排序方式： 共有24条查询结果，搜索用时 0 毫秒
1.
This study demonstrates the use of ASTER data for the mapping of gypsum deposits and associated geological formations that occurred in the Thumrait region of southern Oman. The measurement of spectra over samples of gypsum in the 1,300–2,500 nm wavelength using a PIMA spectrometer showed the presence of distinct absorptions at 1400–1600, 1750, 1940, 2,100, and 2,400 nm characteristics to O? H stretching, H2O combinations, and S? O bending overtones and stretching, respectively. Studying the unique spectral absorption characters of gypsum samples, we developed a false color composite (FCC) and an image by decorrelation stretch using the spectral bands 7, 3, and 2 of ASTER. The results FCC showed the regions of gypsum occurrences, and the decorrelated image discriminated the gypsum occurrences from other geological formations of the area. The study of surface mineralogy of the region using the VNIR‐SWIR bands by the spectral angle mapper method showed the presence of sulfate, carbonate, and clay minerals of the geological formations in the study area. We compared the results of ASTER with the results obtained using spectral bands 12, 8, and 4 of Sentinel‐2A processed by the same methods. The study showed that the spectral bands of ASTER can be used for mapping the gypsum and associated geological formations. 相似文献
2.
云南省作为我国西南地区与西藏相连的省份,其地势由西北向东南逐渐降低且山峦众多,山区面积占全省面积的88%。除此之外,云南省还位于印度洋板块和亚欧板块交界处附近,其地震带众多,地质运动频繁,经常出现地震、滑坡、泥石流等地质灾害。因此,本文选取覆盖地势较高的云南西北部地区的哨兵数据,利用SBAS-InSAR技术进行数据处理,针对云南西北部地区的地表形变进行监测,发现地质灾害隐患区域,为地质灾害预警提供数据支持。 相似文献
3.
It is important to identify and locate glacial lakes for assessing any potential hazard. This study presents a combination of semi-automatic method Double-Window Flexible Pace Search (DFPS) and edge detection technique to identify glacial lakes using Sentinel 2A satellite data. Initially, Normalized Difference Water Index (NDWI) has been used to identify water and non-water areas, while DFPS and Edge detection technique has been used to identify an optimum threshold value to distinguish between water and shadow areas. The optimal threshold from DFPS process is 0.21, while threshold value of gradient magnitude using edge detection process is 0.318. The number of glacial lakes identified using the above algorithm is in close agreement with previously published results on glacial lakes in Gangotri glacier using different techniques. Thus, a combination of DFPS and edge detection process has successfully segregated glacial lakes from other features present in Gangotri glacier. 相似文献
4.
近海水产养殖为人类提供优质的动物蛋白，对海洋经济高质量发展具有重要意义。卫星遥感技术已被广泛用于海岸带水产养殖的监测，但目前相关的研究聚焦基于单一传感器卫星数据并使用单一信息提取算法而忽略与不同卫星传感器以及处理方法之间的比较。本研究以北莉岛东北部为研究区，基于多光谱Sentinel 2A卫星和高分一号B（GF 1B）卫星数据，分别使用自适应阈值法、支持向量机监督分类法以及多尺度分割面向对象分类法，开展海岸带人工水产养殖区的识别。研究表明，更高空间分辨率的GF 1B卫星对人工水产养殖水网密集区的提取正确率远优于Sentinel 2A卫星；基于高空间分辨率GF 1B卫星，多尺度分割面向对象分类法的正确率最高，为94.65%，优于支持向量机监督分类法的94.45%和自适应阈值法的84.62%；自适应阈值法更适用于中等空间分辨率卫星数据的水产养殖信息提取，其提取的水产养殖水面的面积与目视解译提取的面积差异小于4%。针对单个养殖池使用情况的业务化监测需使用高空间分辨率卫星数据，而大范围水产养殖面积的变化分析则可应用中等空间分辨率卫星数据。 相似文献
5.
摘要：土壤水分是全球水循环的重要组成成分,对研究土壤水分的空间分布、农作物长势和产量 、气候变化、水资源时空分布等有着重要意义 。本文利用Sentinel（哨兵）系列主动微波雷达卫星SAR（Sentinel-1）结合光学卫星（Sentinel-2）对格尔木中下游低矮植被覆盖下的地表土壤水分进行反演研究, 探讨不同极化组合方式和水云模型前后的土壤水分含量反演方法的适用性。结果表明：其中VV (VV Polarization) 极化对比VH (VH Polarization) 极化更加适用该区域,VV极化结合归一化水指数 (NDWI）反演地表土壤水分精度达到42.6%,拟合精度最高,VH极化仅为22.6%;利用水云模型去除植被覆盖后对地表土壤水分的反演精度有所提升,其中,VV极化精度提高约3.5%,VH极化提高1.5%;Sentinel系列卫星影像对于干旱区的土壤水分的反演具有较好的适用性。本文旨在探索一种适用于该研究区乃至柴达木盆地土壤水分实现大面积实时监测的可靠依据和手段。 相似文献
6.
7.
DiDonato GT Stewart JR Sanger DM Robinson BJ Thompson BC Holland AF Van Dolah RF 《Marine pollution bulletin》2009,58(1):97-106
Population growth along the southeastern United States coast has precipitated the conversion of forested watersheds to suburban and urban ones. This study sampled creeks representing forested, suburban, and urban watersheds along a longitudinal gradient for indicators of water quality, including traditional indicator bacteria (fecal coliforms and enterococci) and alternative viral indicators (male-specific and somatic coliphages). Tested microorganisms were generally distributed with highest concentrations in creek headwaters and in more developed watersheds. The headwaters also showed the strongest predictive relationship between indicator concentrations and urbanization as measured by impervious cover. A seasonal pattern was observed for indicator bacteria but not for indicator viruses. Coliphage typing indicated the likely source of contamination was nonhuman. Results suggest that headwater creeks can serve as sentinel habitat, signaling early warning of public health concerns from land-based anthropogenic activities. This study also implies the potential to eventually forecast indicator concentrations under land use change scenarios. 相似文献
8.
Wesley Bissett Jr. Roger Smith Robert Field Tim Phillips Terry Wade James A. Thompson 《Marine pollution bulletin》2009,58(2):280-286
Locational risks for compromised ecosystem health for the eastern oysters (Crassostrea virginica) harvested from Lavaca Bay, Texas were estimated. Flow cytometric evaluation of variations in DNA content and the lysosomal destabilization assay were used for evaluation of genotoxicity and stress, respectively. Bayesian geo-statistical methods were utilized to estimate and evaluate spatial effects. For models with spatial risks, continuous surface maps of predicted parameter values were created to evaluate risk location. Lysosomal destabilization assay results were spatially oriented whereas flow cytometry results were fit best with the random effects model. While not spatially oriented, the highest levels of variations in DNA content were also present near industrial facilities. Locational risks of increased biomarkers of genotoxicity and stress in the eastern oyster (Crassostrea virginica) were increased with proximity to industrial facilities 相似文献
9.
Andrzej Chybicki 《Marine Geodesy》2018,41(1):1-23
Current trends of development of satellite derived bathymetry (SDB) models rely on applying calibration techniques including analytical approaches, neuro-fuzzy systems, regression optimization and others. In most of the cases, the SDB models are calibrated and verified for test sites, that provide favorable conditions for the remote derivation of bathymetry such as high water clarity, homogenous bottom type, low amount of sediment in the water and other factors. In this paper, a novel 3-dimensional geographical weighted regression (3GWR) SDB technique is presented, it binds together methods already presented in other studies, the geographically weighted local regression (GWR) model, with depth dependent inverse optimization. The proposed SDB model was calibrated and verified on a relatively difficult test site of the South Baltic near-shore areas with the use of multispectral observations acquired by a recently launched Sentinel-2 satellite observation system. By conducted experiments, it was shown that the proposed SDB model is capable of obtaining satisfactory results of RMSE ranging from 0.88 to 1.23[m] depending on the observation and can derive bathymetry for depths up to 12m. It was also shown, that the proposed approach may be used operationally, for instance, in the continuous assessment of temporal bathymetry changes, for areas important in the context of ensuring local maritime safety. 相似文献
10.
数据融合能够综合利用多源遥感数据优势,获取高空间分辨率和高测量精度的遥感影像,这对于近岸水体生态环境监测和灾害预警均具有重要意义。但目前使用的数据融合方法多是针对内陆水体或大洋水体的,其在近岸水体的适用性仍需进一步评估,因而本文开展了近岸水体遥感数据融合方法对比研究。本文以高空间分辨率的Sentinel-2 MSI影像和中等空间分辨率的Sentinel-3 OLCI影像为数据源,分别开展了基于小波变换（WTBF）、生物光学模型（BOBF）和混合像元分解（IUBF）三种方法的数据融合实验,并在此基础上借助现场实测Rrs数据与融合影像对应点的平均相对误差MRE、均方根误差RMSE、偏差bias和平均梯度对各种方法的融合数据质量和区域适用性进行了评估。结果表明：（1）OLCI的Rrs数据精度高于MSI。其中MSI在443 nm、560 nm和665 nm三个波段的MRE、RMSE均高于OLCI,表明MSI的Rrs精度相对OLCI较低;目视效果和平均梯度表明MSI的清晰度高于OLCI;（2）BOBF是三种方法中融合效果最佳的算法。WTBF和BOBF生成融合影像在三个波段的MRE、RMSE优于MSI。综合MRE、RMSE和bias来看,BOBF和WTBF所生成的影像Rrs准确性高于MSI,而IUBF生成的融合影像的MRE、RMSE和bias相对WTBF和BOBF较高,准确性较差;目视评价和平均梯度表征WTBF和BOBF生成影像的清晰度与MSI相近,BOBF清晰度高于WTBF,IUBF生成影像清晰度相对于OLCI有所提高但未达到MSI水平;（3）在Rrs更低的烟台近岸海域,BOBF生成的融合影像清晰度与MSI相当且Rrs准确性相对于MSI更高,BOBF在该海域具有良好的适用性。 相似文献