Adaptive polarimetric decomposition using incoherent ground scattering models without reflection symmetry assumption

Most of the current incoherent polarimetric decompositions employ coherent models to describe ground scattering;however,this cannot truly reflect the fact especially in natural ground surfaces.This paper proposes a highly adaptive decomposition with incoherent ground scattering models(ADIGSM).In ADIGSM,Neumann’s adaptive model is employed to describe volume scattering,and to explain cross-polarized power in remainder matrix,so that we can obtain orientation angle randomness for both volume scattering and the dominant ground scattering.The computation of volume scattering parameters is strictly constrained for non-negative eigenvalues,while the volume scattering parameters that explain the most cross-polarized power are selected.When applying ADIGSM to NASA’s UAVSAR data,the negative component powers were obtained in quite a few forest pixels.Compared with several newest decompositions,the volume scattering power is obviously lowered,especially in areas dominated by surface scattering or double bounce scattering.The orientation angle randomness of each component is reasonable as well.ADIGSM has potential to be applied in the fields such as PolSAR image classification,land cover mapping,speckle filtering,soil moisture and roughness estimation,etc.

The consistency between Na content distribution at the subsurface and the lake body’s movement in Lop Nur

Historically,Lop Nur was a large and famous salt lake that acted as an important geographic position along the ancient‘Silk Road’,and was associated with the surrounding old civilizations,such as Loulan and Haitou.However,it dried up before 1972.It shows a clear‘Ear’feature on synthetic aperture radar(SAR)images.The objective of this paper is to interpret Lop Nur’s environmental evolution during its drying-up process based on an analysis of its sodium sedimentary feature.The genetic algorithm-partial least squares approach is introduced as a modeling method to retrieve the subsurface sodium content from polarimetric parameters obtained by Cloude decomposition.As a result,the R2 and root-mean-square error can reach 0.7 and 9.1 g/kg.It is suggested that the subsurface salt content was the primary reason for the bright-grey strips textures on SAR images.Furthermore,our results show that the sodium content along the same strip changed,with its distribution exhibiting consistency with the lake body’s movement driven by the strong wind.In future,high-precision topographical data will be considered,and should be helpful in the analysis of lake body movement.The method of this paper can also be applied in other similar dried salt lakes.