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Ice cave Ledena jama in Lomska duliba (Velebit Mt., Croatia) – the promising site for ice cave monitoring

Ledena jama (Ice shaft) is located in the SW part of Lomska duliba valley on Velebit Mt. It is a knee-formed vertical cave (shaft) consists of 536 m deep vertical passages and chambers interconnected with shorter narrower horizontal passages. The 50 m wide and 60 m long funnel-like entrance is located at the Lomska duliba valley bottom at elevation of 1235 m. Wide open entrance enables accumulation of snow and strong microclimate influence from the surface so entrance chamber acts as a cold trap. Despite of openness, due to the steep slopes of the entrance vertical passage it is shady and even during the summer most of the day protected from the direct sunlight. At the depth of 50 m there is a chamber bottom consist of snow, névé, firn and ice providing additional cooling effect. The snow is allochthones deposit that accumulates from outside the cave: directly from the precipitation and indirectly by sliding and collapsing from the steep slopes and some trees around the entrance. The névé, firn and ice are autogenic deposits forming from deposited snow and by freezing of percolating water. This infilling reaches the depth of 90 m and separates the entrance part from the rest of the vertical passages and chambers. The main factors affecting the accumulation of snow and ice are location (elevation), abundant precipitation with a lot of snow, and low air temperatures due to frequent temperature inversions in Lomska Duliba. Ledena jama in Lomska duliba is very promising site for research of ice cave microclimate and dynamics of ice-snow deposits so microclimate research started in 2012. The levels of snow and ice are also in the process of monitoring and variations were recorded. Its advantage for research is in easy access, large dimensions, and abundance of various deposits connected with different geomorphological processes. Air temperature variations (compared to surface values) indicate dynamic system that requires continuous data collection, observation and analyses. The plan for future research is to establish permanent meteorological station for measuring T, RH, air circulation and other various parameters in the area of Lomska duliba and in Ledena jama. There are also opportunities for ice, water and organic matter sampling and dating.

Ledena jama; ice cave; monitoring

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