National Repository of Grey Literature 2 records found  Search took 0.00 seconds. 
Supraglacial lakes detection and volume estimation from remote sensing data
Rusnák, Samo ; Brodský, Lukáš (advisor) ; Šobr, Miroslav (referee)
Supraglacial lakes detection and volume estimation from remote sensing data Abstract Supraglacial lakes play an important role in understanding glacier dynamics, including their response to climate change. This thesis explores the problematics of estimating lake depth and volume using a physical model. This brings challenges in considering the influence of various factors, such as cryoconite on glacier surface and suspended particular matter, which influences physical model, which is in research mostly neglected. Regression analysis of the g parameter of a physical model, representing light attenuation coefficient, and supervised classification of supraglacial lakes is applied in this thesis. The results reveal the variability of parameter Ad, representing lake bottom albedo reflectance, and its impact on predicted supraglacial lakes depth and volume. The results highlight the problem of global parameterisation of the physical model of supraglacial lakes and the need for further research to improve its accuracy and explore future possibilities in this field. Keywords: supraglacial lake, remote sensing, machine learning, physical model, depth estimation, regression analysis
Remote Sensing of Surface Meltwater on the Glaciers of Svalbard
Sieglová, Eliška ; Margold, Martin (advisor) ; Engel, Zbyněk (referee)
Supraglacial lakes pond meltwater on the surface of glaciers. They form in the ablation zone during the ablation season and their darker surface lowers the albedo of the glacier. Once drained to the glacier bed, they may affect basal sliding and flow velocities of the glacier. High- resolution imagery from the Sentinel-2 mission was used to characterize the ablation season on two glacier regions of Svalbard: Hinlopenbreen glacier on the east coast and Kongsbreen and Kronebreen glaciers on the west coast of Spitsbergen. The first supraglacial lakes appeared in the first half of June in the west region and in the second half of June in the east region. The peak of the lake area was observed around the turn of June and July in the west region and around the half of July in the east region. The time of the first appearance of supraglacial lakes corresponded with temperatures reaching positive values. They first formed in lower elevations and started progressing higher with rising temperatures. Most supraglacial lakes formed between 600 and 700 m a.s.l. in the west region and between 400 and 500 m a.s.l. in the east region. In the east region a significant number of the supraglacial lakes (12 % of their total area) formed above the estimated equilibrium line altitude of 600 m a.s.l. Further research...

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