盐渍化土壤水分微波雷达反演与验证  

Inversion and verification of salinity soil moisture using microwave radar

作　　者：王学[1] 刘全明[1] 屈忠义[1] 王丽萍[1] 李相君[1] 王耀强[1] 

机构地区：[1]内蒙古农业大学水利与土木建筑工程学院,呼和浩特010018

出　　处：《农业工程学报》2017年第11期108-114,共7页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金项目(51249007;51569018;51169016);内蒙古自然科学基金项目(2013MS0609);"十三五"国家重点研发计划项目(216YFC0501301)

摘　　要：土壤介电常数是微波遥感进行土壤含水率测量的物理基础,尤其介电常数实部是必须解决的问题,土壤介电特性的研究显得尤为重要。该文目的是试验与评价C波段RADARSAT-2 SAR(synthetic aperture radar)数据模拟土壤介电特性,进而反演土壤水分的性能。以受盐渍化影响较严重的内蒙古河套灌区解放闸灌域为试验区,首先回归分析了介电常数实部与SAR四极化后向散射系数、地表粗糙度的复杂关系,并与Oh经验模型对照,其决定系数R2为0.859 7,模拟精度较高;然后验证常用的2个介电常数模型,Dobson半经验模型、Hallikainen简化实部经验模型模拟的介电常数实部与实测值的决定系数R^2分别为0.935 9、0.869,表明2个模型均能模拟地表土壤水分与介电常数实部的密切关系;最后构建了Dobson模型、Hallikainen简化实部模型反演土壤含水率的模型,并与统计回归模型比照,其模拟数值与土壤实测值的决定系数R2分别为0.803 8、0.737 4、0.842 1,均方根误差RMSE分别为5.2%、5.7%、5%。Dobson模型与统计回归模型反演结果与实地土壤墒情分布较为吻合,具有良好的精度和适用性,从而建立了一个较为完整的土壤介电特性研究体系,为微波遥感监测土壤水分奠定了基础。Soil dielectric constant is the physical basis for soil moisture simulation based on microwave remote sensing,and especially the real part of the dielectric constant is of great significance to the research of the soil dielectric characteristics.Main aim of this study was to investigate capability of C-band RADARSAT-2 SAR（synthetic aperture radar） data applied in the soil dielectric characteristics monitoring and the soil moisture inversion over agricultural fields.Bare area of Jiefangzha sub-district of Hetao Irrigation District in Inner Mongolia of China was selected as the study region,which was influenced by soil salinization seriously.In order to achieve above purposes,an image of Radarsat-2 SAR was bought in April 2016,which has a kind of four fine polarization SLC（single look complex） format,covering an area of 25 km×25 km with 8 meter ground resolution.Taking spatial uneven distribution of the saline soil into account,100 sampling points were designed in the study area,and soil digging depth was 10 cm.Hand-held GPS（global positioning system） receiver was used to record coordinates of the sampling points.The experiment data included the soil dielectric real constant,surface roughness,surface temperature,percentages of clay and sand particles,soil bulk density and soil moisture.Agilent microwave network analyzer was used to measure the real part value of soil dielectric constant with coaxial probe method.Surface roughness was measured using centimeter grid profile plate to calculate the value of RMS（root mean square） height and the correlation length,and then composite roughness was got to represent the surface roughness in later research.Real-time ground temperature of the sampling points was measured by geothermometer.Particle analysis was fulfilled with laser particle size analyzer named Helos/B,obtaining the percentage content of clay and sand particles.Soil bulk density was measured by ring cutter.Soil moisture was measured by way of drying.SAR scape module of ENVI software was mainly

关 键 词：土壤水分 遥感 模型 土壤介电特性 Oh模型 Dobson模型 Hallikainen简化实部模型 盐渍化 

分 类 号：S152.7[农业科学—土壤学]