北海道における地上風の特徴 : 主成分分析による解析
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概要
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In order to clarify the regionality of wind in Hokkaido objectively, the AMeDAS daily mean wind speed data are analized by means of principal component analysis (PCA). Each datum was converted into a deviation subtracted from the areal mean for each day. First three eigenvectors account for 24.9%, 16.3% and 10.5% of the total variance, respectively (i.e., cummulative for 51.7%) from the data of 1978, which describe more than half of the total variance of daily mean wind speed. The first positive eigenvector pattern (i.e., the total wind speed over the area with a positive sign is relatively greater than that of the area with a negative sign) shows the wind distribution pattern under the westerly general wind which is representative during winter monsoon. The second eigenvector pattern corresponds to 1) southwesterly or west-southwesterly general wind (positive pattern) and 2) northwesterly or southeasterly general wind (negative pattern). The third eigenvector pattern delineates the wind pattern under 1) northerly or northeasterly general wind (positive) and 2) southerly or southeasterly general wind (negative). Some air current maps are shown from the frequencies of wind directions with regard to the patterns under the stable synoptic situations. In the figures the clear air currents (stream lines) correspond to the region with strong wind supposed from the eigenvector patterns. The regionality of the wind is clarified by the use of cluster analysis with factor loadings which correspond to the correlation coefficients between the principal component and the wind speed of each point, and indicate the connection between those with time. The regionality of Hokkaido in relation to the variations of wind speed with time is mainly controlled by westerly general wind (i.e., whether the influence of it is strong or weak) in winter. Secondary feature is determined whether the topography surrounding the region is suitable as wind pass for southeasterly or southwesterly general wind.
- 北海道大学の論文
- 1983-08-15
著者
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