Development of a new shallow ice core drill.

Records of sea-ice extent and air temperature at the Sea of Okhotsk from an ice core of Mount Ichinsky, Kamchatka

“…It took a total of 42.5 hours to drill down to 115 m. An ice core 90–93mm in diameter and ~0.5m long was consistently recovered from each drilling run. No brittle ice was found in the entire depth, despite the fact that brittle ice usually appears below depths of 100–150m in mountain glaciers or small ice caps (Takahashi, 1996; Koci, 2002).…”

Ice-core drilling problems and solutions

“…Consequently, several special shoes have been designed for drilling in warm ice. One of the warm-ice shoe designs (the 'dolphin' type) featuring a small contact area was proposed by JARE specialists (Takahashi, 1996). Unfortunately, these shoes did not produce the hoped-for improvement in drilling in the warm ice.…”

Alpine ice-core drilling in the North Pacific region

“…The system was also used during an expedition to Belukha mountain in the Altai mountains, central Asia, in 2003 (Tsushima and others, 2014). The drill was an improved version of a previous model used at Ushkovsky for high-elevation work (Takahashi, 1996). The barrel length was 1.35 m, shorter than the previous version (2.00 m), which reduced the operating space and made handling easier.…”

“…The packed water bearing the ice chips prevented the cutters from biting into the ice. To avoid this, we used a new drill cutter mount called a ‘dolphin mount’, which was designed for ‘warm’ glacier drilling (Takahashi, 2005) (Fig. 5).…”

“…This brittle-ice problem is well known and often appears below depths of 100–150m in alpine glaciers or small ice caps (e.g. Takahashi, 1996; Koci, 2002). Below 100m depth, the air pressure in bubbles in ice cores increases, leading to ice-core brittleness.…”