Prediction of chlorophyll a concentration using HJ-1 satellite imagery for Xiangxi Bay in Three Gorges Reservoir

Since the impoundment of the Three Gorges Reservoir in 2003, algal blooms have frequently been observed in it. The chlorophyll a concentration is an important parameter for evaluating algal blooms. In this study, the chlorophyll a concentration in Xiangxi Bay, in the Three Gorges Reservoir, was predicted using HJ-1 satellite imagery. Several models were established based on a correlation analysis between in situ measurements of the chlorophyll a concentration and the values obtained from satellite images of the study area from January 2010 to December 2011. Chlorophyll a concentrations in Xiangxi Bay were predicted based on the established models. The results show that the maximum correlation is between the reflectance of the band combination of B4/（B2＋B3） and in situ measurements of chlorophyll a concentration. The root mean square errors of the predicted values using the linear and quadratic models are 18.49 mg/m3 and 18.52 mg/m3, respectively, and the average relative errors are 37.79% and 36.79%, respectively. The results provide a reference for water bloom prediction in typical tributaries of the Three Gorges Reservoir and contribute to large-scale remote sensing monitoring and water quality management.

基于HJ-1的长汀县森林绿量分析

以福建省长汀县为研究对象,采用3S技术对长汀2012年3月环境资源卫星HJ-1 CCD影像进行处理,依据树种光谱灰度阈值的差异将研究区林木按杉木、松木、竹、阔叶树进行分类,并实测叶面积指数(LAI),计算出长汀县森林绿量。研究结果表明,长汀县有林地面积所占比例为86.62%,总绿量为768 781.2 hm2,其中三州镇、河田镇等乡镇绿量分布属于低水平,铁长乡、庵杰乡等乡镇绿量分布处于较高水平,结合当地水土流失现状发现森林绿量与水土流失程度总体呈负相关。研究结论可为该区域的森林合理经营和可持续发展提供决策支持。

基于HJ-1遥感数据的矿区水体污染监测与分析——以龙岩紫金山金铜矿为例

矿产资源的持续开采与加工利用使得矿区周边水资源受到的污染日趋严重,急需采用先进技术对水污染进行监测分析,遥感技术是水环境监测最为有效的技术之一。利用国产环境一号小卫星多光谱遥感影像数据,针对福建省龙岩市紫金山矿区不同时相的数据进行水质遥感监测。利用近红外单波段阈值分割法提取悬浮物浓度信息,基于矿区酸碱性水体光谱曲线特性采用342波段假彩色合成影像,采用SVM分类方法进行分类,判别矿区水体酸碱性以及分析水体受污染程度变化和污染源。结果表明,研究区汀江水体2008年呈现碱性,2010年呈现弱碱性,水质在研究时段内得到一定的改善,但在选矿厂与矿区附近的水体中仍含有大量重金属沉积物。

基于HJ-1-A卫星CCD相机遥感影像的水体提取

采用面向对象的分析方法(object based image analysis,OBIA),结合水体特征对国产环境卫星(HJ-1-A)CCD相机影像的水体信息进行快速分析、处理和提取.结果表明,对于中低分辨率多光谱遥感影像水体信息的提取,该方法的提取精度在95%以上,优于最小距离法(minimum distance).

Comparative analysis of GF-1,HJ-1,and Landsat-8 data for estimating the leaf area index of winter wheat

Using simultaneously collected remote sensing data and field measurements, this study firstly assessed the consistency and applicability of China high-resolution earth observation system satellite 1 （GF-1） wide field of view （WFV） camera, environment and disaster monitoring and forecasting satellite （H J-l） charge coupled device （CCD）, and Landsat-8 opera- tional land imager （OLI） data for estimating the leaf area index （LAI） of winter wheat via reflectance and vegetation indices （VIs）. The accuracies of these LAI estimates were then assessed through comparison with an empirical model and the PROSAIL radiative transfer model. The effects of radiation calibration, spectral response functions, and spatial resolution on discrepancies in the LAI estimates between the different sensors were also analyzed. The results yielded the following observations： （1） The correlation between reflectance from different sensors is relative good, with the adjusted coefficients of determination （R2） between 0.375 to 0.818. The differences in reflectance are ranging from 0.002 to 0.054. The correlation between VIs from different sensors is high with the R2 between 0.729 and 0.933. The differences in the VIs are ranging from 0.07 to 0.156. These results show the three sensors＇ images can all be used for cross calibration of the reflectance and VIs. （2） The four VIs from the three sensors are all demonstrated to be highly correlated with LAI （R2 between 0.703 and 0.849）. The linear models associated with the 2-band enhanced vegetation index （EVI2）, which feature the highest R2 （higher than 0.746） and the lowest root mean square errors （RMSE） （less than 0.21）, were selected to estimate the winter wheat LAI. The accuracy of the estimated LAI from Landsat-8 was the highest, with the relative errors （RE） of 2.18% and an RMSE of 0.13, while the H J-1 was the lowest, with the RE of 2.43% and the RMSE of 0.15. （3） The inversion errors in the different sensors＇ LAI estimates using the PROSAIL model are small. The accuracy of the GF-1 is the highest with the RE of 3.44%, and the RMSE of 0.22, whereas that of the H J-1 is the lowest with the RE of 4.95%, and the RMSE of 0.26. （4） The effects of the spectral response function and radiation calibration for the different sensors are small and can be ignored, but the effects of spatial resolution are significant and must be taken into consideration in practical applications.

Global hypomethylation in hepatocellular carcinoma and its relationship to aflatoxin B_1 exposure

AIM:To determine global DNA methylation in paired hepatocellular carcinoma(HCC) samples using several different assays and explore the correlations between hypomethylation and clinical parameters and biomarkers,including that of aflatoxin B 1 exposure.METHODS:Using the radio labeled methyl acceptance assay as a measure of global hypomethylation,as well as two repetitive elements,including satellite 2(Sat2) by MethyLight and long interspersed nucleotide elements(LINE1),by pyrosequencing.RESULTS:By all three assays,mean methylation levels in tumor tissues were significantly lower than that in adjacent tissues.Methyl acceptance assay log(mean ± SD) disintegrations/min/ng DNA are 70.0 ± 54.8 and 32.4 ± 15.6,respectively,P = 0.040;percent methylation of Sat2 42.2 ± 55.1 and 117.9 ± 88.8,respectively,P < 0.0001 and percent methylation LINE1 48.6 ± 14.8 and 71.7 ± 1.4,respectively,P < 0.0001.Aflatoxin B 1 albumin(AFB 1-Alb) adducts,a measure of exposure to this dietary carcinogen,were inversely correlated with LINE1 methylation(r =-0.36,P = 0.034).CONCLUSION:Consistent hypomethylation in tumor compared to adjacent tissue was found by the three different methods.AFB 1 exposure is associated with DNA global hypomethylation,suggesting that chemical carcinogens may influence epigenetic changes in humans.

Operation and Application of A,B Satellites for Environment and Disaster Monitoring and Forecasting

Environment and disaster monitoring and forecasting small satellite constellation A and B satellites(HJ-1-A,B) are called "environment and disaster reduction satellites A and B" for short.The constellation adopts a 10:30LT sun-synchronous circular orbit,with orbit altitude of 649km.HJ1-A and HJ-1-B are distributed with a phase difference of 180° in the same orbital plane,so as to enhance the time resolution of earth observation.The satellites have orbit maintenance capability,the lifetime is 3 years.Both satellites adopt CAST968 platforms.Two wide-coverage multispectral CCD cameras with resolution 30m and width 700km,a super-spectral imager with resolution 100m and width 50km as well as a data transmission subsystem of 120Mbit/s are deployed on HJ-1-A,which also carries Ka communication testing equipment of Thailand.HJ-1-B has two wide-coverage multispectral CCD cameras(the same as satellite A),one infrared camera with resolution 150m and width 720km and a data transmission subsystem of 60Mbit/s.The coverage period of the wide-coverage multispectral CCD camera is 48 hours.The revisit period of super-spectral imager is 96 hours and the coverage period ofinfrared camera is 96 hours.

环境一号卫星及其在环境监测中的应用

2008年9月发射的环境一号卫星是中国自主研发的首颗专门用于环境与灾害监测的新型卫星,对中国环境遥感监测技术发展与应用具有里程碑意义。围绕环境一号卫星应用关键技术研究与业务运行,首先对在大量研究基础上形成的环境一号卫星技术性能指标进行了介绍和分析,给出了环境一号卫星CCD、红外和超光谱数据的实例,并从几何精度和辐射特性等多个方面对环境一号卫星数据质量进行了分析和评价;然后从大型水体环境遥感监测、区域环境空气遥感监测、宏观生态环境遥感监测的角度,系统提出了环境一号卫星的应用需求;在此基础上设计了包括业务流程和数据产品定义在内的环境一号卫星应用方案;最后将所建立的基于环境一号卫星的环境参数反演方法用于京津塘地区气溶胶光学厚度及巢湖叶绿素a浓度反演,显示了环境一号卫星应用的作用和效果。

基于光谱分类的总悬浮物浓度估算

总悬浮物浓度是水质评价的重要参数之一,传统的遥感反演估算模型忽视了光学性质多变、复杂的二类水体的差异性。本研究基于太湖、巢湖的星地同步实验,针对环境1号卫星多光谱数据,设立了水体光学分类方法,将研究水体分为二种类型,进而建立了适用于不同类型水体总悬浮物浓度的反演估算模型。得出以下结论:(1)基于光谱分类的方法可以提高总悬浮物浓度的反演估算精度;(2)对于类型一和类型二水体,分别使用指数模型和线性模型可以较好地反映总悬浮物浓度与反演估算因子之间的关系。

基于环境一号卫星的内陆水体水质多光谱遥感监测

基于环境一号卫星多光谱数据,针对我国内陆水体开展遥感监测研究。该研究建立分地区分季节经验模型反演叶绿素a浓度,基于生物光学模型的近红外单波段方法反演悬浮物浓度,以悬浮物浓度间接反演透明度,最终基于叶绿素a和悬浮物获得基于遥感监测的内陆水体营养状态指数。以2009年6月巢湖同步观测试验验证本文的水质参数反演算法,表明叶绿素a浓度反演精度不如悬浮物浓度,两者反演精度符合水环境监测业务需求。

环境一号卫星CCD数据在生态环境监测和评价工作中的应用价值研究

基于环境一号卫星CCD传感器性能,从生态景观角度入手,针对江苏省地形地貌特征,开展了环境一号卫星CCD数据在生态环境监测和评价工作中的应用可行性研究,结果表明环境一号卫星CCD数据可以满足江苏省生态环境监测和评价工作需要,其时间分辨率和幅宽是开展生态监控和预警的重要优势。

基于环境一号卫星的东洞庭湖富营养化评价

水体富营养化现象是一个世界性的水污染治理难题。洞庭湖是我国第二大淡水湖,其富营养化问题也慢慢变成一个阻碍当地经济发展的瓶颈。保护洞庭湖湿地生态环境,控制湖水富营养化,是洞庭湖区环境治理的首要任务。本文利用遥感技术,对环境一号卫星CCD遥感数据进行了处理,并从处理后的遥感图像中识别了2009年6月~10月东洞庭湖水体富营养化状况,并与实测数据计算综合营养状况指数对识别的结果进行对比,结果表明对遥感图像进行识别的结论与实地测量的情况基本一致,证明了环境一号卫星数据在湖泊水质遥感监测中的适用性。通过对东洞庭湖水质作出全面评价,为洞庭湖的水体生态环境保护提供了重要的理论基础。