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Space- and ground-based CO_2 measurements： A review

Science China Earth Sciences 2016年第11期59卷 2089-2097页

作者： YUE TianXiang ZHANG LiLi ZHAO MingWei WANG YiFu John WILSON State Key Laboratory of Resources and Environment information System Institute of Geographical Science and Natural Resources Research Beijing 100101 China Jiangsu Center for Collaborative Innovation in geographical information Resource Development and Application Nanjing 210046 China Anhui Center for Collaborative Innovation in geographical information Integration and Application Chuzhou University Chuzhou 239012 China spatial Sciences institute University of Southern California Los Angles CA90089-0374 USA

The climate warming is mainly due to the increase in concentrations of anthropogenic greenhouse gases, of which CO_2 is the most important one responsible for radiative forcing of the climate. In order to reduce the great estimation uncertainty of atmospheric CO_2 concentrations, several CO_2-related satellites have been successfully launched and many future greenhouse gas monitoring missions are planned. In this paper, we review the development of CO_2 retrieval algorithms, spatial interpolation methods and ground observations. The main findings include: 1) current CO_2 retrieval algorithms only partially account for atmospheric scattering effects; 2) the accurate estimation of the vertical profile of greenhouse gas concentrations is a long-term challenge for remote sensing techniques; 3) ground-based observations are too sparse to accurately infer CO_2 concentrations on regional scales; and 4) accuracy is the primary challenge of satellite estimation of CO_2 concentrations. These findings, taken as a whole, point to the need to develop a high accuracy method for simulation of carbon sources and sinks on the basis of the fundamental theorem of Earth's surface modelling, which is able to efficiently fuse space- and ground-based measurements on the one hand and work with atmospheric transport models on the other hand.

关键词： Accuracy Carbon satellites Retrieval algorithms Space-and ground-based measurements HASM

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Integration of InSAR and GPS for hydraulic engineering

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Science China(Technological Sciences) 2007年第z1期50卷 111-124页

作者： HE XiuFeng LUO HaiBin HUANG QiHuan HE Min institute of Satellite Navigation & spatial information System Hohai UniversityNanjing 210098China Institute of Satellite Navigation & Spatial Information SystemHohai UniversityNanjing 210098China Institute of Satellite Navigation & Spatial Information SystemHohai UniversityNanjing 210098China Institute of Satellite Navigation & Spatial Information SystemHohai UniversityNanjing 210098China

Interferometric synthetic aperture radar (InSAR) is a potential earth observation approach, and it has been demonstrated to have a variety of applications in measuring ground movement, urban subsidence and landslides. Currently InSAR provides the ability to map accurate DEM and measure ground deformation to sub-centimeter accuracy. However, many factors affect InSAR to measure ground movement since dam constructions are built in a large scale area with a complicated climate and unstable geology. This paper discusses potential applications of integrated InSAR and GPS to monitor a large-scale ground movement due to hydropower developments. The integration of InSAR and GPS can provide a cost-effective means for monitoring deformation of hydropower developments. Moreover, two novel methods, both the improved spatial interpolating method and estimation of 3D surface motion velocities method, are proposed and the experimental results and analysis are given in this paper.

关键词： InSAR GPS hydraulic and hydropower engineering slides monitoring

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Tracking the Moisture Sources of an Extreme Precipitation Event in Shandong,China in July 2007:A Computational Analysis

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Journal of Meteorological Research 2014年第4期28卷 634-644页

作者：张弛李琦 institute of Remote Sensing and geographical information Systems Peking University

This paper utilizes a modified Water Accounting Model （WAM） to track the moisture sources of an extreme precipitation event in Shandong during 18-20 July 2007. It is found that different methods in dealing with the residual of the water budget always produce different results in moisture recycling calculations. In addition, results from the backward tracking without the residual are in complete agreement with those from the forward tracking with the residual, and vice versa, implying a mathematical consistency. We thus analyze and derive the conditions under which the two tracking approaches equate with each other. We applied the backward tracking to the Shandong extreme rainfall case and obtained quantitative estimates of moisture contributions of three selected regions away from the rainfall area. The results indicate that the spatial pattern rather than numerical value of the recycling moisture is more reliable in tracking the moisture sources. The moisture of this Shandong rainfall event comes mostly from the nearby upwind area in Southwest China, which is of the terrestrial origin; while the moisture originating from the neighboring West Pacific contributes little to this event.

关键词： bulk model precipitation recycling moisture recycling backward tracking

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Optimizing segmented trajectory data storage with HBase for improved spatio-temporal query efficiency

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International Journal of Digital Earth 2023年第1期16卷 1124-1143页

作者： Yi Bao Zhou Huang Xuri Gong Yuyang Zhang Ganmin Yin Han Wang institute of Remote Sensing and geographical information Systems Peking UniversityBeiingPeople's Republic of China Beijing Key Lab of spatial information Integration&Its Applications Peking UniversityBejjingPeople's Republic of China

The surging accumulation of trajectory data has yielded invaluable insights into urban systems,but it has also presented challenges for data storage and management *** response,specialized storage systems based on non-relational databases have been developed to support large data quantities in distributed ***,these systems often utilize storage by point or storage by trajectory methods,both of which have *** this study,we evaluate the effectiveness of segmented trajectory data storage with HBase optimizations for spatio-temporal *** develop a prototype system that includes trajectory segmentation,serialization,and spatio-temporal indexing and apply it to taxi trajectory data in *** indicate that the segmented system provides enhanced query speed and reduced memory usage compared to the Geomesa system.

关键词： Trajectory storage HBase trajectory segmentation spatio-temporal query

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Progress and performance evaluation of Bei Dou global navigation satellite system： Data analysis based on BDS-3 demonstration system

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Science China Earth Sciences 2018年第5期61卷 614-624页

作者： Yuanxi YANG Yangyin XU Jinlong LI Cheng YANG State Key Laboratory of Geo-information Engineering Xi'an 710054 China institute of geographical spatial information Information Engineering University Zhengzhou 450001 China Beijing Satellite Navigation Center Beijing 100094 China School of Land Science and Geomatics China University of Geosciences Beijing 100083 China

The first two Medium Earth Orbit(MEO) satellites of the third generation of Bei Dou satellite navigation System(BDS-3) were successfully launched on November 5, 2017. This historical launch starts the new era of the global navigation satellite system of Bei Dou. Before the first two satellites of BDS-3, a demonstration system for BDS-3 with five satellites,including two Inclined Geosynchronous Orbit satellites(IGSO) and three MEO satellites, was established between 2015 and2016 for testing the new payloads, new designed signals and new techniques. In the demonstration system, the new S frequency signal and satellite hydrogen clock as well as inter-satellite link(ISL) based on Ka-band signals with time-division multiple addresses(TDMA) were tested. This paper mainly analyzes the performances of the demonstration system, including the signalto-noise ratios, pseudorange errors and the multipath errors of the civilian signals of BDS-3. The qualities of signals in space,time synchronization and timing precision were tested as well. Most of the performances were compared with those of the regional Bei Dou satellite navigation system(BDS-2). At last, the performances of positioning, navigation and timing(PNT) of the future Bei Dou global system(BDS-3) were evaluated based on the signal quality of the present demonstration satellite system.

关键词： Bei Dou-3 Demonstration satellite Signal Timing Signal-to-noise ratios

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An ensemble learning simplification approach based on multiple machine-learning algorithms with the fusion using of raster and vector data and a use case of coastline simplification

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Cehui Xuebao/Acta Geodaetica et Cartographica Sinica 2022年第3期51卷 373-387页

作者： Du, Jiawei Wu, Fang Zhu, Li Liu, Chengyi Wang, Andong institute of geographical spatial information Information Engineering University Zhengzhou 450001 China

To make use of accumulated simplification data and their contained simplification knowledge sufficiently, we propose an intelligent method based on the integration of several machine learning algorithms, which can use vector features and raster images to learn the vertex selection of polyline simplification in this paper. First, vertex selection models based on vector features and raster images are constructed by the fully connected neural network and the convolutional neural network respectively. Trained by corresponding samples, these two models can be utilized to generate vertex selection decisions via inputting vector features or raster images respectively. Second, some fusion models are constructed based on the linear weighting method, naive Bayes method, support vector machine, and artificial neural network to utilize outputs of vector-based and raster-based models to generate better decisions for vertex simplification. Finally, the proposed method applies into a use case. Experimental results show that the vector-based model and the raster-based model can learn and master vertex simplification in different levels, and fusion models can make complementary advantages of raster-based and vector-based models to improve the simplification accuracy further, and the best fusion model is better than some other simplification methods. © 2022, Surveying and Mapping Press. All right reserved.

关键词： Vectors

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Characteristics of permafrost degradation in Northeast China and its ecological effects: A review

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Research in Cold and Arid Regions 2020年第1期12卷 1-11页

作者： ShanShan Chen ShuYing Zang Li Sun Heilongjiang Province Key Laboratory of geographical Environment Monitoring and spatial information Service in Cold Regions Harbin Normal University

Latitudinal permafrost in Northern Northeast(NNE)China is located in the southern margin of the Eurasian continent,and is very sensitive to climatic and environmental *** simulations indicate that air temperature in the permafrost regions of Northeast China has been on the rise since the 1950s,and will keep rising in the 21st century,leading to extensive degradation of *** degradation in NNE China has its own characteristics,such as northward shifts in the shape of a"W"for the permafrost southern boundary(SLP),discontinuous permafrost degradation into islandlike frozen soil,and gradually disappearing island *** degradation leads to deterioration of the ecological environment in cold *** a result,the belt of larch forests dominated by Larix gmelinii has shifted northwards and wetland areas with symbiotic relationships with permafrost have decreased *** rapid retreat and thinning of permafrost and vegetation change,the CO2 and CH4 flux increases with mean air temperature from continuous to sporadic permafrost areas as a result of activity of methanogen enhancement,positively feeding back to climate *** paper reviews the features of permafrost degradation,the effects of permafrost degradation on wetland and forest ecosystem structure and function,and greenhouse gas emissions on latitudinal permafrost in NNE *** also put forward critical questions about the aforementioned effects,including:(1)establish long-term permafrost observation systems to evaluate the distribution of permafrost and SLP change,in order to study the feedback of permafrost to climate change;(2)carry out research about the effects of permafrost degradation on the wetland ecosystem and the response of Xing'an larch to global change,and predict ecosystem dynamics in permafrost degradation based on long-term field observation;(3)focus intensively on the dynamics of greenhouse gas flux in permafrost degradation of Northe

关键词： climate warming permafrost degradation greenhouse gas emissions ecosystem impact

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A simple data assimilation method for improving the MODIS LAI time-series data products based on the object analysis and gradient inverse weighted filter

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Chinese Optics Letters 2007年第6期5卷 367-369页

作者：何彬彬 institute of Geo-spatial information Science and Technology University of Electronic Science and Technology of China

A simple data assimilation method for improving estimation of moderate resolution imaging spectroradiometer （MODIS） leaf area index （LAI） time-series data products based on the gradient inverse weighted filter and object analysis is proposed. The properties and quality control （QC） of MODIS LAI data products are introduced. Also, the gradient inverse weighted filter and object analysis are analyzed. An experiment based on the simple data assimilation method is performed using MODIS LAI data sets from 2000 to 2005 of Guizhou Province in China.

关键词： MODIS data A simple data assimilation method for improving the MODIS LAI time-series data products based on the object analysis and gradient inverse weighted filter LAI time

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A Pan-sharpening method appropriate to vegetation applications

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Chinese Optics Letters 2009年第9期7卷 781-783页

作者：张瑛何彬彬李小文 institute of Geo-spatial information Science and Technology University of Electronic Science Technology of China

An improved Pan-sharpening algorithm appropriate to vegetation applications is proposed to fuse a set of IKONOS panchromatic （PAN） and multispectral image （MSI） data. The normalized difference vegetation index （NDVI） is introduced to evaluate the quality of fusion products. Compared with other methods such as principal component analysis （PCA）, wavelet transform （WT）, and curvelet transform （CT）, this algorithm has a better trade-off between keeping the spatial and spectral information. The NDVI performances indicate that the fusion product of this method is more suitable for vegetation applications than the other methods.

关键词： Conductive plastics Principal component analysis Quality control Wavelet transforms

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Research on Ubiquitous Map information Organization Oriented to Location-Based Aggregation

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Journal of Geoscience and Environment Protection 2022年第1期10卷 238-249页

作者： Si Wang Guangxia Wang institute of geographical spatial information Information Engineering University Zhengzhou China

In the era of information and communication technology (ICT) and big data, the map gradually shows a new qualitative feature of “spatiotemporal ubiquitous” due to the extension of its object space and the geographic information it contains, which brings new challenges to map information organization. This paper analyzes the concept and information characteristics of the ubiquitous map. Based on that, it proposes a ubiquitous map information organization model oriented to location-based aggregation. This new model includes three parts as “ubiquitous map instance”, “location-based aggregation mode” and “map scene”. This paper focuses on the “map scene” part which is the core of the model and contains two mutually mapped aspects as “content scene” and “representation scene”. And both aspects are divided into three levels as “features” ←→ “elements” ←→ “scenes” according to ubiquitous map information characteristics and location-based aggregation mode. With cases of map decomposition, the application of the model is explained to illustrate its effectiveness. The model is expected to provide powerful data organization and management capabilities for ubiquitous map production and use.

关键词： Ubiquitous Map information Organization Location-Based Aggregation Map Scene

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