Zheng Lanfen

Relating soil surface moisture to reflectance

Abstract The objective of this study was to explore the relationship between soil reflectance in the solar domain (400–2500 nm) and soil moisture. Ten soils covering a large range of composition have been sampled. To decrease the large dimensionality of the data set, we reduced the number of wavebands investigated thanks to a simple stepwise linear regression. Seven wavebands were selected, which represent the whole spectral domain for the 10 soils and all moisture conditions with a root mean square error (RMSE) better than 0.002, close to the experimental uncertainties. Each soil reflectance spectrum was normalized by the corresponding reflectance spectrum observed under the driest condition. This allows to minimize effects due to soil type, as well as those of other undesirable multiplicative factors such as roughness and measurement configuration. The relationship between the normalized soil reflectance and moisture was then investigated. For all the wavelengths and all the soils, results show that for low soil moisture levels, the reflectance decreased when the moisture increased. Conversely, after a critical point, soil reflectance increased with soil moisture. For some soils, the reflectance of the wettest conditions can overpass that of the driest conditions. The position of the critical point was related to soil hydrodynamic properties. For both low and high soil moisture levels, and the seven wavelengths selected, the relative reflectance was strongly correlated with moisture. Adjustment of the relationships over individual soil types provides better soil moisture retrieval performances. It also shows that the relationships are generally nonlinear. These results are discussed with regards to the underlying physical processes, as well as for application to soil moisture estimates from reflectance measurements.

A new architecture for Remote-Sensing Environmental Monitoring System REMS: design and implementation

A new architecture for REMS (Remote-sensing Environmental Monitoring System V1.0) is introduced in this paper. REMS is the first integrated system in China developed to meet the multi-resource, multi-temporal and multi-thematic data processing, analyzing and products distributing, especially to process and monitor inland water resource pollution. The most important components of REMS are presented in this paper including tools for multi-resource data input/output, preprocessing, data visualization and mapping, environment information extraction, conventional image analysis, advanced tools for eco-environment modeling, and integrated interface to connect with general spatial and spectral database and water quality monitoring database. REMS provide professional ability to extract the major characters of water resource such as Chlorophyll content, Total Suspended Matter (TSM), Yellow Substance or CDOM etc. In order to retrieve and predict the blue algae distribution and water quality evolvement, a group of statistical algorithms are also realized to analyses the result and at the same time data assurance measures are also given respectively. Finally, we select the Taihu Lake, JiangShu Province, South China, as the representative research area and some field applications constructed based on REMS are discussed

An operational method for fast detecting abnormal channels in imaging spectrometers

Data from abnormal channels in an imaging spectrometer almost always exerts an undesired impact on spectrum matching, classification, pattern recognition and other applications in hyperspectral remote sensing. To solve this problem, researchers should get rid of the data acquired by these channels. Selecting abnormal channels just in the way of visually examining each band image in a imaging data set is a conceivably hard and boring job. To relieve the burden, this paper proposes a method which exploits the spatial and spectral autocorrelations inherent in imaging spectrometer data, and can be used to speed up and, to a great degree, automate the detection of abnormal channels in an imaging spectrometer. This method is applied easily and successfully to one PHI data set and one Hymap data set, and can be applied to remotely sensed data from other hyperspectral sensors.

Mineral exploration by use of infrared multispectral remote sensing in China

A new airborne infrared multispectral technology has been used for study of the gold and other mineral exploration in the North-Western Part of China during past few years.In this study the following steps were involved:the measurements and analysis of spectral character-istics, airborne remote sensing data acquisition and processing , extracting information on mineralized features and the assessment of techniques.