The occurrence of red tides hit an accumulative area of 13,738 square kilometers, up by 18.3 percent.

全年累计发生赤潮面积13738平方公里，增加18.3%。

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Then utilizing principal component analysis, the author analyzed the data of each period and concluded that the first and second principal component's accumulative proportion is more than 85 percent.

根据第一主成分和第二主成分的特征向量计算各时间段的第一主成分和第二主成分的指标值。

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