Analysis of NDVI variation and snowmelt around Zackenberg station, Greenland with comparison of ground data and remote sensing

英语. Snow and permafrost are significant climatic factors affecting the climate in high latitudes and especially in arctic regions. Moreover, results of conducted scientific studies have shown that snow is crucial for photosynthetic activity and therefore vegetation vigor and growing season in arctic environments. This master thesis aims to investigate the changes in photosynthetic activity in Zackenberg, located in the eastern coast of Greenland with estimation of the fluctuation of the normalized vegetation index (NDVI) from satellite images and the changes in snowmelt and active layer thickness with the study of ground data obtained by scientific measurements conducted in the established research station of Zackenberg. Moreover, this study tries to relate the variations in photosynthetic activity expressed by the vegetation index with snow depth and length of snow season, as well as with properties of permafrost, like the thickness of the active layer. The time period for which this study is conducted includes the last 10 years, between 2005 and 2014. Analysis is performed with the help of statistics and by using principles of regression analysis. Results show fluctuations in photosynthetic activity as well as in the duration of the growing season. Furthermore, correlations between snow depth and time of snowmelt (expressed by snow cover percentage) and photosynthetic activity are detected from the regression analysis, showing that snow depth and time of snowmelt affect the seasonal vegetation activity and enhancing the argument on the importance of snow for the high northern latitudes. On the other hand, results from the regression analysis show that photosynthetic activity is not affecting the active layer thickness.

英语. Greenland is the world’s largest island, located in the northern part of the earth΄s surface. The biggest part of the island is covered by snow and glaciers throughout the whole year. However, there are areas that some vegetation can be present during a small period of around three months in the summer, when the snow is melted. Snow is one of the main characteristic in the climate of Greenland. A research station is located in Zackenberg, eastern Greenland, where measurements of various characteristics that can affect the climate, the hydrology and the flora and fauna are taken. This study aims to show the changes in vegetation in the study area of Zackenberg with the use of satellite images and the help of a special index that estimates the differences in photosynthetic activity. Moreover, how changes in the characteristics of snowfall can affect the vegetation is also evaluated with the help of statistical analysis. Parameters that were studied are snow depth, snow cover percentage in the study area as well as active layer depth, the upper part of soil above the permanent layer of frost in arctic areas that thaws in the summer and freezes again in winter. Results show fluctuations in the photosynthetic activity as well as the duration of the growing period during the last ten years (2005-2014). Moreover, statistical analysis showed that snow depth and time of snow melt (expressed by total snow cover percentage in the area) affect the photosynthetic activity and therefore the strength of vegetation. On the other hand, statistical analysis showed that photosynthetic activity and vegetation is not affecting the thickness of the active layer.