Abstract
Perennial snow patches are considered as indicators of permafrost occurence. There are no large glaciers on the territory of Bulgaria but small patches of snow and firn have been observed in the high mountains in the end of the summer. Perennial snow patches are considered as indicators of permafrost occurrence. In this paper we present results from geophysical investigations of Snezhnika microglacier situated in the Golyam Kazan cirque, Pirin Mountain, Bulgaria. Ground penetrating radar (GPR) and 2D Electro Resistivity Tomography (ERT) were used to estimate the thickness of the perennial snow patch as well as its subsurface structure. Measurements started in 2018 and continued over the next three years in order to evaluate changes in the snow patches' size and thickness. The mean thickness of Snezhnika is about 4–6 m, reaching up to 8 m in some areas. ERT measurements of the deeper parts of the microglacier beds show high electrical resistivities reaching over 60000 Ωm at a depth of 4–10 m. An anomaly at this depth is likewise distinguishable on the GPR profiles. These anomalies are interpreted as frozen zones and are consistently observed on the ERT and GPR profiles in the next two years of the study. These results imply for the first time the existence of permafrost in Pirin mountain and respectively in Bulgaria.
Highlights
Perennial snow patches are defined as snow fields existing for at least two consecutive summers (Watanabe, 1988). 82% of the 15 glaciers are smaller than 0.5 km2 and cover 21% of the Earth’s total glaciated area (Zemp, 2006)
There are no large glaciers on the territory of Bulgaria but small patches of snow and firn have been observed in the high mountains at the end of the summer
In this paper we present results from the first detailed geophysical investigations of Snezhnika microglacier, considered as the southernmost microglacier in Europe
Summary
Perennial snow patches are defined as snow fields existing for at least two consecutive summers (Watanabe, 1988). 82% of the 15 glaciers are smaller than 0.5 km and cover 21% of the Earth’s total glaciated area (Zemp, 2006). 82% of the 15 glaciers are smaller than 0.5 km and cover 21% of the Earth’s total glaciated area (Zemp, 2006) Despite their small size, perennial snow patches and microglaciers are an important object of study for their vital role as water reservoirs for many downstream ecosystems (Milner et al, 2009; Barry et al, 2011). Perennial snow patches and microglaciers are an important object of study for their vital role as water reservoirs for many downstream ecosystems (Milner et al, 2009; Barry et al, 2011) They are sensitive to climate change they are less influenced by global changes than glaciers. Perennial snow patches survive as a result of avalanching, wind-drift snow and shading (Grunewald et al, 2010) Together with microglaciers they are important for estimating permafrost areas in high 20 mountains as permafrost is the last stage of the glacial life cycle (Hughes, 2014, 2018).
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