Yu Liu

institute of remote sensing and digital earth,Cas ,china · remote sensing

We apply Shannon entropy, an information content measure, in sensitivity analysis (SA), stemming from the fact that the essence of SA is to preserve the maximum information content of the parameters of interest that are inverted from the radar response. Then, the sensitivity to the observation configuration and surface parameters is subsequently an...

This paper presents a new expression for multiple scattering by including the upward and downward propagation waves in the medium 1 and medium 2. Unlike the single scattering, the multiple scattering accounts for the interactions, up to second order, among all the spectral components of surface roughness spectrum. Though the derivation is mathemati...

We analyzed the bistatic coherent scattering mechanism of a layered randomly corrugated snow surface, a typical rough surface, with radar polarimetry theory whose scattering matrix was obtained from a physical-based full wave numerical simulation by solving Maxwell's equations. The effects of top–bottom structure, layer thickness, frequency respons...

This paper presents an electromagnetic modeling of temporal variations of microwave backscatter from rice canopy based on radiative transfer theory to understand the complex microwave scattering mechanisms of rice crops at different growth stages. Model validation is made by a comparison with field measurements fromfour independent campaigns by gro...

Extensive urban land expansion and heavy industrialization have increased energy consumption and caused environmental problems, both of which present serious threats to humans. Consequently, improved land use efficiency and realization of green development are imperative. Based on a detailed analysis of spatialtemporal evolution of urban land use e...

In this paper, a physically based numerical electromagnetic approach, by solving Maxwell's equations, is developed to investigate the scattering and the emission from double-layered media, where both the top and bottom interfaces are random sastrugi surfaces with a random horizontal shift between the two corresponding negative-slope facets of both...

In this study, the terbium phosphate and ytterbium oxide were successfully introduced into SBA-15 by high temperature solid phase method, and got TbPO4-Yb2O3/SBA-15 composite materials. The luminescence properties of the prepared materials were studied by luminescence spectroscopy. The influences of Yb2O3 to Tb³⁺ luminescent properties have been st...

In this study, the sulfosalicylic acid (SSA)-Tb and Yb compound were systematically assembled into the pores of SBA-15 by hydrothermal method. The luminescence properties of the prepared materials were studied through luminescence spectra. The influences of the content of Yb3+ and Tb3+ on luminescent properties have been studied, and the luminescen...

Numerous works show the great potential of microwave remote sensing in assessing biophysical variables of rice plants. However, most studies are focusing on the backscattering character of rice canopy. Much lesser attention has been devoted to modeling bistatic scattering behavior of rice canopy. Therefore, this study aims to improve the understand...

For the first time, the order mesoporous zinc oxide was synthesized by soft template synthesis method. The Eu and La phosphate were introduced into the prepared mesoporous zinc oxide by high temperature solid phase method, and got the mesoporous rare earth/zinc oxide composite materials. The luminescence characters of the materials were studied. Th...

This paper investigates the bistatic scattering from randomly corrugated surfaces with irregular grooves. For a given incident wave, the surface fields and the scattered field were computed by the method of moments in which the rooftop basis function was used to account for fast phase changes due to steep surface slopes. The total scattered field i...

In this study, satellite synthetic aperture radar (SAR) image dataset spanning 15 years was acquired for temporal analysis of the shorelines changes. Focus is placed on how the natural forces impact on the coastline and sandbank changes. The waterlines were extracted from SAR images based on a wavelet correlator. Tidal and bathymetric data were use...

Predicting the levels of chlorophyll-a (Chl-a) is a vital component of water quality management, which ensures that urban drinking water is safe from harmful algal blooms. This study developed a model to predict Chl-a levels in the Yuqiao Reservoir (Tianjin, China) biweekly using water quality and meteorological data from 1999-2012. First, six arti...

This paper deals with the modeling of bistatic scattering from a randomly rough surface. An advanced integral equation model is presented by giving its general framework of model developments, model expressions, and predictions of bistatic scattering for various surface parameters. Extension work to improve the model accuracy is also reported in mo...

This paper presents an automated method to track cumulonimbus (Cb) clouds based on cloud classification and characterizes Cb behavior from FengYun-2C (FY-2C). First, a seeded region growing (SRG) algorithm is used with artificial neural network (ANN) cloud classification as preprocessing to identify consistent homogeneous Cb patches from infrared i...

Although cumulonimbus (Cb) clouds are the main source of precipitation in south China, the relationship between Cb cloud characteristics and precipitation remains unclear. Accordingly, the primary objective of this study was to thoroughly analyze the relationship between Cb cloud features and precipitation both at the pixel and cloud patch scale, a...

The crowning objective of this research are to analyze precipitation character of Cb for different dynamical characters in Huai river basin(HRB) with China's first operational geostationary meteorological satellite FengYun-2C (FY-2C) data. Firstly, 5 cloud patch dynamic parameters with respect to life stage and moving parameters are derived based o...

The crowning objective of this research was to identify a better cloud classification method to upgrade the current window-based clustering algorithm used operationally for China's first operational geostationary meteorological satellite FengYun-2C (FY-2C) data. First, the capabilities of six widely-used Artificial Neural Network (ANN) methods are...