Surface energy balance, parameterizations of boundary-layer heights and the application of resistance laws near an Antarctic Ice Shelf front

1990 ◽  
Vol 51 (1-2) ◽  
pp. 123-158 ◽  
Author(s):  
G. Heinemann ◽  
L. Rose
Keyword(s):  
Boundary Layer ◽  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Ice Shelf

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 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.

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 Surface Energy Balance and Buoyancy Response to Shallow Cumulus Shading

2014 ◽  
Vol 71 (2) ◽  
pp. 665-682 ◽  
Author(s):  
Fabienne Lohou ◽  
Edward G. Patton
Keyword(s):  
Boundary Layer ◽  
Heat Flux ◽  
Energy Balance ◽  
Surface Energy ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Surface Energy Balance ◽  
Surface Model ◽  
Entrainment Rate ◽  
Highly Nonlinear

Abstract The interactions surrounding the coupling between surface energy balance and a boundary layer with shallow cumuli are investigated using the National Center for Atmospheric Research’s large-eddy simulation code coupled to the Noah land surface model. The simulated cloudy boundary layer is based on the already well-documented and previously simulated 21 June 1997 case at the Atmospheric Radiation Measurement Southern Great Plains central facility. The surface energy balance response to cloud shading is highly nonlinear, leading to different partitioning between sensible and latent heat flux compared to the surface not impacted by cloud. The evaporative fraction increases by about 2%–3% in the presence of shallow cumuli at the regional scale but can increase by up to 30% at any individual location. As expected, the cloud’s reduction of solar irradiance largely controls the surface’s response. However, the turbulence and secondary circulations associated with the cloud dynamics increases the surface flux variability. Even though they are less than 1 km in horizontal scale, the cloud-induced surface heterogeneities impact the vertical flux of heat and moisture up to approximately 20% of the height of the subcloud layer zsl, higher than the surface layer’s typical extent. Above 0.2zsl, the cloud root tends to amplify the drying and the cooling of the subcloud layer. Near the entrainment zone, the cloud-induced latent heat flux increase and sensible heat flux decrease compensate each other with respect to total buoyancy and therefore do not significantly modify the subcloud-layer entrainment rate over large time scales.

Physical Processes

1998 ◽  
Author(s):  
T. N. Krishnamurti ◽  
H. S. Bedi ◽  
V. M. Hardiker
Keyword(s):  
Boundary Layer ◽  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Weather Prediction ◽  
Surface Fluxes ◽  
Physical Processes ◽  
Numerical Weather ◽  
Spectral Models ◽  
Heat And Moisture

In this chapter we present some of the physical processes that are used in numerical weather prediction modeling. Grid-point models, based on finite differences, and spectral models both generally treat the physical processes in the same manner. The vertical columns above the horizontal grid points (the transform grid for the spectral models) are the ones along which estimates of the effects of the physical processes are made. In this chapter we present a treatment of the planetary boundary layer, including a discussion on the surface similarity theory. Also covered is the cumulus parameterization problem in terms of the Kuo scheme and the Arakawa- Schubert sheme. Large-scale condensation and radiative transfer in clear and cloudy skies are the final topics reviewed. There are at least three types of fluxes that one deals with, namely momentum, sensible heat, and moisture. Furthermore, one needs to examine separately the land and ocean regions. In this section we present the socalled bulk aerodynamic methods as well as the similarity analysis approach for the estimation of the surface fluxes. The radiation code in a numerical weather prediction model is usually coupled to the calculation of the surface energy balance. This will be covered later in Section 8.5.6. This surface energy balance is usually carried out over land areas, where one balances the net radiation against the surface fluxes of heat and moisture for the determination of soil temperature. Over oceans, the sea-surface temperatures are prescribed where the surface energy balance is implicit. Thus it is quite apparent that what one does in the parameterization of the planetary boundary layer has to be integrated with the radiative parameterization in a consistent manner.

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.

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