Some properties of granular ice and evaluation of its effect on atmospheric and oceanic environments.

北冰洋的海冰主要是柱状结构。然而，近年来在南极洋和鄂霍次克海等季节性冰带的研究发现，该地区以颗粒状结构的冰为主。对海冰增长的贡献已成为主要的兴趣。预计冰结构的不同会导致生长过程、辐射和渗透性等物理性质的不同。我们试图从实验和野外观测两方面阐明上述两种不同类型冰的物理性质差异。实验研究是在国家地球科学与防灾研究所长冈冰雪研究所新镇分院装备精良的低温实验室冰冻圈环境模拟器进行的。我们在两个搅拌/未搅拌的水箱中种植海冰。雪冰是一种颗粒状冰，是由人工造雪机在两个储罐中积累的雪长成的。在实验过程中，我们偶尔观察到海冰增长的特征。我们也进行了辐射测量，即反照率和衰减系数。实验结束后，我们观察了冰的结构，并测量了密度、盐度和同位素组成。实地观测是在从河口到萨罗马湖东部开口的一条线上进行的。观测的目的是研究海冰结构随母水盐度的变化以及雪冰和结构冰类型的贡献。我们还测量了不同冰结构的渗透率差异。

Sea ice in the Arctic Ocean has predominantly columnar structure. However, from recent studies conducted in the seasonal ice zone, e.g. Antarctic Oceans and the Okhotsk Sea, it is found that ice with granular structure was dominant at the zone. The contribution to sea ice growth has become of major interest. It is expected that the difference of the ice structure would cause difference of physical properties, e.g. growth processes, radiation and permeability. We tried to clarify the difference of the physical properties between the above two difference of the ice types both experimental and field observations.Experimental study was conducted in the Cryospheric Environment Simulator, a highly equipped cold laboratory, at Shinjo Branch, Nagaoka Institute of Snow and Ice Studies, National Research Institute for Earth Science and Disaster Prevention. We grew sea ice with the ice types in two stirred/unstirred water tanks. Snow ice, a kind of granular ice, was grown from snow accumulated by an artificial snow machine in the two tanks. Occasionally we observed the features of sea ice growth during the experiment. We also conducted radiation measurements, i.e. albedo and attenuation coefficient. After the experiments, we observed the ice structure and measured density, salinity and isotopic compositions.Field observation was carried out on a line from the mouth of a river to the opening in the eastern part of Lake Saroma. The aim of the observation is to investigate change of sea ice structure with the parent water salinity and contribution of both snow and structural ice types. We also measured permeability difference with ice structure.