11:15 AM - 11:30 AM
[MZZ49-03] Distribution and seasonal evolutions of supraglacial lakes around Lützow-Holm Bay, East Antarctica
Keywords:supraglacial lakes, remote sensing
The loss/melting of the Antarctic ice sheet is evident in the Antarctic Peninsula, and its contribution to sea-level rise is a matter of concern. A recent study using satellite imagery with remote sensing technology revealed the development of supraglacial lakes on the margins of the Antarctic ice sheet, including the relatively cool East Antarctica (Kingslake et al., 2017; Stokes et al., 2019). And melting in East Antarctica has also attracted attention. However, detailed studies of seasonal evolutions in the distribution of lakes in East Antarctica are limited to a few ice shelves and glaciers (Langley et al., 2016; Moussavi et al.). This study reveals seasonal evolutions in the extent of supraglacial lakes at the Shirase and the Langhovde Glaciers in Queen Maud Land, East Antarctica.
We used Landsat 8 and Sentinel 2 satellite imagery from 2017 to 2020. We analyzed Normalized Differential Water Index (NDWI) to identify the supraglacial lakes of the Shirase and the Langhovde glaciers around Lützow-Holm Bay. The geographic distribution of the lakes was then evaluated using the digital elevation model of bedmap2 (Fretwell et al., 2013). The surface temperature was also calculated using Landsat 8 satellite imagery. We used the air temperature and total solar irradiance from the data at the Syowa Station and examined the relationship with the seasonal evolutions of supraglacial lakes.
Supraglacial lakes were identified at the Shirase Glacier and the Langhovde Glacier from November to February. Supraglacial lakes were mainly distributed at the ice sheet's margins, at low elevations (<100 m), and inland up to 25 km from the coastline. However, they also occurred at above 700 m and inland 30 km from the coastline. In addition, 80% of the lakes were located where the surface temperature was between -4.0℃ and -3.0℃, suggesting that supraglacial lakes can exist even when the surface temperature is below freezing.
We also observed that the supraglacial lakes began to form in late November, expanded in late December and early January, peaked in January, and shrank in late February. We compared the temperature and total solar irradiance at the Syowa Station with the seasonal evolutions of the supraglacial lake on the Langhovde Glacier. The results showed that the area of the supraglacial lakes did not necessarily increase when only one of the temperatures and total solar irradiance was high but tended to increase when both were high. Conversely, when both temperature and solar irradiance were low, the lake's total area would be small. It suggests that both high temperature and high total solar irradiance are necessary for the formation of supraglacial lakes. More and more supraglacial lakes may form in the future due to global warming.
We used Landsat 8 and Sentinel 2 satellite imagery from 2017 to 2020. We analyzed Normalized Differential Water Index (NDWI) to identify the supraglacial lakes of the Shirase and the Langhovde glaciers around Lützow-Holm Bay. The geographic distribution of the lakes was then evaluated using the digital elevation model of bedmap2 (Fretwell et al., 2013). The surface temperature was also calculated using Landsat 8 satellite imagery. We used the air temperature and total solar irradiance from the data at the Syowa Station and examined the relationship with the seasonal evolutions of supraglacial lakes.
Supraglacial lakes were identified at the Shirase Glacier and the Langhovde Glacier from November to February. Supraglacial lakes were mainly distributed at the ice sheet's margins, at low elevations (<100 m), and inland up to 25 km from the coastline. However, they also occurred at above 700 m and inland 30 km from the coastline. In addition, 80% of the lakes were located where the surface temperature was between -4.0℃ and -3.0℃, suggesting that supraglacial lakes can exist even when the surface temperature is below freezing.
We also observed that the supraglacial lakes began to form in late November, expanded in late December and early January, peaked in January, and shrank in late February. We compared the temperature and total solar irradiance at the Syowa Station with the seasonal evolutions of the supraglacial lake on the Langhovde Glacier. The results showed that the area of the supraglacial lakes did not necessarily increase when only one of the temperatures and total solar irradiance was high but tended to increase when both were high. Conversely, when both temperature and solar irradiance were low, the lake's total area would be small. It suggests that both high temperature and high total solar irradiance are necessary for the formation of supraglacial lakes. More and more supraglacial lakes may form in the future due to global warming.