多変量解析法による熱的要素の分析から見た北海道の気候環境の地域特性

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In order to clarify the environmental regionality in Hokkaido, some thermal climatic elements at about 140 sites are analysed with time variation (day-to-day variation) in relation to synoptic meteorological phenomena. Both principal component analysis and cluster analysis using factor loadings are applied. The four regions with different time variation types of sunshine duration are distinguished. Especially, the southeastern side of Hokkaido has fairly specific regionalities in comparison with the other regions. The boundaries between the regions are comparatively clear. As for the temporal variation of air temperature, the difference of the regional characteristics between the inland and the coastal areas is the primary feature. The distribution patterns of maximum air temperature are governed by the patterns of sunshine duration, wind speed and the influence of the sea. The coastal zone is divided into four subregions by the variation types of the maximum air temperature with the intensity of sea effect. The boundaries along the mountains are clearly marked in the maximum air temperature patterns controlled by the sunshine duration. On the other hand, the boundaries in the minimum air temperature patterns become obscure in general since the regional characteristics of minimum air temperature are controlled mainly by the wind distribution pattern. However, some boundaries such as Kitami Mountains exist although they show the features of transitional zone. The patterns of daily mean air temperature are always concerned with one or more patterns of maximum and minimum air temperatures and show the mean features of such patterns. These results often show that a pattern of sunshine duration and a corresponding pattern of air temperature prevail at the same time, e. g., under an Ogasawara anticyclone. But, in general, including these cases, each climatic element does not have a distribution pattern resembling the other with regard to synoptic scale phenomenon. It is because that the patterns of air temperature are influenced not only by sunshine duration but also by wind and sea surface temperature. To clarify the thermal climatic regionalities caused by plural climatic elements, the clustering method is used again for two climatic elements, i. e. sunshine duration and daily mean air temperature. As a result, four inland regions and four coastal regions are distinguished at the third order of the clustering step. Especially the boundaries running parallel to the shoreline are notable in this study. Hidaka Mountains and Akan-Shiretoko Mountains are important boundaries from a viewpoint of variation of thermal climatic elements. In contrast, Oshima Peninsula is preferably separated from the main part (northeastern part) of Hokkaido by the line of Hidaka-Yubari-Mashike Mountains. It is stressed that this study adds the following new knowledge to the climatic regionalities of Hokkaido at lower ordered division ; -namely, Kitami Basin and the inland part of Ishikari-Sorachi Lowlands are distinguished from the other regions. Furthermore, it is also revealed first that the characters of regional climate around Shiribeshi Mountains are the same as those of the inland parts of Ishikari-Sorachi Lowland.
北海道大学の論文
1984-03-30

多変量解析法による熱的要素の分析から見た北海道の気候環境の地域特性

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