Spectroscopy plays a major role in the access of the analytical parameters of the soil. It tends to substitute the conventional laboratory analysis because hyperspectral data were least expensive and easier to obtain....Spectroscopy plays a major role in the access of the analytical parameters of the soil. It tends to substitute the conventional laboratory analysis because hyperspectral data were least expensive and easier to obtain. The objective of this study was to evaluate the effect of the continuum removal (CR) in the validation of the accurate prediction model of the soil properties with Vis-NIR spectroscopy data. Few studies using Vis-NIR reflectance spectroscopy have well focused the calculation of the CR method;its effect in the calibration of the accurate models was also not well emphasized. In this study, we used the remote sensing software ENVI 4.7 to compute the CR function where the value of the continuum for each sample and for each spectral wavelength was obtained by dividing the reflectance values of the full spectrum (FS) with those of the continuum curve (CC). The partial least square regression (PLSR) model was applied in the spectral data from the soil of the Senegal Sahelian region. It was calibrated with both data from the full spectrum (FS) and those obtained after the application of the continuum removal. With the application of the CR, ultraviolet wavelengths (350 - 429 nm) and those of near infrared (2491 - 2500 nm) were removed from the explanatory variables of PLSR model. With the FS, all wavelengths between 350 and 2500 nm were taken into account in predicting soil properties. Our findings show a positive effect of the application of CR in the estimation of soil organic carbon. In calibration, the R2 increased up to 10% with the continuum removal in the model of 12 components (CP). In terms of validation, it’s the 15-component model which is the most accurate with the same range in calibration between the FS and the CR. The lowest RMSE ranged from 0.04 with the FS to 0.03 with the application of the CR in calibration and validation. These results show that the interest of this study as soil organic carbon is recognized as a key indicator of fertility of the soil in Sahelian-African regions. For future studies, it’s important to apply the model of neural networks to better evaluate the effect of continuum removal in predicting soil properties from the spectral data and other methods of preprocessing like the multiplicative scatter correction (msc).展开更多
河流及水库等水生态系统中的溶解性无机碳(DIC)是全球碳循环与大气、陆地和海洋之间碳相互作用的重要组成部分.以澜沧江云南段上游天然河段及下游梯级水库群形成的连续体为研究对象,分析了河库连续体表层水体中水化学特征、溶解性无机...河流及水库等水生态系统中的溶解性无机碳(DIC)是全球碳循环与大气、陆地和海洋之间碳相互作用的重要组成部分.以澜沧江云南段上游天然河段及下游梯级水库群形成的连续体为研究对象,分析了河库连续体表层水体中水化学特征、溶解性无机碳浓度及其碳同位素时空分布特征.研究结果表明:河库连续体水体中溶解无机碳(DIC)及其同位素(δ13 C DIC)组成特征总体表现为:DIC浓度丰水期较低,枯水期较高,平均值分别为2.59±0.44和3.30±0.37 mmol/L;δ13 C DIC值丰水期偏负、枯水期偏正,平均值分别为-8.52‰±0.38‰和-6.95‰±0.53‰,与自然河流的季节变化特征相似.水体DIC来源主要包括土壤及水体有机质分解生成的CO 2、碳酸盐风化和水气界面CO 2的交换过程.澜沧江河库连续体中DIC浓度及δ13 C DIC组成的时空异质性特征与流域岩性、土壤生物地球化学过程以及微生物活动强度等均有较大关系.当前,澜沧江梯级水库群建库时间短,梯级联合运行下调度复杂,水文条件多变,梯级水库对河流重要生源要素——碳累积影响方面的“水库效应”还不明显.展开更多
湿地植被制图是湿地自然资源管理过程中的一项重要任务。文中选取黄河口湿地为研究区,应用海岸带高光谱成像仪影像,提出了一种基于包络线去除的改进型光谱角匹配(Spectral Angle Mapper based on Continuum Removal,SAM_CR)方法,对芦苇...湿地植被制图是湿地自然资源管理过程中的一项重要任务。文中选取黄河口湿地为研究区,应用海岸带高光谱成像仪影像,提出了一种基于包络线去除的改进型光谱角匹配(Spectral Angle Mapper based on Continuum Removal,SAM_CR)方法,对芦苇、狄草、碱蓬和怪柳等湿地典型植被进行分类提取。结果表明,SAM_CR湿地典型植被种类识别的总体精度由传统SAM方法的74.87%提高到80.61%。展开更多
文摘Spectroscopy plays a major role in the access of the analytical parameters of the soil. It tends to substitute the conventional laboratory analysis because hyperspectral data were least expensive and easier to obtain. The objective of this study was to evaluate the effect of the continuum removal (CR) in the validation of the accurate prediction model of the soil properties with Vis-NIR spectroscopy data. Few studies using Vis-NIR reflectance spectroscopy have well focused the calculation of the CR method;its effect in the calibration of the accurate models was also not well emphasized. In this study, we used the remote sensing software ENVI 4.7 to compute the CR function where the value of the continuum for each sample and for each spectral wavelength was obtained by dividing the reflectance values of the full spectrum (FS) with those of the continuum curve (CC). The partial least square regression (PLSR) model was applied in the spectral data from the soil of the Senegal Sahelian region. It was calibrated with both data from the full spectrum (FS) and those obtained after the application of the continuum removal. With the application of the CR, ultraviolet wavelengths (350 - 429 nm) and those of near infrared (2491 - 2500 nm) were removed from the explanatory variables of PLSR model. With the FS, all wavelengths between 350 and 2500 nm were taken into account in predicting soil properties. Our findings show a positive effect of the application of CR in the estimation of soil organic carbon. In calibration, the R2 increased up to 10% with the continuum removal in the model of 12 components (CP). In terms of validation, it’s the 15-component model which is the most accurate with the same range in calibration between the FS and the CR. The lowest RMSE ranged from 0.04 with the FS to 0.03 with the application of the CR in calibration and validation. These results show that the interest of this study as soil organic carbon is recognized as a key indicator of fertility of the soil in Sahelian-African regions. For future studies, it’s important to apply the model of neural networks to better evaluate the effect of continuum removal in predicting soil properties from the spectral data and other methods of preprocessing like the multiplicative scatter correction (msc).
文摘河流及水库等水生态系统中的溶解性无机碳(DIC)是全球碳循环与大气、陆地和海洋之间碳相互作用的重要组成部分.以澜沧江云南段上游天然河段及下游梯级水库群形成的连续体为研究对象,分析了河库连续体表层水体中水化学特征、溶解性无机碳浓度及其碳同位素时空分布特征.研究结果表明:河库连续体水体中溶解无机碳(DIC)及其同位素(δ13 C DIC)组成特征总体表现为:DIC浓度丰水期较低,枯水期较高,平均值分别为2.59±0.44和3.30±0.37 mmol/L;δ13 C DIC值丰水期偏负、枯水期偏正,平均值分别为-8.52‰±0.38‰和-6.95‰±0.53‰,与自然河流的季节变化特征相似.水体DIC来源主要包括土壤及水体有机质分解生成的CO 2、碳酸盐风化和水气界面CO 2的交换过程.澜沧江河库连续体中DIC浓度及δ13 C DIC组成的时空异质性特征与流域岩性、土壤生物地球化学过程以及微生物活动强度等均有较大关系.当前,澜沧江梯级水库群建库时间短,梯级联合运行下调度复杂,水文条件多变,梯级水库对河流重要生源要素——碳累积影响方面的“水库效应”还不明显.
文摘湿地植被制图是湿地自然资源管理过程中的一项重要任务。文中选取黄河口湿地为研究区,应用海岸带高光谱成像仪影像,提出了一种基于包络线去除的改进型光谱角匹配(Spectral Angle Mapper based on Continuum Removal,SAM_CR)方法,对芦苇、狄草、碱蓬和怪柳等湿地典型植被进行分类提取。结果表明,SAM_CR湿地典型植被种类识别的总体精度由传统SAM方法的74.87%提高到80.61%。
