Revision of climatic division for Japanese snowy areas based on the new climatic data mesh climatic data of Japan and studies on climatic responses of Japanese snowy areas to recent climatic change

利用新开发的网格气候数据，我们可以根据日本所有雪区的隆冬积雪特征完成气候区划，并绘制新的气候区划数字地图。在这次修订中，我们可以完善我们气候区划的范畴之一——深区的定义和条件，以便根据观测资料更准确地阐明其气候含义。新定义表明了在气候期（30年）中，深灰发展到显著水平的冬季的次数比率，可区分为深灰区。我们还利用官方气象观测站的数据，研究了最大母猪深度、平均气温和积雪地区降水的月气候值之间的关系。结果表明，这些定量关系与我们的气候区划密切相关。例如，湿雪区站点气候资料中发现的月最大雪深上限在其他较冷气候区不成立。此外，通过比较1961 - 1990年的正常值与1971 - 2000年的正常值，我们可以明确日本雪区对最近暖冬的响应。湿雪区强降雪区最大雪深变化剧烈。结果表明，这些较温暖的强降雪地区对气候变化非常敏感，气候响应也与本研究引入的气候区划有关。

We could complete the climatic division based on their snow-cover characters in mid-winter of all snowy areas over Japan and draw up a new digital cartographic map for the climatic division, using the newly developed mesh climatic data Mesh climatic data of Japan. In this revision we could improve the definition and conditions for depth-hoar region, one of the categories for our climatic division, to clarify the climatic implication more precisely according to observed data. New definition indicates the rates of numbers of winter seasons in which depth hoar developed to significant level that was distinguishable as the depth-hoar region, during climatic period (30 years).We also investigated relationships in monthly climatic values among maximum sow depth, mean air temperature, and precipitation of snowy areas using data set obtained by the official meteorological observation sites. The results reveal that these quantitative relationships closely relate to our climatic division. For example, the upper limit of monthly maximum snow depth found in the climatic data of the sites in wet-snow region could not hold in other colder climate regions.Moreover we could clarify responses of Japanese snowy areas to the recent warmer winters, comparing normals (climatic values) from 1961 to 1990 with that from 1971 to 2000. Drastic changes were found in the maximum snow depth of heavy snowfall areas in the wet-snow region. It shows that such warmer heavy snowfall areas are very sensitive to climatic changes and that climatic responses also relate to the climatic division introduced in this study.