We present a physical model that accounts for the curl mechanism of a curling stone on ice pebbles. The evaporation-abrasion model is based on the two essential features of curling: pebbles and running band. The ice friction coefficient at the rear half of a running band is larger than that at the front half because of cooling due to evaporation of pebbles. The asymmetry of the friction force is enhanced by mechanical interactions of ice debris produced by the front running band with the rear band, and result in the curl, or lateral deflection of the stone.The asymmetry is larger, that is the curl distance is larger, at smaller velocity, higher temperature, lower humidity, and larger radius of a running band. However, it is independent of the angular velocity, that is the curl distance does not depend on the total number of rotations.
An observational study was conducted for the first time at the ablation area of Potanin glacier, Tavan Bogd region, in western Mongolia in 2007-2008 in order to understand the meteorological and glaciological features. In the study, annual meteorological data and summer surface ablation data were obtained. It was found that the annual mean temperature was -8.8°C on the glacier, and the surface albedo exhibited altitude dependence. Further, the precipitation measured near the glacier during summer was much larger than that measured at Ulgii. Surface energy balance was calculated by a gradient method; it revealed that shortwave radiation was the dominant heat source of surface ablation, whereas the contribution rate of turbulent heat flux was small. The ablation calculated by an equation constructed using the measured radiation showed fairly good correlations with the observed daily ablation, whereas the degree-day method showed good correlations for cumulative ablation. This study revealed the certain uniqueness of the glacio-climate in this region, and showed the further necessity of analysis on the relation of meteorological conditions and the mass balance of the glacier.
Spatial variability of the chemical constituents of winter precipitation on the eastern-western slopes of Mt. Norikura (alt. 3025m) of Japan Northern Alps was examined to clarify the transport process of aerosol that flows over the mountain barrier. The concentrations of chemical constituents in the snow recorded at the upper part of the mountain (above alt. 2420m) make a little difference. However, at the lower part of the mountain (below alt. 2420m), Cl- concentration in the snow on the eastern slope was lower than that on the western slope; non-sea-salt SO42- (nssSO42-), NO3-, nssCa2+, nssMg2+ and NH4+ concentrations on the eastern slope was higher than that on the western slope. The prevailing westerlies raged at the western and alpine parts of the mountain. On the eastern part of the mountain, the easterlies were predominant. We infer that the snow below an altitude of 2420m, in comparison to the other parts of mountain, is under relatively greater influence of the local emission of the chemical constituents.
Glaciar Perito Moreno is one of the major freshwater calving glaciers in the Southern Patagonia Icefield. Its fast-flowing characteristic is probably due to high water pressure at the glacier bed, however, subglacial conditions have never been observed in Patagonia until our recent undertaking. To investigate the role of subglacial water pressure in the calving glacier dynamics, we performed hot-water drilling at Glaciar Perito Moreno from February to March 2010. This study represents the first attempt ever at hot-water glacier drilling in Patagonia. Two boreholes were drilled to the bed at 4.7km upglacier from the terminus, where the ice was revealed to be 515±5m thick and the bed located at about 330m below the proglacial lake level. The water levels in the boreholes were >100m above the lake level, which indicates that more than 90% of the ice overburden pressure was balanced out by the subglacial water pressure. Water in the boreholes had drained away before the drilling reached the bed, suggesting the existence of an englacial drainage system. These results provide crucial information for understanding the hydraulic and hydrological conditions of calving glaciers. In order to drill a 500m deep glacier, an existing hot-water drilling system was adapted by increasing the number of high-pressure hot-water machines. The drilling operation at Glaciar Perito Moreno confirmed the system's capacity to drill a 500-m-deep borehole at a rate of 50mh-1 with fuel consumption rates of 15.7lh-1 for diesel and 3.9lh-1 for petrol.