共查询到20条相似文献,搜索用时 15 毫秒
1.
A. Senthil Kumar T. Radhika P.K. Saritha V. Keerthi R. N. Anjani M. Suresh Kumar K. S. Sekhar P. Satyanarayana M. S. Naga Sudha M. V. R. Sesha Sai V. K. Dadhwal 《Journal of the Indian Society of Remote Sensing》2014,42(4):701-709
The use of Local Area Coverage (LAC) data from Ocean Color Monitor (OCM) sensor of Oceansat-2 with its high radiometric resolution (12 bits/pixel) and 2-day repeat cycle for rapid monitoring of vegetation growth and estimating surface albedo for the Indian region is demonstrated in this study. For the vegetation monitoring, normalized difference vegetation index (NDVI) and vegetation fraction (VF) products were estimated by maximum value composite approach fortnightly and were resampled to 1 km. The surface albedo products were realized by converting narrow-band eight-band spectral reflectance OCM data to a) visible (300–700 nm) and b) broad band (300–3,000 nm) data. For validation, the derived products were compared with respective MODIS global products and found to be in good agreement. 相似文献
2.
一种修正的星载散射计反演海面风场的场方式反演算法 总被引:11,自引:0,他引:11
由于卫星散射计探视雷达回波的各向异性的双调和性质,同时由于散向散射物理模型函数的非线性及信号中存在噪声,使得常规点方式风场反演哕向有多至4个解的多解存在。给出了一种改进的场方式钣演方法,利用该人卫星散射计测量的后向散射强度的数据中唯一反演出大尺度海洋风场。通过数值模拟和实际算例计算表明反演过程在风向、风速上都与真解是吻合的。从结果可以看到,所采用的改进的场方式反演方法对模拟数据或真实散射计探测海面 相似文献
3.
ERS散射计全球海面风场数据处理与ElNino海面风场异常观测 总被引:1,自引:0,他引:1
星载散射测量技术是获取全球海面风场的有效手段。该文研究了欧洲遥感卫星(ERS) 散射计全球海面风场数据的处理分析技术。对1997 年3 月、6 月和12 月的全球海面风场数据进行平均处理,并同时与1996 年6 月和1995 年10 月的观测数据进行对比,利用遥感技术发现了赤道太平洋西部的风场异常,从遥感资料上分析了1997 年El Nino 现象的海面风场( 风速与风向) 异常变化特征。研究结果显示了星载微波散射计在全球变化监测中的重要作用。 相似文献
4.
欧空局ERS1/2卫星上的风散射计(WSC),分辨率是50km,4天内能覆盖全球超过80%的范围,并可在多角度下对地物目标进行观测。本文研究利用该散射计数据估算土壤水分的方法。首先,利用基于ERS散射计数据建立的全球C波段雷达后向散射系数数据库,根据传统的几何光学模型(GOM),反演得到与土壤含水量密切相关的法线方向Fresnel反射率,并与两个采样点(安多和那曲)上的实测降雨量及土壤水分相对比,证明了ERS散射计数据与土壤水分的高相关性;第二步,以水云模型为基础,结合AIEM模型,发展了一种简化模型来估算土壤水分绝对值,分别利用气象站实测点数据和同时期的Basist湿度指数(BWI)进行验证,表明反演结果能较好反映土壤水分的空间分布状况。 相似文献
5.
Yan Gao Adrian Ghilardi Jaime Paneque-Galvez Margaret Skutsch Jean François Mas 《国际地球制图》2016,31(9):1019-1031
This study assesses whether MODIS Vegetation Continuous Fields percent tree cover (PTC) data can detect deforestation and forest degradation. To assess the usefulness of PTC for detecting deforestation, we used a data set consisting of eight forest and seven non-forest categories. To evaluate forest degradation, we used data from two temperate forest types in three conservation states: primary (dense), secondary (moderately degraded) and open (heavily degraded) forest. Our results show that PTC can differentiate temperate forest from non-forest categories (p = 0.05) and thus suggests PTC can adequately detect deforestation in temperate forests. In contrast, single-date PTC data does not appear to be adequate to detect forest degradation in temperate forests. As for tropical forest, PTC can partially discriminate between forest and non-forest categories. 相似文献
6.
Sandip R. Oza R. K. K. Singh N. K. Vyas Abhijit Sarkar 《Journal of the Indian Society of Remote Sensing》2010,38(4):611-616
Long term variations in Sea ice distribution strongly influence the atmosphere and ocean in the polar regions. In the recent
period significant variations in sea ice cover have been observed in both the hemispheres. In the past, studies have been
carried out that report the trends either at the Arctic/Antarctic level or at sector level. However, only a few studies have
concentrated on the investigation of trends at grid level using scatterometer data. The present study focuses on the investigations
of the sea ice trend at 1 × 1 degree grid level over the period 2000–2007 using QuickSCAT 0.2-degree resolution Scatterometer
data. It was observed that in the Arctic overall monthly trend is negative in all the sectors, with the Arctic level decline
of 3.26% per year. In the Antarctic, region-wise different trends have been observed. Negative trend is observed in the Amundsen-
Bellingshausen Seas and also in the Indian Ocean sector near the continental Ice shelves. It was highlighted that significant
trends exists within the pockets of marginal seas. 相似文献
7.
Gürcan Büyüksalih Güven Koçak Hüseyin Topan Murat Oruç Aycan Marangoz 《The Photogrammetric Record》2005,20(110):130-146
SPOT 5 HRG Level 1A and 1B stereo scenes covering Zonguldak testfield in north-west Turkey have been analysed. They comprise the left and right image components with base to height ratio of 0·54. The pixel size on the ground is 5 m. The bundle orientation was executed by the PCI Geomatica V9.1.4 software package and resulted in 3D geopositioning to sub-pixel accuracies in each axis provided that at least six control points were used in the computation. Root mean square error (rmse) values and vectors of residual errors for Levels 1A and 1B are similar, even for different control and check point configurations. Based on the scene orientation, Level 1A and 1B digital elevation models (DEMs) of the testfield have been determined by automatic matching and validated by the reference DEM digitised from the 1:25 000 scale topographic maps, interferometric DEMs from Shuttle Radar Topography Mission (SRTM) X- and C-band SAR data and the GPS profiles measured along the main roads in the testfield. Although the accuracies of reference data-sets are too similar to the generated SPOT DEMs, these are the only high quality reference materials available in this area. Sub-pixel height accuracy was indicated by the comparison with profile points. However, they are in favourable locations where matching is always successful, so such a result may give a biased measure of the accuracy of the corresponding DEMs. 相似文献
8.
9.
P. V. Nagamani M. I. Hussain S. B. Choudhury C. R. Panda P. Sanghamitra R. N. Kar A. Das I. V. Ramana K. H. Rao 《Journal of the Indian Society of Remote Sensing》2013,41(1):117-125
In this paper we report chlorophyll measurements made during an ocean colour validation cruise in April 2011 of the research vessel, Sagar Paschimi in the coastal waters of Northern Bay of Bengal. The chlorophyll-a concentration in these waters range from 0.2 to 4.0 mg/m3. Chlorophyll-a concentration from OCM-2 was estimated using the global ocean colour algorithms namely, OC2, OC3, OC4 and Chl-a algorithms respectively. OCM data was processed using the global SeaWiFS Data Analysis System (SeaDAS) in which all the above mentioned algorithms are embedded for estimating the chlorophyll-a concentration. A comparative study was made between and in-situ and satellite derived chlorophyll-a concentration. Although the matchups between in-situ and satellite data from OCM-2 were sparse, it indicates that direct application of the standard SeaWiFS algorithm-the OC4-V4 algorithm—in the coastal waters of the Bay of Bengal will underestimate chlorophyll-a by up to 30%. The results show a good correlation with an R value of 0.61 using OC2 algorithm. However, all the other global algorithms over estimate the chlorophyll-a concentration even in low chlorophyll concentration range. The comparison between in-situ and all the existing chlorophyll algorithms shows the efficiency of these algorithms for quantification of chlorophyll in coastal waters and hence the need to develop regional algorithms and fluorescence based algorithms for better quantification. 相似文献
10.
11.
Coastal Validation of Ultra-high Resolution Wind Vector Retrieval From QuikSCAT in the Gulf of Maine
《Geoscience and Remote Sensing Letters, IEEE》2009,6(3):413-417
12.
在中国地区部分无线电探空仪2003~2006年探空资料的基础上,对Bevis回归公式在中国地区的适用性进行了验证和分析。结果表明,利用Bevis回归公式得到的水汽加权平均温度Tm的精度与测站的海拔高度间存在着很强的线性关系。根据这种相关性,对其进行与高度相关的改进,改进后的回归公式可以应用于中国任何地区的水汽加权平均温度的计算。 相似文献
13.
针对SAR图像模拟方法进行了深入研究,提出了一种新的SAR图像模拟方法.该方法引入并改进信号模拟中经常使用的小面单元模型,并对SAR图像的阴影特征进行了分析;给出了一种高效判断阴影区域的算法.使用该方法对某一山地区域的DEM数据进行了SAR图像的模拟实验.实验结果表明:模拟的SAR图像和真实SAR图像纹理一致,很好地反映了起伏地区SAR图像的几何特征,取得了理想的效果. 相似文献
14.
针对SAR图像模拟方法进行了深入研究,提出了一种新的SAR图像模拟方法。该方法引入并改进信号模拟中经常使用的小面单元模型,并对SAR图像的阴影特征进行了分析;给出了一种高效判断阴影区域的算法。使用该方法对某一山地区域的DEM数据进行了SAR图像的模拟实验。实验结果表明:模拟的SAR图像和真实SAR图像纹理一致,很好地反映了起伏地区SAR图像的几何特征,取得了理想的效果。 相似文献
15.
Validation of Indian National DEM from Cartosat-1 Data 总被引:1,自引:0,他引:1
S. Muralikrishnan Abhijit Pillai B. Narender Shashivardhan Reddy V. Raghu Venkataraman V. K. Dadhwal 《Journal of the Indian Society of Remote Sensing》2013,41(1):1-13
CartoDEM is an Indian National DEM generated from Cartosat-1 stereo data. Cartosat-1, launched in May, 2005, is an along track (aft ?5°, Fore +26°) stereo with 2.5 m GSD, give base-height ratio of 0.63 with 27 km swath. The operational procedure of DEM generation comprises stereo strip triangulation of 500?×?27 km segment with 10 m posting along with 2.5 m resolution ortho image and free—access posting of 30 m has been made available (bhuvan.nrsc.gov.in). A multi approach evaluation of CartoDEM comprising (a) absolute accuracy with respect to ground control points for two sites namely Jagatsinghpur -flat and Dharamshala- hilly; second site i.e. Alwar-plain and hilly with high resolution aerial DEM, (b) relative difference between SRTM and ASTERDEM (c) absolute accuracy with ICESat GLAS for two sites namely Jagatsinghpur-plain and Netravathi river, Western Ghats-hilly (d) relative comparison of drainage delineation with respect to ASTERDEM is reported here. The absolute height accuracy in flat terrain was 4.7 m with horizontal accuracy of 7.3 m, while in hilly terrain it was 7 m height with a horizontal accuracy of 14 m. While comparison with ICESat GLAS data absolute height difference of plain and hilly was 5.2 m and 7.9 m respectively. When compared to SRTM over Indian landmass, 90 % of pixels reported were within ±8 m difference. The drainage delineation shows better accuracy and clear demarcation of catchment ridgeline and more reliable flow-path prediction in comparison with ASTER. The results qualify Indian DEM for using it operationally which is equivalent and better than the other publicly available DEMs like SRTM and ASTERDEM. 相似文献
16.
吴斌 《武汉大学学报(信息科学版)》2003,(Z1)
用高精度的现代日长观测结果、近 2 0年的J2 变化的结果和古地球自转结果 ,讨论了日长和J2 变化的长期和长周期的主要特性 ,从理论和实测两方面分析了日长和J2 变化的关系及其异同 ,认为J2 变化的结果在地球动力学研究中的作用应予以重视 ,综合利用日长和J2 将使这两种资料的潜力得以进一步发挥。 相似文献
17.
干旱半干旱沙尘爆发区风场信息作为沙尘监测的一个重要组成部分,能够为沙尘移向预报提供宝贵的资料。结合目前日趋成熟的红外分裂窗差值监测沙尘及卫星导风技术,针对FY-2E气象卫星,首先利用MODTRAN辐射传输模式对沙尘晴空区特征进行敏感性分析,再将经过图像掩膜及线性处理后的分裂窗差值图像代入导风计算程序计算,获得了传统卫星导风所无法得到的水汽含量低值区风场信息。实际个例分析表明,得到的沙尘区风场与NCEP再分析资料850hPa风场有很好的一致性,能够为监测沙尘移动提供良好的风场信息。 相似文献
18.
多时相MODIS影像水田信息提取研究 总被引:10,自引:0,他引:10
水稻种植及其分布信息是土地覆被变化、作物估产、甲烷排放、粮食安全和水资源管理分析的重要数据源。基于遥感的水田利用监测中,通常采用时序NDVI植被指数法和影像分类法分别进行AVHRR和TM影像的水田信息获取。针对8天合成MODIS陆地表面反射比数据的特点和水稻生长特征,选取水稻种植前的休耕期、秧苗移植期、秧苗生长期和成熟期等多时相MODIS地表反射率影像数据,通过归一化植被指数、增强植被指数及利用对土壤湿度和植被水分含量较敏感的短波红外波段计算得到的陆表水指数进行水田信息获取。将提取结果与基于ETM+影像的国土资源调查水田数据,通过网格化计算处理并进行对比分析,结果表明,利用MODIS影像的8天合成地表反射率数据,进行区域甚至全国的水田利用监测是可行的。 相似文献
19.
POLDER-2PARASOL卫星气溶胶业务产品在北京地区的验证分析 总被引:2,自引:1,他引:2
利用地面AERONET/PHOTONS气溶胶观测网北京和香河站点的资料,在北京地区对POLDER12/PARAsOL卫星多角度偏振信息获得的气溶胶反演产品进行了验证分析.地基AERONET/PHOTONS观测网的体积谱分布资料分析显示,在北京地区气溶胶尺度分布的细粒子截断半径约为0.3um.将POLDER-2/PARASOL卫星气溶胶业务产品和重新定义的地基AERONET/PHOTONs细模态(半径r<0.3p.m)气溶胶光学厚度(AOT)比较,两者在北京地区有着很好的一致性,说明卫星的气溶胶业务反演产品表征了主要来自人类污染排放的细粒子气溶胶贡献.然而,由于POLDER系列卫星业务反演方法固定了埃斯屈朗(Angstrom)指数的变化范围是1.8-3.0造成了细粒子贡献占绝对主导的局限.由地基AERONET/PHOTONS观测资料的分析可知,这个埃斯屈朗指数的先验值远远大于北京地区的地基测量结果,导致了POLDER业务反演的气溶胶光学厚度偏低,埃斯屈朗指数偏高. 相似文献
20.
阐述了建立独立坐标系的原因和原则,提出了建立独立坐标系的二重复合函数模型.该模型计算简单易于实现,符合建立独立坐标系的各项原则,能利用测区及其周围全部可靠高等级控制点作起算数据以提高控制网的精度,克服了现行一重函数模型的缺点. 相似文献