基于主/被动微波观测试验的土壤水盐含量协同反演

Soil salinization is one of the main types of soil degradation, which has become a crucial scientific issue associated with social economy, ecological environment and sustainable development of modern agriculture. Microwave remote sensing has the unique advantage in monitoring the variation of soil moisture and salinity due to its high sensitivity to soil dielectric constant. However, due to the lack of the understandings in the dielectric characteristic, scattering and emission mechanism of saline soil, there is little mature and robust microwave remote sensing retrieval algorithm for soil moisture and salinity estimations. This proposal is to develop an approach for a joint retrieval of soil moisture and salinity based on ground-based microwave radiometer and scatterometer measurements. The main research subjects are: 1) conducting a ground-based microwave experiment to observe simultaneously soil brightness temperature, backscattering coefficient, permittivity and corresponding surface soil parameters (including soil moisture, salinity, roughness etc.). 2) developping a dielectric constant model for saline soil under the basis of traditional non-saline soil dielectric constant model. 3) Simultaneously estimating soil moisture and salinity through minimizing the value of a cost function: constructed respectively by active microwave observations and AIEM simulations; passive microwave observations and L-MEB simulations. 4) The proposed methods will be applied in the typical oasis farmland and desert surfaces of the middle reaches of Heihe River Basin.

土壤盐渍化是土地退化的主要类型之一，已成为关系到社会经济、生态环境及现代农业可持续发展的重大科学问题。微波遥感对土壤介电常数变化的高度敏感性，使其在土壤水盐含量监测方面有着独特的优势。然而，由于对盐渍土的介电特性及微波散射/辐射机理认识不足，目前尚未形成成熟、稳健的微波遥感反演方法。本项目拟采用地基微波散射计和微波辐射计开展盐渍土地表散射及辐射特性的控制试验，同步测量微波亮温、后向散射系数、介电常数及相应的地表参数（土壤水分、盐分、粗糙度等），在传统的非盐渍土介电模型基础上发展适用于多波段微波的盐渍土混合介电模型，并借鉴土壤水分反演方法，分别基于主被动微波观测数据与AIEM和L-MEB模型的正向模拟，采用代价函数法同步估计土壤介电常数及粗糙度等参数，进而同步反演土壤水分和盐分，并将该方法应用于黑河中游典型农田和荒漠化盐渍土区域。

土壤盐渍化是土地退化的主要类型之一，已成为关系到社会经济、生态环境及现代农业可持续发展的重大科学问题。微波遥感对土壤介电常数变化的高度敏感性，使其在土壤水盐含量监测方面有着独特的优势。然而，由于对盐渍土的介电特性及微波散射/辐射机理认识不足，目前尚未形成成熟、稳健的微波遥感反演方法。本项目拟采用地基微波散射计和微波辐射计开展盐渍土地表散射及辐射特性的控制试验，同步测量微波亮温、后向散射系数、介电常数及相应的地表参数（土壤水分、盐分、粗糙度等），在传统的非盐渍土介电模型基础上发展适用于多波段微波的盐渍土混合介电模型，并借鉴土壤水分反演方法，分别基于主被动微波观测数据与AIEM和L-MEB模型的正向模拟，采用代价函数法同步估计土壤介电常数及粗糙度等参数，进而同步反演土壤水分和盐分，并将该方法应用于黑河中游典型农田和荒漠化盐渍土区域。