Quantification of the Impact of Supraglacial Lakes and Slush on Surface Energy Balance of Ice Shelves

2020 ◽  
Author(s):  
Naomi Lefroy ◽  
Neil Arnold
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Mass Balance ◽  
Surface Energy Balance ◽  
Google Earth ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Supraglacial Lakes ◽  
Extra Energy ◽  
Energy Exchanges

<p>Despite the well-researched implications of SGL development and drainage for changes in mass balance and dynamics on Greenland, little is known about the role of energy absorption by lakes on Antarctica. Supraglacial lakes (SGLs) are prevalent features of Antarctic surface hydrology forming mainly on ice shelves (<100 m a.s.l) and efficiently conveying atmospheric energy to the ice interior (Lenaerts et al., 2017; Bell et al., 2018). SGLs on Antarctic Ice Shelves are significant for mass balance given lower surface albedo and drainage-induced collapse of fringing ice shelves and consequent increased discharge from tributary outlet glaciers (Stokes et al., 2019).</p><p>There have been few efforts to quantify the energy exchanges between SGLs, atmosphere and ice to calculate their effects on glacier ablation (Law et al., 2018), although Miles et al. (2016) find that ponds on a debris-covered mountain glacier input large amounts of energy to underlying ice. Therefore, it is proposed that ice-sheet ponds also act as a significant energy exchange surface inputting large amounts of energy to the ice.</p><p>This study aims to code a computationally efficient surface energy balance model (SEB) in Google Earth Engine Editor to quantify how much extra energy is absorbed by SGLs at the during 2019 melt season. The most prolific surface melt is associated with the Antarctic Peninsula, but several East Antarctic ice shelves experience upwards of 60 days/yr of melting (Bell et al., 2018). Near-grounding line negative mass balance of the Nivlisen Ice Shelf (70 <sup>∘</sup>S, 12 <sup>∘</sup>E) in central Dronning Maud Land, East Antarctica, is sufficient to form SGLs and will be used to test SEB accuracy.</p><p>The one-dimensional numerical energy-balance SGL model GlacierLake, developed by Law et al. (2018), will be implemented in Google Earth Engine to code for surface energy exchanges. GlacierLake is most sensitive to the proportion of shortwave radiation absorbed at the surface which indicates that it is responsive to surface energy fluxes and is useful for the purposes of this study. A variety of methods, including NDWI and Principle Components Analysis, will be evaluated for use to classify lake and slush extents.</p><p>Given that it takes 3.4 x 10<sup>5</sup> J/kg of latent heat to melt ice at 0 °C, the volume of liquid water on the Nivlisen ice shelf implies how much atmospheric energy has been transferred to the ice shelf. The modelled quantification of extra energy absorbed by lakes will be compared to the observed water volume on the Nivlisen Ice Shelf to test model accuracy.</p><p>Whilst this study will focus on the Nivlisen Ice Shelf, the SEB model may be applied at pan-Antarctic scales to calculate the ice-sheet wide extra energy absorbed by surface meltwater pooling. A precise quantification of the present impact of energy absorption by lakes on mass balance and dynamics provides a baseline to gauge how meltwater contribution could evolve under atmospheric warming.</p>

scholarly journals The influence of föhn winds on annual and seasonal surface melt on the Larsen C Ice Shelf, Antarctica

2020 ◽  
Vol 14 (11) ◽  
pp. 4165-4180
Author(s):  
Jenny V. Turton ◽  
Amélie Kirchgaessner ◽  
Andrew N. Ross ◽  
John C. King ◽  
Peter Kuipers Munneke
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Model Driven ◽  
Area Of Interest ◽  
Surface Melt ◽  
The Individual ◽  
The Impact

Abstract. Warm, dry föhn winds are observed over the Larsen C Ice Shelf year-round and are thought to contribute to the continuing weakening and collapse of ice shelves on the eastern Antarctic Peninsula (AP). We use a surface energy balance (SEB) model, driven by observations from two locations on the Larsen C Ice Shelf and one on the remnants of Larsen B, in combination with output from the Antarctic Mesoscale Prediction System (AMPS), to investigate the year-round impact of föhn winds on the SEB and melt from 2009 to 2012. Föhn winds have an impact on the individual components of the surface energy balance in all seasons and lead to an increase in surface melt in spring, summer and autumn up to 100 km away from the foot of the AP. When föhn winds occur in spring they increase surface melt, extend the melt season and increase the number of melt days within a year. Whilst AMPS is able to simulate the percentage of melt days associated with föhn with high skill, it overestimates the total amount of melting during föhn events and non-föhn events. This study extends previous attempts to quantify the impact of föhn on the Larsen C Ice Shelf by including a 4-year study period and a wider area of interest and provides evidence for föhn-related melting on both the Larsen C and Larsen B ice shelves.

scholarly journals The influence of föhn winds on annual and seasonal surface melt on the Larsen C Ice Shelf, Antarctica

2020 ◽  
Author(s):  
Jenny Victoria Turton ◽  
Amélie Kirchgaessner ◽  
Andrew N. Ross ◽  
John C. King ◽  
Peter Kuipers Munneke
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Model Driven ◽  
Area Of Interest ◽  
Surface Melt ◽  
The Individual ◽  
The Impact

Abstract. Warm, dry föhn winds are observed over the Larsen C Ice shelf year-round and are thought to contribute to the continuing weakening and collapse of ice shelves on the eastern Antarctic Peninsula. We use a surface energy balance (SEB) model, driven by observations from two locations on the Larsen C ice shelf and one on the remnants of Larsen B, in combination with output from the Antarctic Mesoscale Prediction System (AMPS), to investigate the year-round impact of föhn winds on the SEB and melt from 2009–2012. Föhn winds have an impact on the individual components of the surface energy balance in all seasons, and lead to an increase in surface melt in spring, summer and autumn up to 100 km away from the foot of the AP. When föhn winds occur in spring they increase surface melt, extend the melt season and increase the number of melt days within a year. Whilst AMPS is able to simulate the percentage of melt days associated with föhn with high skill, it overestimates the total amount of melting during föhn events and non-föhn events. This study extends previous attempts at quantifying the impact of föhn on the Larsen C ice shelf by including a four-year study period and a wider area of interest and provides evidence for föhn-related melting on both Larsen C and Larsen B ice shelves.

scholarly journals COSIPY v1.2 – An open-source coupled snowpack and ice surface energy and mass balance model

2020 ◽  
Author(s):  
Tobias Sauter ◽  
Anselm Arndt ◽  
Christoph Schneider
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Mass Balance ◽  
Surface Energy Balance ◽  
Balance Model ◽  
Surface Mass Balance ◽  
Mass Balance Model ◽  
Physical Processes ◽  
Surface Mass ◽  
Ice Surface

Abstract. Glacial changes play a key role both from a socio-economical and political, and scientific point of view. The identification and the understanding of the nature of these changes still poses fundamental challenges for climate, glacier and water research. Many studies aim to identify the climatic drivers behind the observed glacial changes using distributed surface mass and energy balance models. Distributed surface mass balance models, which translate the meteorological conditions on glaciers into local melting rates, thus offer the possibility to attribute and detect glacier mass and volume responses to changes in the climatic forcings. A well calibrated model is a suitable test-bed for sensitivity, detection and attribution analyses for many scientific applications and often serves as a tool for quantifying the inherent uncertainties. Here we present the open-source coupled snowpack and ice surface energy and mass balance model in Python COSIPY, which provides a lean, flexible and user-friendly framework for modelling distributed snow and glacier mass changes. The model has a modular structure so that the exchange of routines or parameterizations of physical processes is possible with little effort for the user. The model has a modular structure so that the exchange of routines or parameterizations of physical processes is possible with little effort for the user. The framework consists of a computational kernel, which forms the runtime environment and takes care of the initialization, the input-output routines, the parallelization as well as the grid and data structures. This structure offers maximum flexibility without having to worry about the internal numerical flow. The adaptive sub-surface scheme allows an efficient and fast calculation of the otherwise computationally demanding fundamental equations. The surface energy-balance scheme uses established standard parameterizations for radiation as well as for the energy exchange between atmosphere and surface. The schemes are coupled by solving both surface energy balance and subsurface fluxes iteratively in such that consistent surface skin temperature is returned at the interface. COSIPY uses a one-dimensional approach limited to the vertical fluxes of energy and matter but neglects any lateral processes. Accordingly, the model can be easily set up in parallel computational environments for calculating both energy balance and climatic surface mass balance of glacier surfaces based on flexible horizontal grids and with varying temporal resolution. The model is made available on a freely accessible site and can be used for non-profit purposes. Scientists are encouraged to actively participate in the extension and improvement of the model code.

scholarly journals The Impact of Föhn Winds on Surface Energy Balance During the 2010-2011 Melt Season Over Larsen C Ice Shelf, Antarctica

2017 ◽  
Vol 122 (22) ◽  
pp. 12,062-12,076 ◽  
Author(s):  
J. C. King ◽  
A. Kirchgaessner ◽  
S. Bevan ◽  
A. D. Elvidge ◽  
P. Kuipers Munneke ◽  
...  
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Ice Shelf ◽  
The Impact

scholarly journals COSIPY v1.3 – an open-source coupled snowpack and ice surface energy and mass balance model

2020 ◽  
Vol 13 (11) ◽  
pp. 5645-5662
Author(s):  
Tobias Sauter ◽  
Anselm Arndt ◽  
Christoph Schneider
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Mass Balance ◽  
Open Source ◽  
Surface Energy Balance ◽  
Balance Model ◽  
Surface Mass Balance ◽  
Mass Balance Model ◽  
Surface Mass ◽  
Ice Surface

Abstract. Glacier changes are a vivid example of how environmental systems react to a changing climate. Distributed surface mass balance models, which translate the meteorological conditions on glaciers into local melting rates, help to attribute and detect glacier mass and volume responses to changes in the climate drivers. A well-calibrated model is a suitable test bed for sensitivity, detection, and attribution analyses for many scientific applications and often serves as a tool for quantifying the inherent uncertainties. Here, we present the open-source COupled Snowpack and Ice surface energy and mass balance model in PYthon (COSIPY), which provides a flexible and user-friendly framework for modeling distributed snow and glacier mass changes. The model has a modular structure so that the exchange of routines or parameterizations of physical processes is possible with little effort for the user. The framework consists of a computational kernel, which forms the runtime environment and takes care of the initialization, the input–output routines, and the parallelization, as well as the grid and data structures. This structure offers maximum flexibility without having to worry about the internal numerical flow. The adaptive subsurface scheme allows an efficient and fast calculation of the otherwise computationally demanding fundamental equations. The surface energy balance scheme uses established standard parameterizations for radiation as well as for the energy exchange between atmosphere and surface. The schemes are coupled by solving both surface energy balance and subsurface fluxes iteratively such that consistent surface skin temperature is returned at the interface. COSIPY uses a one-dimensional approach limited to the vertical fluxes of energy and matter but neglects any lateral processes. Accordingly, the model can be easily set up in parallel computational environments for calculating both energy balance and climatic surface mass balance of glacier surfaces based on flexible horizontal grids and with varying temporal resolution. The model is made available on a freely accessible site and can be used for non-profit purposes. Scientists are encouraged to actively participate in the extension and improvement of the model code.

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 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 Analysis of meteorological data and the surface energy balance of McCall Glacier, Alaska, USA

2005 ◽  
Vol 51 (174) ◽  
pp. 451-461 ◽  
Author(s):  
E.J. Klok ◽  
M. Nolan ◽  
M.R. Van Den Broeke
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Mass Balance ◽  
Forest Fires ◽  
Surface Energy Balance ◽  
Meteorological Data ◽  
Heat Fluxes ◽  
Turbulent Heat ◽  
Net Radiation ◽  
Specific Mass

AbstractWe report on analysis of meteorological data for the period 27 May–20 August 2004, from two automatic weather stations on McCall Glacier, Alaska, USA, aimed at studying the relationship between climate and ablation. One station is located on a mountain ridge and the other in the ablation area where we also analyzed the energy balance. The weather station on the glacier measured an average temperature of 5.3°C (at 2 m height above surface) and wind speed of 3.1 m s−1 (at 3 m height). A sonic height ranger and ablation stakes indicate a specific mass balance of –1.94 ± 0.09 m w.e between 15 June and 20 August. The specific mass balance calculated from the surface energy balance, –2.06 ± 0.18 m w.e., is in close correspondence to this. The latter is the sum of 0.12 m w.e. of snowfall, 0.003 m w.e. of deposition and –2.18 m w.e. of melt. Net radiation contributes 74% of the melt energy. Compared to ablation measurements in the early 1970s, summer ablation was large. This increase is explained by a combination of a relatively higher net radiation, a lower albedo and larger turbulent heat fluxes that led to more energy being available for melting. No single meteorological variable can be isolated as being the principal reason for the high ablation, however. The lower ice albedo (0.19) is possibly due to ash deposits from forest fires.

Major Surface Melting over the Ross Ice Shelf Part II : Surface Energy Balance

2021 ◽  
Author(s):  
Xun Zou ◽  
David H. Bromwich ◽  
Alvaro Montenegro ◽  
Sheng‐Hung Wang ◽  
Lesheng Bai
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Surface Melting ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
Major Surface
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