检索结果-南通市图书馆

Estimating forest aboveground biomass using HJ-1.Satellite CCD and ICESat GLAS waveform data

Science china Earth Sciences 2010年第S1期53卷 16-25页

作者： GUO ZhiFeng1.CHI Hong1.2 & SUN GuoQing1.3.1.tate Key Laboratory of {1. sensing Science,Jointly Sponsored by the Institute of {1. sensing Applications of Chinese Academy of Sciences and Beijing Normal University,Institute of {1. sensing Applications,Chinese Academy of Sciences,Beijing 1.01.1.china 2Graduate University of Chinese Academy of Sciences,Beijing 1.0049,china 3.epartment of Geography University of Maryland,College Park,MD 20742,USA 1. State Key Laboratory of remote {1. Science Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University Institute of Remote Sensing Applications Chinese Academy of Sciences Beijing 100101 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. Department of Geography University of Maryland College Park MD 20742 USA

The ecosystem in northeastern china and the Russian Far East is a hotspot of scientific research into the global carbon *** aboveground biomass(AGB) is an important component in the land surface carbon *** this study,using forest inventory data and forest distribution data,the AGB was estimated for forest in Daxinganlin in northeastern china by combining charge-coupled device(CCD) data from the Small Satellite for Disaster and Environment Monitoring and Forecast(HJ-1. and Geoscience Laser Altimeter System(GLAS) waveform data from the Ice,Cloud and land Elevation Satellite(ICESat).The forest AGB prediction models were separately developed for different forest types in the research area at GLAS footprint level from GLAS waveform parameters and field survey plot biomass in the Changqing(CQ) Forest center,which was calculated from forest inventory *** resulted statistical regression models have a R2=0.68 for conifer and R2=0.71.for broadleaf *** models were used to estimate biomass for all GLAS footprints of forest located in the study *** GLAS footprint biomass coupled with various spectral reflectivity parameters and vegetation indices derived from HJ-1.satellite CCD data were used in multiple regression analyses to establish biomass prediction models(R2=0.55 and R2=0.52 for needle and broadleaf respectively).Then the models were used to produce a forest AGB map for the whole study area using the HJ-1.*** data obtained from forest inventory data of the Zhuanglin(ZL) Forest center were used as independent field measurements to validate the AGB estimated from HJ-1.CCD data(R2=0.71..About 80% of biomass samples had an error less than 20 t ha-1.and the mean error of all validation samples is 5.74 t *** pixel-level biomass map was then stratified into different biomass levels to illustrate the AGB spatial distribution pattern in this *** was found that HJ-1.wide-swath data and GLAS waveform data can be combined to estim

关键词： Disaster and Environment Monitoring and Forecast Satellite ICESat GLAS waveform boreal forest forest aboveground biomass multiple linear regression

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Simulating the impacts of climate variation and land-cover changes on basin hydrology: A case study of the Suomo basin

引用

Science china Earth Sciences 2005年第9期48卷 1501-1509页

作者： CHEN Junfeng1.2, LI Xiubin2 & ZHANG Ming2 1. Institute of remote {1. & GIS, Peking University, Beijing 1.0871. china 2. Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 1.01.1. china 1. Institute of remote {1. & GIS Peking University 100871 Beijing China 2. Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences 100101 Beijing Chin

Impacts of land cover changes on watershed hydrology have been a long-term academic concern with acute dispute. But little attention has been paid to such effects on mesoscale river basins, where the society has a closer link to river hydrology. The present study focuses on a mesoscale river basin, the Suomo Basin that is located on the upper reaches of the Yangtze River. Land covers in the basin in the years 1.70, 1.86 and 1.99 were mapped. A lumped hydrologic model, CHARM, and a distributed hydrologic model, SWAT, were used to model the impacts of both land-cover change and climate variation on river runoff during the past four decades. The results show that the contribution of climate variation to the change of runoff regime makes up 60%―80%, while that of land cover changes only 20%.

关键词： climate variation, land-cover changes, Suomo Basin, CHARM model, SWAT model.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Principle and application of three-band gradient difference vegetation index

引用

Science china Earth Sciences 2005年第2期48卷 241-249页

作者： TANG Shihao, ZHU Qijiang, WANG Jindi, ZHOU Yuyu & ZHAO Feng Research center for {1. sensing and GIS, Department of Geography, Beijing Normal University, Beijing 1.0875, {3. National Satellite Meteorological center, {3. Meteorological Administration, Beijing 1.0081. {3. 1. Research center for {1. sensing and GIS Department of Geography Beijing Normal University 100875 Beijing China 2. National Satellite Meteorological center China Meteorological Administration 100081 Beijing China

Vegetation index is a simple, effective and experiential measurement of terrestrial vegetation activity, and plays a very important role in qualitative and quantitative remote {1.. Aiming at shortages of current vegetation indices, and starting from the analysis of vegetation spectral characteristics, we put forward a new vegetation index, the three-band gradient difference vegetation index (TGDVI), and established algorithms to inverse crown cover fraction and leaf area index (LAI) from it. Theoretical analysis and model simulation show that TGDVI has high saturation point and the ability to remove the influence of background to some degree, and the explicit functional relation with crown cover fraction and LAI can be established. Moreover, study shows that TGDVI also has the ability to partly remove the influence of thin cloud. Experiment in the Shunyi District, Beijing, china shows that reasonable result can be reached using the vegetation index to retrieve LAI. We also theoretically analyzed the reason why the normalized difference vegetation index (NDVI) owns the low saturation point, and show that it is determined by the definition of NDVI and the characteristic of vegetation spectra, and is unavoidable to some degree. Meanwhile, through model simulation, we also indicate that the relationship between simple ratio vegetation index (SR) and LAI closes to a piecewise linear one instead of a linear one, which is mainly caused by the influence of background and different change rates of reflectance in red and infrared bands with LAI increasing.

关键词： vegetation index, remote sensing, LAI, crown cover fraction, remote sensing inversion.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Influence of mesoscale topography on vortex intensity

引用

Progress in Natural Science:Materials International 2008年第1期18卷 71-78页

作者： Zhexian Luo*,Yun Gao remote {1. College,Nanjing University of Information Science and Technology,Najing 21.044,china remote {1. College Nanjing University of Information Science and Technology Najing 210044 China

The effect of mesoscale topography on multi-vortex self-organization is investigated numerically in this paper using a barotropic prim- itive equation model with topographic *** the initial field there are one DeMaria major vortex with the maximum wind radius rm of 80 km at the center of the computational domain,and four meso-b vortices in the vicinity of rm to the east of the major vortex center. When there is no topography present,the initial vortices self-organize into a quasi-final state flow pattern,i.e.a quasi-axisymmetric vor- tex whose intensity is close to that of the initial major ***,when a mesoscale topography is incorporated,the spatial scale of the quasi-final state vortex reduces,and the relative vorticity at the center of the vortex and the local maximum wind speed remarkably *** possible mechanism for the enhancement of the quasi-final state vortex might be that the negative relative vorticity lump, generated above the mesoscale topography because of the constraint of absolute vorticity conservation,squeezes the center of positive vorticity towards the mountain slope area,and thus reduces the spatial range of the major ***,because the total kinetic energy is basically conservative,the squeezing directly leads to the concentration of the energy in a smaller area,*** strengthening of the vortex.

关键词： Mesoscale topography Vortex Self-organization Intensity change

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Study of coastal water zone ecosystem health in Zhejiang Province based on remote {1. data and GIS

引用

Acta Oceanologica Sinica 2010年第5期29卷 27-34页

作者： CHEN Zhenghua PAN Delu BAI Yan School of the Environment Gangxi University Nanning 530004 China State Environmental Protection Key Laboratory of Satellite remote {1. Ministry of Environmental Protection Institute of Remote Sensing Applications Chinese Academy of Sciences Beijing 100101 China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of Oceanography State Oceanic Administration Hangzhou 310012 China

The coastal ecosystem health assessment is a field of increasing *** this paper,a preliminary assessment of ecosystem health in Zhejiang coastal water zone was made,mainly based on remote {1. data and GIS *** spatial and quantitative evaluation was facilitated by the progress of remote {1. and GIS technique ***,human activities,hydrology and ecosystem problems in the study area were discussed and ***,from 4 aspects of human stress,physical,chemical and biological responses to anthropogenic activities and natural stress,several indicators such as water transparency（Secchi Disk Depth,SDD）,suspended substance concentration,dissolved inorganic nitrogen,active phosphate,chlorophyll,harmful algae bloom,as well as distribution of sewage,sea lanes and port were ***,the Analytic Hierarchical Process was used for indicator weight calculation,and the ecosystem health criteria were established according to the integrative analysis of national water quality criteria,similar coastal ecosystem health research in other places or data inherent *** results indicated that from 2005 to 2007 the coastal water ecosystem health value in Zhejiang Province was unhealthy and needs ecological restoration by human intervention.

关键词： coastal water zone ecosystem health indicator remote {1. GIS

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Probabilistic composition of cone-based cardinal direction relations

引用

Science china(Technological Sciences) 2008年第S1期51卷 81-90页

作者： LIU Yu1.TIAN Yuan1.& WENG JingNong2 1.Institute of remote {1. and Geographical Information Systems,Peking University,Beijing 1.0871.china 2 College of Software,Beihang University,Beijing 1.0083.china Peking Univ Inst Remote Sensing & Geog Informat Syst Beijing 100871 Peoples R China Beihang Univ Coll Software Beijing 100083 Peoples R China

Composition tables play a significant role in qualitative spatial reasoning (QSR). At present,a couple of composition tables focusing on various spatial relations have been developed in a qualitative approach. However,the spatial reasoning proc-esses are usually not purely qualitative in everyday life,where probability is one important issue that should be considered. In this paper,the probabilistic compo-sitions of cone-based cardinal direction relations (CDR) are discussed and esti-mated by making some assumptions. Consequently,the form of composition result turns to be {(R1.P1.,(R2,P2),…,(Rn,Pn)},where Pi is the probability associated with relation Ri. Employing the area integral method,the probabilities in each composi-tion case can be computed with the assumption that the target object is uniformly distributed in the corresponding cone regions.

关键词： spatial reasoning cardinal direction relations probabilistic composition

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Retrieving crop leaf area index by assimilation of MODIS data into a crop growth model

引用

Science china Earth Sciences 2010年第5期53卷 721-730页

作者： WANG DongWei1.2,3. WANG JinDi1.2 & LIANG ShunLin4 1.State Key Laboratory of {1. sensing Science, Jointly Sponsored by Beijing Normal University and Institute of {1. sensing Applications, CAS, Beijing 1.0875, china 2 School of Geography, Beijing Key Laboratory of Environmental {1. sensing and Digital City, Beijing Normal University, Beijing 1.0875, china 3.Haihe River Water Conservancy Commission, Tianjin 3.01.0, china 4 Department of Geography, University of Maryland, College Park, MD 20742, USA 1. State Key Laboratory of remote {1. Science Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing Applications CAS Beijing 100875 China2. School of Geography Beijing Key Laboratory of Environmental Remote Sensing and Digital City Beijing Normal University Beijing 100875 China3. Haihe River Water Conservancy Commission Tianjin 300170 China4. Department of Geography University of Maryland College Park MD 20742 USA

Leaf area index (LAI) is an important parameter in monitoring crop growth. One of the methods for retrieving LAI from remotely sensed observations is through inversion of canopy reflectance models. Many model inversion methods fail to account for variable LAI values at different crop growth stages. In this research, we use the crop growth model to describe the LAI changes with crop growth, and consider a priori LAI values at different crop growth stages as constraint information. The key approach of this research is to assimilate multiple canopy reflectance values observed at different growth stages and a priori LAI values into a coupled crop growth and radiative transfer model sequentially using a variational data assimilation algorithm. Adjoint method is used to minimize the cost function. Any other information source can be easily incorporated into the inversion cost function. The validation results show that the time series of MODIS canopy reflectance can greatly reduce the uncertainty of the inverted LAI values. Compared with MODIS LAI product at Changping and Shunyi Counties of Beijing, this method has significantly improved the estimated LAI temporal profile.

关键词： inversion leaf area index crop growth model time series MODIS

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Application of ensemble kalman filter to geophysical parameters retrieval in remote {1.:A case study of kernel-driven BRDF model inversion

引用

Science china Earth Sciences 2006年第6期49卷 632-640页

作者： QIN Jun1. YAN Guangjian1. LIU Shaomin1. LIANG Shunlin2, ZHANG Hao1. WANG Jindi1.& LI Xiaowen1.1. State Key Laboratory of remote {1. Science, School of Geography and remote {1., Research center for RS&GIS, Beijing Normal University, Beijing 1.0875, china 2. Department of Geography, 21.1.Lefrak Hall, University of Maryland, College Park, MD20742, USA 1. State Key Laboratory of remote {1. Science School of Geography and Remote Sensing Research Center for RS&GIS Beijing Normal University Beijing 100875 China 2. Department of Geography 2181 Lefrak Hall University of Maryland College Park MD20742 USA

The use of a priori knowledge in remote {1. inversion has great implications for ensuring the stability of inversion process and reducing uncertainties in retrieved results, especially under the condition of insufficient observations. Common optimization algorithms have difficulties in providing posterior distribution and thus cannot directly acquire uncertainties in inversion results, which is of no benefit to remote {1. application. In this article, ensemble Kalman filter (EnKF) has been introduced to retrieve surface geophysical parameters from remote {1. observations, which has the capability of not merely obtaining inversion results but also giving its posterior distribution. To show the advantage of EnKF, it is compared to standard MODIS AMBRALS algorithm and highly effi-cient global optimization method SCE-UA. The inversion abilities of kernel-driven BRDF models with different kernel combinations at several main cover types are emphatically discussed when observa-tions are deficient and a priori knowledge is introduced into inversion.

关键词： remote sensing inversion, a priori knowledge, posterior distribution, ensemble kalman filter, BRDF, kernel-driven model, albedo.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Improvement of a 3. radar backscattering model using matrix-doubling method

引用

Science china Earth Sciences 2010年第7期53卷 1029-1035页

作者： NI WenJian1.2, GUO ZhiFeng1.& SUN GuoQing3.1.State Key Laboratory of {1. sensing Science, jointly sponsored by the Institute of {1. sensing Applications of Chinese Academy of Sciences and Beijing Normal University, Beijing 1.01.1. china 2 Graduate University of Chinese Academy of Sciences, Beijing 1.0049, china 3.Department of Geography, University of Maryland, College Park, MD 27042, USA 1. State Key Laboratory of remote {1. Science jointly sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University Beijing 100101 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. Department of Geography University of Maryland College Park MD 27042 USA

Radiative transfer models have been widely used to simulate the radar backscattering from forested areas. A three-dimensional radar backscatter model of forest canopy developed in previous studies takes full account of spatial position of trees in a forest stand, and the interactions among crown, trunk and ground surface. The model predicted well for the co-polarized backscatter measurements, but underestimated the backscattering for cross-polarization, primarily because only the first-order scattering within tree crowns was considered in the model. The backscattering at cross-polarization depends strongly on multiple scatter- ing within tree crowns. To produce good estimations for cross-polarized component, the matrix-doubling method is employed here to compute multiple-scattering within the crown. The modified model is compared with the original model, and the field forest measurements and AIRSAR data are used for validation of the modified model. The cross-polarization backscattering is improved in different degrees for different crown structures and at different bands.

关键词： remote sensing forestry electromagnetic propagation radar backscattering model matrix-doubling

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Topological relations between directed lines and simple geometries

引用

Science china(Technological Sciences) 2008年第S1期51卷 91-101页

作者： GAO Yong1.ZHANG Yi1.TIAN Yuan1.& WENG JingNong2 1.Institute of remote {1. and Geographic Information System,Peking University,Beijing 1.0871.china 2 Colledge of Software,Beihang University,Beijing 1.0083.china 1. Institute of remote {1. and Geographic Information System Peking University Beijing 100871 China2. Colledge of Software Beihang University Beijing 100083 China

Directed lines are fundamental geometric elements to represent directed linear en-tities. The representations of their topological relations are so different from those of simple lines that they cannot be solved exactly with normal methods. In this paper,a new model based on point-set topology is defined to represent the topo-logical relations between directed lines and simple geometries. Through the inter-sections between the start-points,end-points,and interiors of the directed lines and the interiors,boundaries,and exteriors of the simple geometries,this model identifies 5 cases of topological relations between directed lines and points,3. cases of simple lines,and 26 cases of simple polygons. Another 4 cases of simple lines and one case of simple polygons are distinguished if considering the exteri-ors of the directed lines. All possible cases are furthermore grouped into an exclu-sive and complete set containing 1. named predicts. And the conceptual neigh-borhood graph is set up to illustrate their relationship and similarity. This model can provide a basis for natural language description and spatial query language to present the dynamic semantics of directed lines relative to the background fea-tures.

关键词： topological relation directed line simple geometry intersection model

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：