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A Method for Retrieving Water-leaving Radiance from landsat tm image in Taihu Lake, East China

Chinese Geographical Science 2007年第4期17卷 364-369页

作者： WANG Deyu FENG Xuezhi MA Ronghua KANG Guoding Department of Geographic and Information Science Nanjing University Nanjing 210093 China Nanjing Institute of Geography and Limnology Chinese Academy of Sciences Nanjing 210008 China Department of Demography and Economics Nanjing College for Population Programme Management Nanjing 210042 China

The visible and infrared bands of landsat Thematic Mapper （tm） can be used for inland water studies. A method of retrieving water-leaving radiance from tm image over Taihu Lake in Jiangsu Province of China was investigated in this article. To estimate water-leaving radiance, atmospheric correction was performed in three visible bands of 485nm, 560nm and 660rim. Rayleigh scattering was computed precisely, and the aerosol contribution was estimated by adopting the clear-water-pixels approach. The clear waters were identified by using the landsat tm middle-infrared band （2.1 μm）, and the water-leaving radiance of clear water pixels in the green band was estimated by using field data. Aerosol scattering at green band was derived for six points, and interpolated to match the tm image. Assuming the atmospheric correction coefficient was 1.0, the aerosol scattering image at blue and red bands were derived. Based on a simplified atmospheric radiation transfer model, the water-leaving radiance for three visible bands was retrieved. The water-leaving radiance was normalized to make it comparable with that estimated from other remotely sensed data acquired at different times, and under different atmospheric conditions. Additionally, remotely sensed reflectance of water was computed. To evaluate the atmospheric correction method presented in this article, the correlation was analyzed between the corrected remotely sensed data and the measured water parameters based on the retrieval model. The results show that the atmospheric correction method based on the image itself is more effective for the retrieval of water parameters from landsat tm data than 6S （Second Simulation of the Satellite Signal in the Solar Spectrum） code based on standard atmospheric and aerosol models.

关键词： retrieval method water-leaving radiance landsat tm image Taihu Lake

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Delineating suspended sediment concentration patterns in surface waters of the Changjiang Estuary by remote sensing analysis

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Acta Oceanologica Sinica 2010年第4期29卷 38-47页

作者： LI Jing GAO Shu WANG Yaping Ministry of Education Key laboratory for Coast and Island Development Nanjing University Nanjing 210093 China

Three landsat tm imageries （taken on 18 May 1987,4 August 1998 and 28 July 2007） were used as the data source to identify the spatial and temporal variations of the suspended sediment concentration （SSC） in surface waters of the Changjiang *** correction was carried out to determine the water-leaving reflectance using the FLAASH module.A regression equation between surveyed SSC and suspended sediment index was chosen to retrieve the SSC from the landsat tm *** addition,tidal harmonic analysis was performed to calculate tidal conditions corresponding to the acquisition time of satellite *** results show that the SSC spatial patterns are similar to the in situ observation results,which show the highest SSC in the region of turbidity maximum zone in the Changjiang *** the period of 1987 to 2007,the SSC pattern is controlled mainly by tidal dynamic conditions and wind speeds,rather than sediment discharges from the river.

关键词： suspended sediment concentration landsat tm image tidal conditions the Chang-jiang Estuary

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Estimating Soil Salinity in the Yellow River Delta, Eastern China——An Integrated Approach Using Spectral and Terrain Indices with the Generalized Additive Model

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Pedosphere 2016年第5期26卷 626-635页

作者： SONG Chuangye REN Hongxu HUANG Chong State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Key Laboratory of Plant Resources Institute of Botany Chinese Academy of Sciences Institute of Geographical Sciences and Natural Resources Chinese Academy of Sciences

Soil salinity is one of the most severe environmental problems worldwide. It is necessary to develop a soil-salinity-estimation model to project the spatial distribution of soil salinity. The aims of this study were to use remote sensed images and digital elevation model(DEM) to develop quantitative models for estimating soil salinity and to investigate the influence of vegetation on soil salinity estimation. Digital bands of landsat Thematic Mapper(tm) images, vegetation indices, and terrain indices were selected as predictive variables for the estimation. The generalized additive model(GAM) was used to analyze the quantitative relationship between soil salt content, spectral properties, and terrain indices. Akaike's information criterion(AIC) was used to select relevant predictive variables for fitted GAMs. A correlation analysis and root mean square error between predicted and observed soil salt contents were used to validate the fitted GAMs. A high ratio of explained deviance suggests that an integrated approach using spectral and terrain indices with GAM was practical and efficient for estimating soil salinity. The performance of the fitted GAMs varied with changes in vegetation *** in sparsely vegetated areas was estimated better than in densely vegetated areas. Visible red and near-infrared bands, and the second and third components of the tasseled cap transformation were the most important spectral variables for the estimation. Variable combinations in the fitted GAMs and their contribution varied with changes in vegetation cover. The contribution of terrain indices was smaller than that of spectral indices, possibly due to the low spatial resolution of DEM. This research may provide some beneficial references for regional soil salinity estimation.

关键词： Akaike's information criterion digital elevation model landsat tm image soil salt content terrain in indices vegetation cover

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维普期刊数据库

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Application of SAM and SVM Techniques to Burned Area Detection for landsat tm images in Forests of South Sumatra

Application of SAM and SVM Techniques to Burned Area Detecti...

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International Conference on Environmental Science and Technology（ICEST 2011）

作者： Ajeng Anggraeni Chinsu Lin Dept.of Forestry and Natural Resources National Chiayi University

Forest fires are an annual disaster which has become of international concern due to increased attention to environmental and economic issues in the last few *** fires cause damage that lead to annual decrease in *** is not only due to natural environmental conditions increasing the frequency of accidental forest fires（prolonged dry season or El Nino） but is also caused by clearing forest and peat land for palm oil plantation and HTI（timber production）.Lowland forests in Sumatra are now regarded as among the most threatened forests in the ***’s very important to detect and monitor forest *** sensing from space is especially suitable for forest fire *** data can be a very useful tool for mapping forest areas that have recently been *** tm images were used for target *** fire hot-spot data from MODIS were used as reference *** signature from burned area were then extracted and used for target detection analysis using a Spectral Angle Mapper（SAM） *** classification with Support Vector Machine（SVM） algorithm was also used for classifying the image as a burned *** goal of this study was to measure fire induced deforestation in South Sumatra,produce a burned area map from a landsat tm image and compare the efficiency of SAM and SVM techniques for burned area *** showed that SVM and SAM could reach an accuracy of 0.975 and 0.835 respectively,and it is suggested SVM might be more suitable for burned area mapping to be utilized in forest monitoring.

关键词： forest fire deforestation landsat tm image MODIS target detection burned area South Sumatra SVM algorithm SAM algorithm

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