The remote sensing composite information entropyand types of Nansha coral reef atolls

In the viewpoint that the coral reef atolls' growth index of the Nansha Islands is influenced by many factons,the measured remote sensing composite information including some mutually related factors is divided into 10 geographic events as N₁,N₂…,N₁₀,and the analysis of the atolls' infomation entropy is made.From the value of the entropy,the closed related factors with the index of the emerged atolls are shown.In proper order,the factors are reef top's area(0.319),lagoon's area(0.324),open-degree of atoll(0.336),trend of atoll(0.551).On the basis of this work,a new description function of the emerged atoll growth index is proposed.This function can be used to identify the open type of Nansha atoll growth.