[A-CG46] Science in the Arctic Region

[ACG46-P06] Seasonal changes in stripe patterns in dark regions on the southwestern Greenland Ice Sheet analyzed with Sentinel-2 satellite images

*Akane Uruma¹, Nozomu Takeuchi¹ (1.Chiba University)

The recent decline of surface albedo of snow and ice is a major contributor to the increase of surface melting of the Greenland Ice Sheet. One of the causes of this albedo decline is the expansion of the bare ice areas due to earlier melting of winter snow cover. In addition, the expansion of dark ice regions in the bare ice area (dark region) is also the cause of the recent albedo reduction. The dark regions are composed of stripe patterns perpendicular to the direction of glacier flow. However, the relationship between the formation of these stripe pattens and expansion of dark regions is not yet fully understood. In this study, we analyzed the seasonal changes in stripe patterns in dark regions on the southwestern Greenland Ice Sheet using Sentinel-2 satellite images acquired from June to August in 2019. The analysis showed that the overall mean surface reflectance in the study areas decreased from June to late July and increased in August. The correlation between the surface reflectance and meteorological data suggests that this change is due to decay and development of the weathering crust caused by the meteorological conditions. The analysis of seasonal changes in surface reflectance showed that the decrease in surface reflectance in July was different among the surfaces. The area between dark and light stripes showed the largest decrease of the reflectance. Additionally, the thickness and curve patterns of the stripes also changed seasonally. These results suggest that the changes in surface reflectance in bare ice area is associated not only with weather conditions but also with the properties of ice in each region. Furthermore, the outcropping impurities from the ablating is likely to play a role to determine the surface reflectance and stripe patterns.