灾害的年内分布规律研究

灾害的年内分布是有一定的规律可循的。月分布百分数、集中期、集中度、频发期、频发值和频发度是描述灾害年内分布的特征值。本文提出的频发期和频发值揭示了灾害年内分布的一般规律，可以为灾害预报提供一定的理论依据。

A STUDY ON THE ANNUAL DISTRIBUTION OF DISASTERS

or calculating the yearly distribution of disasters the Monthly Distribution Percentage Method and the Vector Composition Method are generally used. In this paper, the circumference orientation is designated to the date of disasters and the radiuS distance to their strength. By calculating the density value within the annulus and drawing the isodenses, the density isogram of disasters can be completed. me center of the isgram indicates the date that disasters occur most frequently (the frequently occurring date) and their strength (the frequently occurring value).The possibility of disasters occurrance is called the frequently occurring degree.The distribution rules of disasters in a year are as follows: 1) Disasters of single-peak type distribution appear in some specific durations of the year. 2) The peak type of yearly distribution of the same disaster is different in different zone. 3) Concentration degrees of disasters of different year groups and peak types are different. 4) The more the yearly distribution of disasters concentrates, the bigger the frequently occurring degree of disasters is. 5) If the yearly distribution of disasters is different, the change of density center of disasters is different. 6) The especially his values of strngth of disasters often appear near the position indicated by density cent6r. 7) Strength of disasters usually comes close to or is smaller than me frequently occurring value in the locality far away from density center. 8) Disasters often occur in the days of solar terms or their neighbourhood.