异质性地表土壤冻融循环监测网络的优化采样设计——以黑河祁连山山前地区为例

Spatial Sampling Design of the Sensor Network for Monitoring the Surface Freeze/thaw Cycles over the Heterogeneous Surface in the Heihe River Basin

在黑河祁连山山前地区建立分布式的土壤温度/水分传感器监测网络,准确获取异质性地表的遥感像元真值,用于地表冻融状态分类及土壤水分定量反演算法的发展完善和真实性检验,以及两者的降尺度研究均具有重要意义。传感器监测网络节点的空间布局直接影响观测有效性及其数据质量,一种基于异质性地表的均值估计方法被用于空间节点的优化采样设计:即以地表温度为目标变量,将研究区划分为相对均质的若干层(子区域),计算各层及总体的变异函数参数作为代价函数的输入,通过最小化目标变量的估计方差,实现传感器网络节点在各层的空间分布,准确地捕捉区域内部的异质性。结果表明,分层后各层的异质性相对于总体都有所下降,优化的节点空间布局具有较好的属性代表性,对于异质性较强的局部区域,有较高的样本密度。

A method,means of stratified non-homogeneous surface,is used to design the sensor network in the middle reach of Heihe river basin to capture the surface freeze/thaw cycles.This method decomposes a heterogeneous surface into several subareas which are homogeneous.Its estimation variance is calculated by the kriging technique and stratified sampling.With the goal of minimizing the estimation variance,nodes of the sensor network are optimally distributed in the study area by the simulated annealing algorithm.The result shows that optimal samples have good representativeness,and high density of samples are assigned to the stronger heterogeneous regions.