Adam CHOIŃSKI¹, Mariusz PTAK¹ & Agnieszka STRZELCZAK^2*
1Institute of Physical Geography and Environmental Planning, Adam Mickiewicz University, Dzięgielowa 27, 61-680 Poznań, Poland; e-mail: marp114@wp.pl, choinski@amu.edu.pl,
²Faculty of Food Sciences and Fisheries, West Pomeranian University of Technology in Szczecin, Pawła VI 3, 71-459 Szczecin, Poland; *e-mail: Agnieszka-Strzelczak@zut.edu.pl

AREAL VARIATION IN ICE COVER THICKNESS ON LAKE MORSKIE OKO (TATRA MOUNTAINS)

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This study presents the changes in ice cover thickness on the surface of a mountain lake Morskie Oko (33.5 ha, 1392.8 m a.s.l.) located in the Tatra National Park in the Tatra Mountains (the highest mountain range of the Carpathians). The course of ice phenomena is similar to those observed on lakes in other parts of the world: over the last forty years the duration of ice phenomena decreased (by 9 days·decade^-1), similarly to the duration of compact ice cover (9.5 days·decade-1) and the maximum icecover thickness (2.2 cm·decade-1). Another issue is the variation in the areal ice cover thickness – stilllittle discussed comparing to long-term studies of ice phenomena. The thickness of ice on Morskie Okowas measured during eight field investigations carried out over years 2006-2012 and jointly 160boreholes were made in different part of that water body. Results obtained from those field works showeda great areal variation in a given year as well as between consecutive years. Differences in ice coverthickness sometimes were slight and amounted to 3cm (24.03.2010) while in other cases turned out to beconsiderable (31 cm on 9.05.2006). The local conditions, for example topography (which influenced theshadowing of part of the lake, i.e. resulted in the isolation from sunlight) were the main factors thatdifferentiated the aerial distribution of ice cover. The unshaded areas are subjected to faster ice meltingwhich strongly influences the thickness of ice cover. Another phenomenon observed on 20.02.2012 wasstrictly connected with the under-ice circulation of water which washed away the ice.