GLACIOLOGY

The majority of ice on the earth is contained on ice sheets. They are a type of glaciers which are currently the largest of glaciers. The volume of ice sheets changes continuously due to the addition of snow and ice at the base or terminus. Hence, glaciers have dynamic characterizes, which make it possible to compare and contrast the drainage systems of Haut Glacier d’Arolla and the Greenland Ice Sheet.

From geolocation and physical features contrasting perspective, the Greenland Ice Sheet (GrIS) is polythermal (Greve, 1997, p.901). The ice sheet exists in polar, sub-polar, temperate and sub-temperate at different regions in at different times, but it is generally windy and dry (Lenaerts, Medley, Broeke and Wouters, 2019, p. 377). Also, the GrIS covers an area of 1.7 million km² and has basal water forms of about one meter wide, and three centimetres deep. (Bowling, Livingstone, Sole and Chu, 2019, p. 2). In contrast, the Haut Glacier d’Arolla (HGA) covers 6.3 km², in the Swiss Alps (Richards et al., 1996, p.480). It has a basin feeding to the north and has an elevation of about 2550 to 3500 meters above sea level. They are warmer than the GrIs and hence more subglacial underground water sources (Bartholomew et al., 2010, p. 409).

A further contrast between the Haut Glacier d’Arolla (HGA) and the GrIS is revealed in the flow of water within the systems. Notably, the flow of water is dependent on the potential difference due to the sloping features of the glacier. The HGA is generally topographically higher than GrIS (Nienow, Sole, Slater and Cowton, 2017, p.332). Hence there is more water flows in the former than the latter. Also, although HGA has a higher rate of flow, the GrIS have been found to have four subglacial lakes (Bowling, Livingstone, Sole and Chu, 2019, p.1). Since there is no recorded change in pathways for subglacial water flow in HGA, it appears that the topographic conditions of GrIS are changing faster than of HGA. Lastly, the water flow in HGA has been found at the proximity of the ice margin. In GrIS, the water flow to the ice margin is less significant, due to the formation of subglacial lakes and its size in comparison to HGA (Smith et al., 2015, p.1002).

Concerning similarities, both HGA and GrIS, are well comparable in seasonal evolution. The evolution of both ice sheets cycles between the meeting and freezing seasons. During winter, both ice sheets experience enhanced sliding and reduced basal tractions. These experiences are caused by overwhelming surface melting, which increases water pressure (Hoffman et al., 2016, p.2). Also, the melting tales place in inefficient waterways that are characterized by a long, inefficient pathway. During the melt season, GrIS surface melt increases, the water-ice friction reduces, and the melt pathways are more efficient (Nienow, Sole, Slater and Cowton, 2017, P.333).

In the same way, the HGA manifest reversed inefficiency during the melting season unlike during the freezing season. According to Nienow, Sharp and Willis (1998, p.404), the seasonal variation for HGA is such that at one season, the meltwater ways are constrained in time and space, and in another, they are not. Also, subglacial drainage is possible to occur on any part viable part of the ice sheets, as long as the basal temperature has reached the melting point (Pattyn, 2010). Hence, the flow of meltwater in both HGA and GrIS is influenced by temperate conditions in the same way.

Both HGA and GrIS have comparable feeding systems and atmospheric flow. In both ice sheets, the subglacial macroporous drainage systems occur through the supraglacial and englacial structures (Hoffman et al., 2016, p.9; Bowling, Livingstone, Sole and Chu, 2019, p.2). The surface waters ways on the surface streams and moulins in which water flows to enlarged surfaces undergo transition. Also, both ice sheets experienced similar atmospheric flow, regarding the various topographies they are formed. For instance, a relatively raised HGA or GrIS to approximately 100 km in length may lead to orographic precipitation (Lenaerts, Medley, Broeke and Wouters, 2019, p.382). In other studies, the atmospheric flow over the glacial impacts both ice sheets the same way (Richards et al., 1996, p.486). For instance, the impact of atmospheric flow on either sheet depends on topographic roughness and dimensions.

To sum up, HGA and GrIS are comparable through physical features and processes. Both exhibit different geolocation and features. They are similar in their evolution cycles, and both have comparable feeding systems and atmospheric flow.

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References

Bartholomew, I., Nienow, P., Mair, D., Hubbard, A., King, M. and Sole, A., 2010. Seasonal evolution of subglacial drainage and acceleration in a Greenland outlet glacier. Nature Geoscience, 3(6), pp.408-411.

Bowling, J., Livingstone, S., Sole, A. and Chu, W., 2019. Distribution and dynamics of Greenland subglacial lakes. Nature Communications, 10(1).

Greve, R., 1997. Application of a Polythermal Three-Dimensional Ice Sheet Model to the Greenland Ice Sheet: Response to Steady-State and Transient Climate Scenarios. Journal of Climate, 10(5), pp.901-918.

Hoffman, M., Andrews, L., Price, S., Catania, G., Neumann, T., Lüthi, M., Gulley, J., Ryser, C., Hawley, R. and Morriss, B., 2016. Greenland subglacial drainage evolution regulated by weakly connected regions of the bed. Nature Communications, 7(1).

Lenaerts, J., Medley, B., Broeke, M. and Wouters, B., 2019. Observing and Modeling Ice Sheet Surface Mass Balance. Reviews of Geophysics, 57(2), pp.376-420.

Nienow, P., Sole, A., Slater, D. and Cowton, T., 2017. Recent Advances in Our Understanding of the Role of Meltwater in the Greenland Ice Sheet System. Current Climate Change Reports, 3(4), pp.330-344.

Pattyn, F., 2010. Antarctic subglacial conditions inferred from a hybrid ice sheet/ice stream model. Earth and Planetary Science Letters, 295(3-4), pp.451-461.

Richards, K., Sharp, M., Arnold, N., Gurnell, A., Clark, M., Tranter, M., Nienow, P., Brown, G., Willis, I. And Lawson, W., 1996. An Integrated Approach To Modelling Hydrology And Water Quality In Glacierized Catchments. Hydrological Processes, 10(4), pp.479-508.

Smith, L., Chu, V., Yang, K., Gleason, C., Pitcher, L., Rennermalm, A., Legleiter, C., Behar, A., Overstreet, B., Moustafa, S., Tedesco, M., Forster, R., LeWinter, A., Finnegan, D., Sheng, Y. and Balog, J., 2015. Efficient meltwater drainage through supraglacial streams and rivers on the southwest Greenland ice sheet. Proceedings of the National Academy of Sciences, 112(4), pp.1001-1006.