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基于环境一号卫星的内陆水体水质多光谱遥感监测 总被引：5，自引：0，他引：5
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。 相似文献
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随着遥感技术的飞速发展,利用遥感数据来进行水资源的监测、调查和分析已经成为一种必然的趋势。通过选取新疆博湖县境内中国最大的内陆淡水湖-博斯腾湖为研究区,FY3A/MERSI影像为数据源,利用监督分类法从Landsat-ETM+影像提取水体,提取结果作为FY3A/MERSI影像水体提取精度验证的底图。采用单波段阈值法、基于阈值的多波段谱间关系法和基于阈值的水体指数法从FY3A/MERSI影像提取研究区水体,基于混淆矩阵法,提取结果分别与Landsat-ETM+影像底图作对比分析,最终得出结论,基于阈值的水体指数法中的归一化差异水体指数法提取研究区水体的总体精度最高,为96.37%,Khat为0.915。 相似文献
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基于混合光谱理论的太湖水体叶绿素a浓度提取 总被引：11，自引：3，他引：8
TM图象多波段数据作为遥感监测水体叶绿素a浓度的数据源,已有多种遥感定量模型与之对应,但主要还是以经验模型为主。利用TM数据首先采用特征波段比值方法,建立太湖水体合适的叶绿素a浓度反演的遥感定量模型。由于经验模型的缺陷性,还提出了基于TM数据的水体混合光谱分析模型,同时分析了端元光谱提取方法对模型求解的影响。通过计算叶绿素a浓度模型估算结果与实地测量数据的相关系数和均方根误差(RMSE),可以发现混合光谱分析模型也是水体叶绿素a浓度遥感估算的另一条佳径。 相似文献
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基于MODIS的青藏高原湖泊透明度遥感反演 总被引：2，自引：1，他引：1
湖泊透明度是湖泊水体性质的一个重要参数,是湖泊浮游生物和进入湖泊的有机和无机颗粒溶解程度的综合反映,对湖泊生态环境研究具有重要的科学及实践意义。遥感影像是获取面积广、时间长的湖泊透明度的重要手段,但由于实测数据缺乏,目前对青藏高原地区湖泊透明度的遥感反演研究相对不足。本文基于青藏高原地区24个湖泊实测透明度SD(Secchi Depth)值和相应的MODIS遥感影像,建立了该地区湖泊水体透明度SD值MODIS遥感反演模型。结果表明：基于MODIS绿色波段B4的单波段幂函数模型在该地区反演效果最好,精度较高(R2=0.91, N=24),并具有较好的稳定性。以当惹雍错为例,选用该模型反演得到湖泊透明度的时间变化序列,发现该湖存在明显的季节波动和较为明显的年际变化。初步分析得出,降水/融水季节的湖泊透明度与湖泊所在流域的降水率具有密切的关系。本文结果表明,利用遥感手段能够有效地开展青藏高原地区湖泊透明度的反演,可为进一步深入研究该地区湖泊透明度及其影响要素奠定基础。 相似文献
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土壤砂粒含量是表征土壤质量的重要指标,探索建立基于高光谱遥感的区域土壤砂粒含量反演方法对区域土壤质量监测具有重要意义。通过野外采集的高光谱数据与MODIS影像相结合,遴选出土壤砂粒含量的敏感波段与反演方程,进行干旱区裸地土壤砂粒含量遥感反演研究。结果表明：430 nm为土壤砂粒含量的敏感波段,原始光谱经变换后的数值与土壤砂粒含量的相关系数在430 nm处达到最大值0.76;基于MODIS第3波段中心波长460 nm处的土壤原始光谱的反演精度最高,达到89.30%,与实际情况吻合较好,表明MODIS第3波段可以应用于干旱区裸地土壤砂粒含量的遥感反演。 相似文献
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基于TM数据的太湖叶绿素A浓度定量反演 总被引：21，自引：2，他引：19
利用TM(ETM)数据与准实时地面采样数据,建立太湖叶绿素浓度反演模型。结果表明,TM3/(TM1+TM4)与叶绿素A浓度的相关性最好,并以此建立了太湖叶绿素A浓度线性反演模型,但反演精度并不高,因此,建立了一个两层BP神经网络模型反演太湖的叶绿素A浓度,结果表明,神经网络模型的反演精度远高于线性反演模型,16个测试样本表明,神经网络模型反演的相对误差小于30%的有15个点,占总测试样本93.75%,而线性反演模型反演相对误差在30%以下的仅有3个点,这表明对于太湖这样一个光谱特征复杂的二类水体,可以利用神经网络模型反演水质参数。 相似文献
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K-T变换在监测小麦地表参数中的应用 总被引：1，自引：0，他引：1
利用K-T变换提取TM和MODIS遥感影像的绿度、湿度分量,在不同的分辨率尺度下监测小麦覆盖地表参数:土壤湿度(Ms)、等效水厚度(EWT)和叶面积指数(LAI),并与NDVI(归一化植被指数)、NDWI(归一化水分指数)和EVI(增强植被指数)监测结果比较.湿度分量监测Ms效果更好,TM和MODIS遥感影像反演精度分别为6.08%、7.37%(RMSE),相关系数R2分别为0.49、0.31,基于绿度和湿度分量建立土壤湿度多元线性回归反演模型,利用TM影像反演土壤湿度RMSE为4.91%,反演土壤湿度和实测土壤湿度R2达0.63;绿度分量监测EWT效果更好,TM和MODIS遥感影像反演精度分别为0.37 kg/m2、0.43 kg/m2,R2分别为0.51、0.28;绿度分量反演LAI精度更好,TM和MODIS遥感影像反演精度分别为0.66、0.83,R2分别为0.64、0.35. 相似文献
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基于CBERS-02 IRMSS和MODIS数据的地表温度反演与热环境评价 总被引：2，自引：0，他引：2
应用中巴资源卫星热红外遥感数据(CBERS-02 IRMSS)和普适性单通道算法反演福州市的地表温度.反演过程中使用同时相的MODIS数据在像元尺度上获取的大气水汽含量替换标准大气模拟值,参考气候资源评价中人体舒适度指数模型,建立基于地温的热环境评价模型,并对福州城市热环境进行评级.结果表明:中巴资源卫星热红外数据对城市热岛和热环境研究具有重要的应用价值,多源遥感数据的结合可以提高地表温度的反演精度,而基于遥感反演参数的热环境指数评价方法能够较好地描述城市热环境的空间特征. 相似文献
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基于Hyperion数据的南四湖叶绿素浓度反演研究 总被引：2，自引：0，他引：2
通过对2005年5月7日南四湖Hyperion高光谱影像的几何纠正和6S模型辐射校正,以及水体光谱数据分析,对22个水体样点原始光谱数据分别采用归一化处理和包络线消除处理后,以波段比值数据构建叶绿素浓度反演模型,选取相关系数最大的反演模型,获得南四湖叶绿素浓度的空间分布图。研究表明,包络线消除法能很好地去除水体的光谱曲线背景影响,突出光谱曲线的吸收和反射特征,与归一化处理相比,反演模型的相关系数都有很大提高。R700/R560波段比值数据构建的模型相关性最高,相关系数为0.834,可用于叶绿素浓度反演研究。 相似文献
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We present a simple method to derive spatial precipitation (P) and evapotranspiration (ET) for the typical steppe of the Xilin river catchment at 1 km and 8-day resolution during the main vegetation period (23 April to 28 August) of 2006. The hydrological model BROOK90 was parameterised from eddy covariance measurements. The daily model input data, precipitation, minimum (Tamin) and maximum air temperature (Tamax), were derived by manipulating MODIS leaf area index (LAI) and surface temperature data. P was estimated based on a linear regression of P measured at several sites against the mean gain of the MODIS LAI of surrounding 3 × 3 pixels areas (R2 = 0.76). Tamin and Tamax were derived using a relationship between measured Tamin and Tamax and MODIS surface temperatures (R2 = 0.92 and R2 = 0.88, respectively). The mean precipitation was 145 mm; it varied between 52 mm in the north-western region and 239 mm in the eastern region. In spring, the modelled ET was low (<0.8 mm d−1); evaporation dominated over transpiration and spatial differences were small. At the end of June, the mean ET reached its maximum (2 mm d−1) and spatial differences were pronounced. From July on, transpiration dominated over declining evaporation, and spatial differences decreased in August. 相似文献
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青藏高原生态系统固碳释氧价值动态测评 总被引：6，自引：1，他引：5
本文旨在定量评价青藏高原生态系统的固碳释氧价值及其动态变化,为改善区域生态环境提供参考。基于MODIS/NDVI数据,利用光能利用率模型测算净第一性生产(NPP)物质量,并通过光合作用方程式换算成固定CO2和释放O2的物质量,以此为基础,采用造林成本法和工业制氧法对青藏高原固碳释氧价值量进行估算。结果表明:2000年、2005年和2010年固定CO2的价值分别为384.36×109元、393.23×109元和356.41×109元,释放O2的价值分别为408.31×109元、415.02×109元和378.61×109元。2000-2005年固碳释氧价值增加了15.58×109元,2005-2010年下降了73.23×109元,而2000-2010年下降了57.65×109元。固碳释氧价值在空间上呈现出从东南向西北递减的趋势,这与青藏高原的水热条件分布基本一致。在价值构成中,草原>森林>草甸>其它类型>灌丛>农田。2000-2010年青藏高原生态系统固碳释氧价值呈现减小趋势,表明近年来气候变化和人类活动导致青藏高原的生态环境出现了退化趋势。 相似文献
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气候变化对河北省海河流域径流量的影响 总被引：2，自引：0，他引：2
利用河北省境内海河流域51个气象站、68个水文站1956~2000年近50年的气象、径流量数据,分析了气象要素和径流量的变化规律。河北省境内海河流域多年平均地表径流量为67.0×108m3,从20世纪 50 年代至 90 年代地表径流量呈逐渐减小的趋势,50年代为105.3×108m3,90年代为54.7×108m3。地表径流量随降水量的减少而减小,随气温的升高而下降,用回归方法建立的径流量与气象要素之间的模型为对数模型。根据未来气候变化情景对河北省海河流域径流量的预测:2030年为70.0~76.8×108m3,2050年为69.8~76.9×108m3。 相似文献
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Annual above-ground net primary production (ANPP), evapotranspiration (ET) and water use efficiency (WUE) of rangeland have the potential to provide an objective basis for establishing pricing for ecosystem services. To provide estimates of ANPP, we surveyed the biomass, estimated ET and prepared a water use efficiency for dwarf shrublands and arid savanna in the Riemvasmaak Rural Area, Northern Cape, South Africa. The annual production fraction was surveyed in 33 MODIS 1 km2 pixels and the results regressed against the MODIS fPAR product. This regression model was used to predict the standing green biomass (kg DM ha−1) for 2009 (dry year). Using an approach which combines potential evapotranspiration (ET0) and the MODIS fPAR product, we estimated actual evapotranspiration (ETa). These two models (greening standing biomass and ETa) were used to calculate the annual WUE for 2009. WUE was 1.6 kg DM mm−1 ha−1 yr−1. This value may be used to provide an estimate of ANPP in the absence of direct measurements of biomass and to provide a comparison of the water use efficiency of this rangeland with other rangeland types. 相似文献
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Julien M.J. Racca Aline Philibert Robert Racca Yves T. Prairie 《Journal of Paleolimnology》2001,26(4):411-422
We explored the possibility of using artificial neural networks (ANN) to develop quantitative inference models in paleolimnology. ANNs are dynamic computer systems able to learn the relations between input and output data. We developed ANN models to infer pH from fossil diatom assemblages using a calibration data set of 76 lakes in Quebec. We evaluated the predictive power of these models in comparison with the two most commonly methods used in paleolimnology: Weighted Averaging (WA) and Weighted Averaging Partial Least Squares (WA-PLS). Results show that the relationship between species assemblages and environmental variables of interest can be modelled by a 3-layer back-propagation network, with apparent R2 and RMSE of 0.9 and 0.24 pH units, respectively. Leave-one-out cross-validation was used to access the reliabilities of the WA, WA-PLS and ANN models. Validation results show that the ANN model (R2
jackknife = 0.63, RMSEjackknife = 0.45, mean bias = 0.14, maximum bias = 1.13) gives a better predictive power than the WA model (R2
jackknife = 0.56, RMSEjackknife = 0.5, mean bias = –0.09, maximum bias = –1.07) or WA-PLS model (R2
jackknife = 0.58, RMSEjackknife = 0.48, mean bias = –0.15, maximum bias = –1.08). We also evaluated whether the removal of certain taxa according to their tolerance changed the performance of the models. Overall, we found that the removal of taxa with high tolerances for pH improved the predictive power of WA-PLS models whereas the removal of low tolerance taxa lowered its performance. However, ANN models were generally much less affected by the removal of taxa of either low or high pH tolerance. Moreover, the best model was obtained by averaging the predictions of WA-PLS and ANN models. This implies that the two modelling approaches capture and extract complementary information from diatom assemblages. We suggest that future modelling efforts might achieve better results using analogous multi-model strategies. 相似文献
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The spatio-temporal pattern of the global water resource has significantly changed with climate change and intensified human activities. The regional economy and ecological environment are highly affected by terrestrial water storage (TWS), especially in arid areas. To investigate the variation of TWS and its influencing factors under changing environments, the response relationships between TWS and changing environments (climate change and human activities) in Central Asia have been analyzed based on the Gravity Recovery and Climate Experiment (GRACE) data, Climatic Research Unit (CRU) climate data and Moderate Resolution Imaging Spectroradiometer (MODIS) remote sensing data products (MOD16A2, MOD13A3 and MCD12Q1) from 2003 to 2013. The slope and Pearson correlation analysis methods were used. Results indicate that: (1) TWS in about 77 % of the study area has decreased from 2003 to 2013. The total change volume of TWS is about 2915.6 × 108 m3. The areas of decreased TWS are mainly distributed in the middle of Central Asia, while the areas of increased TWS are concentrated in the middle-altitude regions of the Kazakhstan hills and Tarim Basin. (2) TWS in about 5.91% of areas, mainly distributed in the mountain and piedmont zones, is significantly positively correlated with precipitation, while only 3.78% of areas show significant correlation between TWS and temperature. If the response time was delayed by three months, there would be a very good correlation between temperature and TWS. (3) There is a significantly positive relationship between TWS and Normalized Difference Vegetation Index (NDVI) in 13.35% of the study area. (4) The area of significantly positive correlation between TWS and evapotranspiration is about 31.87%, mainly situated in mountainous areas and northwestern Kazakhstan. The reduction of regional TWS is related to precipitation more than evaporation. Increasing farmland area may explain why some areas show increasing precipitation and decreasing evapotranspiration. (5) The influences of land use on TWS are still not very clear. This study could provide scientific data useful for the estimation of changes in TWS with climate change and human activities. 相似文献
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采用动态密闭气室法测定分析了科尔沁沙地典型玉米(Zea mays)农田垄上和垄间土壤呼吸速率的差异及自养和异养呼吸特征,并估算了生态系统碳平衡。结果表明:(1)垄上和垄间土壤呼吸速率存在极显著差异(p0.001),且存在线性关系(p0.05);季节水平上垄上土壤呼吸可解释垄间土壤呼吸98.4%的变异。(2)季节水平上土壤总呼吸(RS)、异养呼吸(RH)和自养呼吸(RA)的温度敏感性指数Q10大小顺序为:RA(4.35)RS(3.10)RH(2.08)。(3)RS和RH之间存在显著差异,RA与RS和RH之间不存在显著差异;RA占RS比例的季节变化范围为28.1%~71.1%,生长季RH和RA占RS的比例均值分别为44.4%和55.6%。(4)科尔沁沙地典型农田生态系统在生长季为碳汇,可净固存大气CO2-C的量为659.1g·m-2。 相似文献
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Artificial Neural Networks in Proglacial Discharge Simulation: Application and Efficiency Analysis in Comparison to the Multivariate Regression; A Case Study of Waldemar River (Svalbard) 
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下载免费PDF全文 Artificial neural networks were applied to simulate runoff from the glacierized part of the Waldemar River catchment (Svalbard) based on hydrometeorological data collected in the summer seasons of 2010, 2011 and 2012. Continuous discharge monitoring was performed at about 1 km from the glacier snout, in the place where the river leaves the marginal zone. Averaged daily values of discharge and selected meteorological variables in a number of combinations were used to create several models based on the feed‐forward multilayer perceptron architecture. Due to specific conditions of melt water storing and releasing, two groups of models were established: the first is based on meteorological inputs only, while second includes the preceding day's mean discharge. Analysis of the multilayer perceptron simulation performance was done in comparison to the other black‐box model type, a multivariate regression method based on the following efficiency criteria: coefficient of determination (R2) and its adjusted form (adj. R2), weighted coefficient of determination (wR2), Nash–Sutcliffe coefficient of efficiency, mean absolute error, and error analysis. Moreover, the predictors' importance analysis for both multilayer perceptron and multivariate regression models was done. The performed study showed that the nonlinear estimation realized by the multilayer perceptron gives more accurate results than the multivariate regression approach in both groups of models. 相似文献
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基于MODIS影像的土地覆被分类研究——以京津冀地区为例 总被引：6，自引：1，他引：5
在全球变化研究中,如何快速、准确获取土地覆被信息对该项研究有着至关重要的作用.随着遥感科学的不断发展和应用领域的深入,研究者可以利用遥感影像进行土地覆被分类研究,并且具有准确、快速、自动化等优点.本文利用MODIS数据具有的多光谱、多时相特点,以京津冀地区为例,选取2013 年全年16-day 的MOD13Q1/EVI时间序列数据、2013 年5 月份一期的MOD09Q1(1、2 波段)和MOD09A1(3-7 波段)产品,并运用时间序列谐波分析法对全年MOD13Q1/EVI 时间序列数据进行去云、去噪的平滑重建处理,使其数据更能反映物候周期性变化规律.选择谐波分析后的全年MOD13Q1/EVI 时间序列数据、MODIS数据的1-7 波段地表反射率和NDWI(归一化差异水体指数)、MNDWI(改进归一化差异水体指数)和NDSI(土壤亮度指数),构建了3 种特征变量组合方案的CART决策树,分别进行京津冀地区的土地覆被分类研究.结果表明:方案一(全年EVI 的23 个时相)、方案二(方案一+MOD09 的1-7 波段地表反射率)和方案三(方案二+MNDWI+NDSI+NDWI)的总体分类精度分别达到86.70%、89.98%、91.34%,Kappa系数分别为84.94%、88.66%、90.20%.研究表明,仅利用MODIS遥感影像自身多种分类特征和决策树方法对宏观土地覆被分类就可达到较高精度,显示了本文分类方法在实践中的可行性及MODIS数据在区域尺度土地覆被分类研究方面的优势与潜力. 相似文献
20.
北京市水资源与水量平衡研究 总被引：4，自引：1，他引：3
以降雨-径流-蒸散发平衡和水资源供需平衡模式为基础进行研究,得到以下结论:北京市2001～2009年系列的水资源量与多年平均系列相比,水资源产量减少了约40.1%,减少的原因既有气候因素,也有人类活动导致土地覆被变化的原因,其中气候因素占30.1%,下垫面变化导致产流减少的比重为69.9%;同时由于人口的增长,北京市人均水资源占有量从270 m3下降到114 m3.在北京市水平衡分析中,采用不同下垫面蒸散发模式,计算得到2001～2009年北京市蒸散发为494 mm,河川径流量为46 mm,入境水量为4.34 亿m3,出境水量为8.03 亿m3,超采地下水、水库净补给以及外流域引水量为6.19 亿m3.在不考虑河道内生态需水条件下,北京市的现状缺水量为4.73～5.86 亿m3.到2014年南水北调中线水到达北京以后,北京将可以在75%来水年份下保障10～15年的水资源的基本供需平衡。但是如果遭遇95%来水频率的特枯年份,北京仍然将会面临较为严重的水资源短缺问题。 相似文献