Uniaxial compression experiments on horizontal and vertical samples of first-year freshwater ice in a res- ervoir were conducted at different temperatures and strain rates with an electronic universal machine equipped with low temperature cabinet. The results show that there is no difference between the strengths of two horizontal samples with grain sizes ranging from 1 to 4,mm and 4 to 14,mm, while the strength of the 1-4 mm vertical samples is 1.4 times higher than that of the 4-14 mm vertical samples because of the change of crystal structure. For different loading directions, the strengths of the horizontal samples do not differ from those of the vertical samples with the same grain sizes. The relation among the uniaxial compressive strength, strain rate and temperature was established through data analysis in both the ductile and brittle regions.
Accelerated decline of summer and winter Arctic sea ice has been demonstrated progressively. Melt ponds play a key role in enhancing the feedback of solar radiation in the ice/ocean-atmosphere system, and have thus been a focus of researchers and modelers. A new melt pond investigation system was designed to determine morphologic and hydrologic features, and their evolution. This system consists of three major parts:Temperature-salinity measuring, surface morphology monitoring, and water depth monitoring units. The setup was deployed during the ice camp period of the fourth Chinese National Arctic Research Expedition in summer 2010. The evolution of a typical Arctic melt pond was documented in terms of pond depth, shape and surface condition. These datasets are presented to scientifically reveal how involved parameters change, contributing to better understanding of the evolution mechanism of the melt pond. The main advantage of this system is its suitability for autonomous and long-term observation, over and within a melt pond. Further, the setup is portable and robust. It can be easily and quickly installed, which is most valuable for deployment under harsh conditions.
