to measure glacier energy and mass balance directly, so models of energy balance processes are often necessary to understand glacier response to meteorological variability and climate change. This paper explores the theoretical and empirical response of a mid-latitude glacier in the Canadian Rocky Mountains to the daily and interannual variations in the meteorological parameters that govern the surface energy balance. The model's reference conditions are based on 11 years of in situ observations from an automatic weather station at an elevation of 2660 m, in the upper ablation area of Haig Glacier. We use an energy balance model to run sensitivity tests to perturbations in temperature, specific humidity, wind speed, incoming shortwave radiation, and glacier surface albedo. The variables were perturbed one at a time for the duration of the glacier melt season, May to September, for the years 2002–2012. The experiments indicate that summer melt has the strongest sensitivity to interannual variations in incoming shortwave radiation, albedo, and temperature, in that order. To explore more realistic scenarios where meteorological variables and internal feedbacks such as the surface albedo co-evolve, we use the same perturbation approach using meteorological forcing from the North American Regional Reanalysis (NARR) over the period 1979–2014. These experiments provide an estimate of historical variability in Haig Glacier surface energy balance an d melt for years prior to our observational study. The methods introduced in this paper provide a methodology that can be employed in distributed energy balance modelling at regional scales. They also provide the foundation for theoretical framework that can be adapted to compare the climatic sensitivity of glaciers in different climate regimes, e.g., polar, maritime, or tropical environments.

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 Reconnaissance Study of glacier energy balance in North Greenland, 1993–94

1998 ◽  
Vol 44 (147) ◽  
pp. 239-247 ◽  
Author(s):  
Roger J. Braithwaite ◽  
Thomas Konzelmann ◽  
Christoph Marty ◽  
Ole B. Olesen
Keyword(s):  
Energy Balance ◽  
Field Experiments ◽  
Longwave Radiation ◽  
Heat Fluxes ◽  
Shortwave Radiation ◽  
Balance Model ◽  
Conductive Heat ◽  
Glacier Surface ◽  
West Greenland ◽  
North Greenland

AbstractReconnaissance energy-balance studies were made for the first time at two sites in North Greenland to compare with conditions in West Greenland. The field experiments were planned to save weight because it is expensive to operate in North Greenland. The larger energy components (incoming radiation and ablation) were measured for 55 days altogether, and the smaller components were evaluated by indirect methods, e.g. turbulent fluxes are calculated from air temperature, humidity and wind speed, to save the weight of instruments. The energy-balance model is “tuned" by choosing surface roughness and albedo to reduce the mean error between measured ablation and modelled daily melting. The error standard deviation for ablation is only ± 5 kg m−2d−1’, which is much lower than found in West Greenland, due to better instruments and modelling in the present study. Net radiation is the main energy source for melting in North Greenland but ablation is relatively low because sublimation and conductive-heat fluxes use energy that would otherwise be available for melting. There is a strong diurnal variation in ablation, mainly forced by variations in shortwave radiation and reinforced by nocturnal cooling of the ice surface by outgoing longwave radiation and sublimation. The model frequently predicts a frozen glacier surface at night even when air temperatures are positive.

scholarly journals Reconnaissance Study of glacier energy balance in North Greenland, 1993–94

1998 ◽  
Vol 44 (147) ◽  
pp. 239-247 ◽  
Author(s):  
Roger J. Braithwaite ◽  
Thomas Konzelmann ◽  
Christoph Marty ◽  
Ole B. Olesen
Keyword(s):  
Energy Balance ◽  
Field Experiments ◽  
Longwave Radiation ◽  
Heat Fluxes ◽  
Shortwave Radiation ◽  
Balance Model ◽  
Conductive Heat ◽  
Glacier Surface ◽  
West Greenland ◽  
North Greenland

AbstractReconnaissance energy-balance studies were made for the first time at two sites in North Greenland to compare with conditions in West Greenland. The field experiments were planned to save weight because it is expensive to operate in North Greenland. The larger energy components (incoming radiation and ablation) were measured for 55 days altogether, and the smaller components were evaluated by indirect methods, e.g. turbulent fluxes are calculated from air temperature, humidity and wind speed, to save the weight of instruments. The energy-balance model is “tuned" by choosing surface roughness and albedo to reduce the mean error between measured ablation and modelled daily melting. The error standard deviation for ablation is only ± 5 kg m −2 d−1’, which is much lower than found in West Greenland, due to better instruments and modelling in the present study. Net radiation is the main energy source for melting in North Greenland but ablation is relatively low because sublimation and conductive-heat fluxes use energy that would otherwise be available for melting. There is a strong diurnal variation in ablation, mainly forced by variations in shortwave radiation and reinforced by nocturnal cooling of the ice surface by outgoing longwave radiation and sublimation. The model frequently predicts a frozen glacier surface at night even when air temperatures are positive.

scholarly journals The secret life of ice sails

2017 ◽  
Vol 63 (242) ◽  
pp. 1049-1062 ◽  
Author(s):  
GEOFFREY W. EVATT ◽  
CHRISTOPH MAYER ◽  
AMY MALLINSON ◽  
I. DAVID ABRAHAMS ◽  
MATTHIAS HEIL ◽  
...  
Keyword(s):  
Heat Flux ◽  
Sensitivity Analysis ◽  
Steady State ◽  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Sensible Heat Flux ◽  
Balance Model ◽  
Sensible Heat ◽  
Glacier Surface

ABSTRACTWe present the first dedicated study into the phenomenon of ice sails. These are clean ice structures that protrude from the surface of a small number of debris-covered glaciers and can grow to heights of over 25 m. We draw together what is known about them from the academic/exploration literature and then analyse imagery. We show here that ice sails can develop by one of two mechanisms, both of which require clean ice to become surrounded by debris-covered ice, where the debris layer is shallow enough for the ice beneath it to melt faster than the clean ice. Once formed, ice sails can persist for decades, in an apparently steady state, before debris layer thickening eventually causes a reversal in the relative melt rates and the ice sails decay to merge back with the surrounding glacier surface. We support our image-based analysis with a surface energy-balance model and show that it compares well with available observations from Baltoro Glacier in the Karakoram. A sensitivity analysis of the model is performed and confirms the results from our empirical study that ice sails require a relatively high evaporative heat flux and/or a relatively low sensible heat flux in order to exist.

scholarly journals The role of radiation penetration in the energy budget of the snowpack at Summit, Greenland

2009 ◽  
Vol 3 (2) ◽  
pp. 155-165 ◽  
Author(s):  
P. Kuipers Munneke ◽  
M. R. van den Broeke ◽  
C. H. Reijmer ◽  
M. M. Helsen ◽  
W. Boot ◽  
...  
Keyword(s):  
Energy Balance ◽  
Model Simulation ◽  
Longwave Radiation ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Shortwave Radiation ◽  
Balance Model ◽  
Radiative Transfer Model ◽  
Transfer Model

Abstract. Measurements of the summer surface energy balance at Summit, Greenland, are presented (8 June–20 July 2007). These measurements serve as input to an energy balance model that searches for a surface temperature for which closure of all energy terms is achieved. A good agreement between observed and modelled surface temperatures was found, with an average difference of 0.45°C and an RMSE of 0.85°C. It turns out that penetration of shortwave radiation into the snowpack plays a small but important role in correctly simulating snow temperatures. After 42 days, snow temperatures in the first meter are 3.6–4.0°C higher compared to a model simulation without radiation penetration. Sensitivity experiments show that these results cannot be reproduced by tuning the heat conduction process alone, by varying snow density or snow diffusivity. We compared the two-stream radiation penetration calculations with a sophisticated radiative transfer model and discuss the differences. The average diurnal cycle shows that net shortwave radiation is the largest energy source (diurnal average of +61 W m−2), net longwave radiation the largest energy sink (−42 W m−2). On average, subsurface heat flux, sensible and latent heat fluxes are the remaining, small heat sinks (−5, −5 and −7 W m−2, respectively), although these are more important on a subdaily timescale.

scholarly journals Daily Actual Evapotranspiration Estimation in a Mediterranean Ecosystem from Landsat Observations Using SEBAL Approach

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 189
Author(s):  
Hassan Awada ◽  
Simone Di Prima ◽  
Costantino Sirca ◽  
Filippo Giadrossich ◽  
Serena Marras ◽  
...  
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Actual Evapotranspiration ◽  
Shortwave Radiation ◽  
Balance Model ◽  
Mediterranean Ecosystem ◽  
Acquisition Time ◽  
Natural Ecosystem ◽  
Evaporative Fraction

Quantifying actual evapotranspiration (ETa) over natural vegetation is crucial in evaluating the water status of ecosystems and the water-use patterns in local or regional hydrological basins. Remote sensing-based surface energy balance models have been used extensively for estimating ETa in agro-environments; however, the application of these models to natural ecosystems is still limited. The surface energy balance algorithm for land (SEBAL) physical-based surface energy balance model was applied to estimate the actual evapotranspiration over a heterogeneous coverage of Mediterranean maquis in a natural reserve in Sardinia, Italy. The model was applied on 19 Landsat 5 and 8 images from 2009 to 2014, and the results were compared to the data of a micrometeorological station with eddy covariance flux measurements. Comparing the SEBAL-based evaporative fraction (ΛS) to the corresponding tower-derived evaporative fractions (ΛT) showed good flux estimations in the Landsat overpass time (Coefficient of determination R2 = 0.77, root mean square error RMSE = 0.05 and mean absolute error MAE = 0.076). Three methods were evaluated for upscaling instantaneous latent heat flux (λE) to daily actual evapotranspiration (ETa,D). The upscaling methods use the evaporative fraction (Λ), the reference evapotranspiration fraction (EFr) and the ratio of daily to instantaneous incoming shortwave radiation (Rs24/Rsi) as upscaling factors under the hypothesis of diurnal self-preservation. A preliminary analysis performed using only in-situ measured data demonstrated that the three factors were relatively self-preserved during the daytime, and can yield good ETa,D estimations, particularly when obtained at near the Landsat scene acquisition time (≈10:00 UTC). The upscaling factors obtained from SEBAL retrieved instantaneous fluxes, and some ancillary measured meteorological data were used to upscale SEBAL-estimated instantaneous actual λ to daily ET. The Λ EFr and Rs24/Rsi methods on average overestimated the measured ETa,D by nearly 20, 61 and 18%, respectively. The performance of the Λ and Rs24/Rsi methods was considered satisfactory, bearing in mind the high variable ground cover and the inherent variability of the biome composition, which cannot be properly represented in the Landsat moderate spatial resolution. In this study, we tested the potential of the SEBAL model application in a complex natural ecosystem. This modeling approach will be used to represent the spatial dynamics of ET, which will be integrated into further environmental and hydrological applications.

scholarly journals A distributed surface energy-balance model for a small valley glacier. I. Development and testing for Haut Glacier d’ Arolla, Valais, Switzerland

1996 ◽  
Vol 42 (140) ◽  
pp. 77-89 ◽  
Author(s):  
N.S. Arnold ◽  
I.C. Willis ◽  
M.J. Sharp ◽  
K.S. Richards ◽  
W.J. Lawson
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Correlation Coefficients ◽  
Energy Balance Model ◽  
Balance Model ◽  
Glacier Surface ◽  
Snow Line ◽  
Digital Elevation ◽  
Elevation Model

AbstractThis paper describes the development and testing of a distributed surface energy-balance model used to calculate rates of surface melting at Haut Glacier d’Arolla, Valais, Switzerland. The model uses a digital elevation model (DEM) of the glacier surface and surrounding topography together with meterological data collected at a site in front of the glacier to determine hourly or daily totals of the energy-balance components and hence of melting over the entire surface of the glacier with a spatial resolution of 20 m. The model can also be used to determine temporal and spatial variations in snow depth, snow-line position and glacier surface albedo. Calculations from the model are compared with observations made along the glacier centre line 1990, and in general the model performs very well. The correlation coefficients between calculated and measured snow-line elevation, albedo and ablation are 0.99, 0.85 and 0.81, respectively. The main source of error between modelled and measured values of these variables is probably inadequacies in the parameterization of albedo used in the model.

scholarly journals A distributed surface energy-balance model for a small valley glacier. I. Development and testing for Haut Glacier d’ Arolla, Valais, Switzerland

1996 ◽  
Vol 42 (140) ◽  
pp. 77-89 ◽  
Author(s):  
N.S. Arnold ◽  
I.C. Willis ◽  
M.J. Sharp ◽  
K.S. Richards ◽  
W.J. Lawson
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Correlation Coefficients ◽  
Energy Balance Model ◽  
Balance Model ◽  
Glacier Surface ◽  
Snow Line ◽  
Digital Elevation ◽  
Elevation Model

AbstractThis paper describes the development and testing of a distributed surface energy-balance model used to calculate rates of surface melting at Haut Glacier d’Arolla, Valais, Switzerland. The model uses a digital elevation model (DEM) of the glacier surface and surrounding topography together with meterological data collected at a site in front of the glacier to determine hourly or daily totals of the energy-balance components and hence of melting over the entire surface of the glacier with a spatial resolution of 20 m. The model can also be used to determine temporal and spatial variations in snow depth, snow-line position and glacier surface albedo. Calculations from the model are compared with observations made along the glacier centre line 1990, and in general the model performs very well. The correlation coefficients between calculated and measured snow-line elevation, albedo and ablation are 0.99, 0.85 and 0.81, respectively. The main source of error between modelled and measured values of these variables is probably inadequacies in the parameterization of albedo used in the model.

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