[A-CC25] Glaciology

[ACC25-P13] Normalized Vegetation Index of Mount Melbourne, Antarctica : Satellite Remote Sensing and GIS Analysis

*Tatsuya Kushida¹ (1.Graduate School of Environment and Information Sciences, Yokohama National University)

Keywords:remote sensing, vegetation, Antarctica

Mount Melbourne is an active volcano located in the East Antarctic of Antarctica. This area is inherently a harsh environment for living organisms, but due to the active volcano and rising temperatures, vegetation such as bryophytes and algae have been observed. Vegetated areas absorb heat better than ice sheets and contribute to ice sheet melting. a field survey of vegetation on Mt. Melbourne was conducted in 1987, and this survey confirmed the presence of red algae in addition to green mosses and algae. However, there have been no studies on the distribution of vegetation area and its relationship with surface temperatures in relation to annual and seasonal changes on Mount Melbourne. In this study, we compared the vegetation including red algae, snow cover area, and surface temperature during the period 2019-2021, and analyzed the conditions under which the vegetation grows. The objective of this study is to clarify the changes in vegetation area over a long period of time and to estimate the factors that contribute to these changes. Several satellite images were used to investigate vegetation, surface temperature, and snow cover area. For vegetation and snow cover area, Sentinel-2 satellite images were used, and for surface temperature, Landsat 8 and 9 satellite images were used. Satellite images of the study area were acquired mainly during the summer months of November through January, when vegetation was visible. For vegetation, NDVI was used to identify green vegetation, and red band/green band indices were used to identify red algae. These thresholds vary from study to study, but in general, lower thresholds were set for areas with less vegetation, so lower thresholds were also set for this study. Arc GIS Pro software was used to analyze the acquired satellite images. Comparisons were made over a wide area with three years of data (approximately 10 days of data for the summer season) and locally with a 100m grid (only for the summer season of 2021-2022) for one year of seasonal changes. In addition, the data were overlaid with elevation data to explore trends in vegetation and surface temperatures. First, for the broad-scale comparison, we compared the total vegetation area and the average ground surface temperature for the entire target area. The vegetation area tended to be higher from December to early January, and the ground surface temperature tended to be higher in mid-December. In comparison with the snow covered area, the vegetation area decreased as the snow covered area increased. The results of scatter plots of vegetation area and surface temperature for each 100-m grid showed that the approximate straight lines were positive and the correlation coefficients were 0.2 to 0.5, indicating that there was a correlation, albeit weak. Using the elevation data, we observed vegetation distribution and surface temperature on a 3D map, and found that vegetation thrived on the northern slope, and points with high surface temperatures were often located on the same slope. Vegetation on Mt. Melbourne was most abundant during the summer months from December to early January, and its distribution was concentrated on the northern slope. In the 100-m grid, all correlations between vegetation area and surface temperature were positive. This led to the conclusion that vegetation was more present in areas with higher ground surface temperatures.