我国叶面积指数卫星遥感产品生产及验证

利用卫星遥感生产叶面积指数（Leaf area index： LAI）产品并进行真实性检验是植被定量遥感的一项重要研究内容。过去10 a,我国研究人员利用MODIS或AVHRR观测数据生产了GLOBALBNU, GLASS, GLOBMAP,MuSyQ和FSGOM等数套全球和全国LAI产品,受到了国内外的广泛关注和应用。在产品生产的同时,我国学者也广泛开展了LAI产品在全球和区域尺度的真实性检验研究工作。本文总结了我国LAI卫星产品生产和验证研究工作的现状和趋势。近年来,我国在本领域相关的理论、技术和方法研究方面取得了全面进展,LAI产品精度和连续性已与国外先进水平相当,但仍然存在数据源单一且依赖国外、算法不确定性不清、生产不连续以及缺乏充分验证等问题,客观上影响了LAI产品应用的广度及深度。未来应充分利用新的卫星数据特别是国产数据,加强遥感机理模型、反演算法以及应用的创新研究,生产具有特色的高质量LAI产品,满足地球系统科学的研究需求。同时,应加强LAI验证基础设施建设,发掘利用更广泛的验证站点,同时增进国际合作,加强产品的推广使用,在与用户的互动交流反馈中进一步提高产品的市场。随着我国对相关研究投入的增加,可以预期未来20 a将是我国LAI遥感产品及验证研究由“跟跑”国际先进水平向“并跑”乃至“领跑”过渡的机遇期。     

Accuracy assessment using sub-pixel fractional error matrices of global land cover products derived from satellite data

Information on land cover distribution at regional and global scales has become fundamental for studying global changes affecting ecological and climatic systems. The remote sensing community has responded to this increased interest by improving data quality and methodologies for extracting land cover information. However, in addition to the advantages provided by satellite products, certain limitations exist that need to be objectively quantified and clearly communicated to users so that they can make informed decisions on whether and how land cover products should be used. Accuracy assessment is the procedure used to quantify product quality. Some aspects of accuracy assessment for evaluating four global land cover maps over Canada are discussed in this paper. Attempts are made to quantify limiting factors resulting from the coarse spatial resolution of data used for generating land cover information at regional and global levels. Sub-pixel fractional error matrices are introduced as a more appropriate way for assessing the accuracy of mixed pixels. For classification with coarse spatial resolution data, limitations of the classification method produce a maximum achievable accuracy defined as the average percent fraction of dominant land cover of all pixels in the mapped area. Relationships among spatial resolution, landscape heterogeneity and thematic resolution were studied and reported. Other factors that can affect accuracy, such as misregistration and legend conversion, are also discussed.     

Comparison of country-level cropland areas between ESA-CCI land cover maps and FAOSTAT data

ABSTRACT

Long-term time series of spatially explicit cropland maps are essential for global crop modelling and climate change studies. The spatial resolution and temporal continuity of global cropland maps have been improving and several global data sets are released recently. Here, we calculated country-level cropland areas from the annual land-cover (LC) maps produced by the European Space Agency Climate Change Initiative (ESA-CCI) project and from the Food and Agricultural Organization of the United Nations statistical data (FAOSTAT) from 1992 to 2014. Because these two data sets used different approaches for generating the cropland data, we further quantified the consistency/difference in cropland areas and temporal changes between both products. Using log-transformed the time-averaged country-level cropland areas, a good linear relationship was found between these two products across different countries. However, only 8% of countries (mostly Organization for Economic Co-operation and Development countries) showed cropland area difference smaller than 1% between ESA-CCI and FAOSTAT. The cropland areas (without mosaic cropland types) from ESA-CCI are lower than the areas from FAOSTAT in 26% of countries but higher in 66% of countries. The magnitude of the latter difference (i.e. higher estimates of ESA-CCI than FAOSTAT) would be further amplified if crop intensity was taken into account. In addition, opposite temporal trends of cropland areas were found between these two data sets in 41% of countries. Although there are uncertainties in ESA-CCI LC maps, resulting from remote-sensing techniques such as mixed pixels, spectral similar objects, and same subject with different spectrum, the long time series and relatively high resolution of this product help us to understand the differences between satellite-based and inventory-based data sets and thus identify the possible strategies to improve the accuracy of satellite-based LC products.     

Google Earth as a virtual globe tool for Earth science applications at the global scale: progress and perspectives

Research on global environmental change requires new data processing and analysis tools that can integrate heterogeneous geospatial data from real-time in situ measurement, remote sensing (RS) and geographic information systems (GISs) at the global scale. The rapid growth of virtual globes for global geospatial information management and display holds promise to meet such a requirement. Virtual globes, Google Earth in particular, enable scientists around the world to communicate their data and research findings in an intuitive three-dimensional (3D) global perspective. Different from traditional GIS, virtual globes are low cost and easy to use in data collection, exploration and visualization. Since 2005, a considerable number of papers have been published in peer-reviewed journals and proceedings from a variety of disciplines. In this review, we examine the development and applications of Google Earth and highlight its merits and limitations for Earth science studies at the global scale. Most limitations are not unique to Google Earth, but to all virtual globe products. Several recent efforts to increase the functionalities in virtual globes for studies at the global scale are introduced. The power of virtual globes in their current generations is mostly restricted to functions as a ‘geobrowser’; a better virtual globe tool for Earth science and global environmental change studies is described.     

Lessons learned – Review of LCAs for ICT products and services

Application of information and communication technology (ICT) is often expected to result in decreased environmental impacts. Several studies have, however, also addressed the possibilities of negative impacts. It is therefore important to assess environmental impacts of ICT products and services. Life Cycle Assessment (LCA) is a tool for assessing the potential impacts of a product or service over the whole life-cycle, i.e. from raw material acquisition to waste management via production and use phases. The aim of this paper is to review LCA studies of ICT products and services, including a few Social Life Cycle Assessment (S-LCA) studies. Many of the studies have considered consumer products, such as computers and TVs. Other consumer products, such as game consoles and TV peripherals, as well as business products, e.g. related to networks, are however more rarely assessed. Manufacturing and use phase have the highest impact in the life cycle. Use phase seems to be the predominant in energy consumption and global warming for some ICT products but for others, especially energy efficient, low weight products, manufacturing may dominate. Rapid technological development is stressed by several authors as a source of variability of results, impacting the production processes and suppliers as well as the content and energy performance of the actual devices. In the future, conducting LCA on ICT, the research community needs to consider the limitations found in the studies conducted so far. It encompasses, among others, the need to address a broad spectrum of environmental impacts, including human and ecotoxicological impacts; modeling actual e-waste management, covering informal management when relevant; and considering user behavior in a realistic way, accounting for rebound and other indirect effects.     

Satellite data visualization system for education

It is important for environment protection to monitor changes in the environment by natural and human causes. It is also important to educate the next generation on the importance of the global environment issues. Recently, it has become possible to continually monitor the global environment using various satellite sensor data. But these satellite data are used for highly specialized analysis by experts in such fields, and the data cannot easily be used by non-experts. In this paper, we propose a satellite data visualization system for educational use. In the proposed system, a gray-scale 2-dimensional image is created from the satellite data. Next, a pseudo-color image is created from the gray-scale image to assist the comprehension of the data. A 3-dimensional data representation of the image is also created, to assist the comparison of the individual data. The aim of the created image is for educational use, and the image is created with emphasis on comprehension of the data, rather than presentation of data details. The aim of the proposed system is presenting the satellite data visually so that non-experts can easily understand. The target of this research is to apply the proposed system for natural science education and to improve the awareness of global environmental issues.     

Descriptive matrix factorization for sustainability Adopting the principle of opposites

Climate change, the global energy footprint, and strategies for sustainable development have become topics of considerable political and public interest. The public debate is informed by an exponentially growing amount of data and there are diverse partisan interest when it comes to interpretation. We therefore believe that data analysis methods are called for that provide results which are intuitively understandable even to non-experts. Moreover, such methods should be efficient so that non-experts users can perform their own analysis at low expense in order to understand the effects of different parameters and influential factors. In this paper, we discuss a new technique for factorizing data matrices that meets both these requirements. The basic idea is to represent a set of data by means of convex combinations of extreme data points. This often accommodates human cognition. In contrast to established factorization methods, the approach presented in this paper can also determine over-complete bases. At the same time, convex combinations allow for highly efficient matrix factorization. Based on techniques adopted from the field of distance geometry, we derive a linear time algorithm to determine suitable basis vectors for factorization. By means of the example of several environmental and developmental data sets we discuss the performance and characteristics of the proposed approach and validate that significant efficiency gains are obtainable without performance decreases compared to existing convexity constrained approaches.     

Validation and comparison of 1 km global land cover products in China

Four 1 km global land cover products are currently available to the scientific community: the University of Maryland (UMD) global land cover product, the International Geosphere–Biosphere Programme Data and Information System Cover (IGBP‐DISCover), the MODerate resolution Imaging Spectrometer (MODIS) global land cover product and Global Land Cover 2000 (GLC2000). Because of differences in data sources, temporal scales, classification systems and methodologies, it is important to compare and validate these global maps before using them for a variety of studies at regional to global scales. This study aimed to perform the validation and comparison of the four global land cover datasets, and to examine the suitability and accuracy of different coarse spatial resolution datasets in mapping and monitoring cropland across China. To meet this objective, we compared the four global land cover products with the National Land Cover Dataset 2000 (NLCD‐2000) at three scales to evaluate the accuracy of estimates of aggregated cropland areas in China. This was followed by a spatial comparison to assess the accuracies of the four products in estimating the spatial distribution of cropland across China. A comparative analysis showed that there are varying levels of apparent discrepancies in estimating the cropland of China between these four global land cover datasets, and that both area totals and spatial (dis)agreement between them vary from region to region. Among these, the MODIS dataset has the best fit in depicting China's croplands. The coarse spatial resolution and the per pixel classification approach, as well as landscape heterogeneity, are the main reasons for the large discrepancies between the global land cover datasets tested and the reference data.     

Shifts in sensory dominance between various stages of user-product interactions

In the area of product design, sensory dominance can be defined as the relative importance of different sensory modalities for product experience. It is often assumed that vision dominates the other senses. In the present study, we asked 243 participants to describe their experiences with consumer products in various situations: while buying a product, after the first week, the first month, and the first year of usage. The data suggest that the dominant sensory modality depends on the period of product usage. At the moment of buying, vision is the most important modality, but during the usage the other sensory modalities gain importance. The roles of the different modalities during usage are product-dependent. Averaged over 93 products analyzed in this study, after one month of usage touch becomes more important than vision, and after one year vision, touch and audition appear to be equally important. We conclude that to create a long-lasting positive product experience, designers need to consider user-product interaction at different stages of product usage and to determine which sensory modality dominates product experience at each stage.     

GLC2000: a new approach to global land cover mapping from Earth observation data

A new global land cover database for the year 2000 (GLC2000) has been produced by an international partnership of 30 research groups coordinated by the European Commission's Joint Research Centre. The database contains two levels of land cover information—detailed, regionally optimized land cover legends for each continent and a less thematically detailed global legend that harmonizes regional legends into one consistent product. The land cover maps are all based on daily data from the VEGETATION sensor on‐board SPOT 4, though mapping of some regions involved use of data from other Earth observing sensors to resolve specific issues. Detailed legend definition, image classification and map quality assurance were carried out region by region. The global product was made through aggregation of these. The database is designed to serve users from science programmes, policy makers, environmental convention secretariats, non‐governmental organizations and development‐aid projects. The regional and global data are available free of charge for all non‐commercial applications from http://www.gvm.jrc.it/glc2000.     

Fusion of EEG response and sentiment analysis of products review to predict customer satisfaction

This paper proposes a novel multimodal framework for rating prediction of consumer products by fusing different data sources, namely physiological signals, global reviews obtained separately for the product and its brand. The reviews posted by global viewers are retrieved and processed using Natural Language Processing (NLP) technique to compute compound score considered as global rating. Also, electroencephalogram (EEG) signals of the participants were recorded simultaneously while watching different products on computer’s screen. From EEG, valence scores in terms of product rating are obtained using self-report towards each viewed product for acquiring local rating. A higher valence score corresponds to intrinsic attractiveness of the participant towards a product. Random forest based regression techniques is used to model EEG data to build a rating prediction framework considered as local rating. Furthermore, Artificial Bee Colony (ABC) based optimization algorithm is used to boost the overall performance of the framework by fusing global and local ratings. EEG dataset of 40 participants including 25 male and 15 female is recorded while viewing 42 different products available on e-commerce website. Experiment results are encouraging and suggest that the proposed ABC optimization approach can achieve lower Root Mean Square Error (RMSE) in rating prediction as compared to individual unimodal schemes.     

Regionally adaptable dNBR-based algorithm for burned area mapping from MODIS data

Recent advances in instrument design have led to considerable improvements in wildfire mapping at regional and global scales. Global and regional active fire and burned area products are currently available from various satellite sensors. While only global products can provide consistent assessments of fire activity at the global, hemispherical or continental scales, the efficiency of their performance differs in various ecosystems. The available regional products are hard-coded to the specifics of a given ecosystem (e.g. boreal forest) and their mapping accuracy drops dramatically outside the intended area. We present a regionally adaptable semi-automated approach to mapping burned area using Moderate Resolution Imaging Spectroradiometer (MODIS) data. This is a flexible remote sensing/GIS-based algorithm which allows for easy modification of algorithm parameterization to adapt it to the regional specifics of fire occurrence in the biome or region of interest. The algorithm is based on Normalized Burned Ratio differencing (dNBR) and therefore retains the variability of spectral response of the area affected by fire and has the potential to be used beyond binary burned/unburned mapping for the first-order characterization of fire impacts from remotely sensed data. The algorithm inputs the MODIS Surface Reflectance 8-Day Composite product (MOD09A1) and the MODIS Active Fire product (MOD14) and outputs yearly maps of burned area with dNBR values and beginning and ending dates of mapping as the attributive information. Comparison of this product with high resolution burn scar information from Landsat ETM+ imagery and fire perimeter data shows high levels of accuracy in reporting burned area across different ecosystems. We evaluated algorithm performance in boreal forests of Central Siberia, Mediterranean-type ecosystems of California, and sagebrush steppe of the Great Basin region of the US. In each ecosystem the MODIS burned area estimates were within 15% of the estimates produced by the high resolution base with the R² between 0.87 and 0.99. In addition, the spatial accuracy of large burn scars in the boreal forests of Central Siberia was also high with Kappa values ranging between 0.76 and 0.79.     

AVHRR、VEGETATION和MODIS时间系列遥感数据产品现状与应用研究进展

全球时间系列卫星遥感产品自产生之日起就得到了高度关注,被广泛地应用于全球、洲际和区域的地表动态监测,并与气温、降水等气候变化表征参数结合起来,应用于全球变化分析。随着时间系列的逐渐延长和新兴传感器的不断涌现,时间系列遥感产品的内容和应用领域更是得到了极大扩展。主要介绍了:①当前国际上流行的可见光/近红外、短波红外和热红外时间系列卫星数据产品的发展现状,传感器主要包括AVHRR、VEGETATION和MODIS。早期以开发波段信息和植被指数等基础数据为主,当前大量专题产品的生产得到广泛开展;② 在数据产品的进一步处理和分析方面,重点介绍了时间系列重建、比较和延长、产品真实性检验的研究进展和发展趋势;③在数据产品应用方面,重点介绍了地表覆被特征的动态监测、物候和种植结构等信息提取、遥感产品在模型中的应用等方面的研究进展和发展趋势。     

Comparison of economic benefits of sensor embedded products and conventional products in a multi-product disassembly line

Sensors embedded into products during the production process are important data acquisition tools for after-sale products’ condition monitoring. By facilitating data collection from critical components in a product, these sensors help companies predict components and/or products failures during product usage. They are also very useful at the end-of-life (EOL) of products. Using sensor information, the conditions, types and remaining lives of components in an EOL product can be determined prior to actual disassembly. In this study, we assess the use of sensors in determining the steps in EOL processing of products. In particular, we evaluate the impact of sensor embedded products (SEPs) on various performance measures of an appliance disassembly line controlled by a multi-kanban system. First, separate design of experiments studies based on orthogonal arrays are carried out for conventional products (CPs) and SEPs. In order to calculate the response values for each experiment, detailed discrete event simulation models of both cases are developed considering the precedence relationships among the components together with the routing of different appliance types through the disassembly line. Then, pair-wise t-tests are conducted to compare the two cases based on different performance measures. The test results show the superiority of SEPs over CPs with respect to all costs (viz., disassembly, disposal, testing, backorder, transportation, holding) as well as revenue and profit.     

Temporal stability of some global NDVI products derived from NOAA/AVHRR GVI

The Normalized DilTerence Vegetation Index (NDVI) derived from NOAA's Advanced Very High Resolution Radiometer (AVHRR) has been widely used in monitoring continental and global vegetation distribution and dynamics, drought severity and location, and environmental deterioration. Since 1982, NOAA has produced the Weekly Global Vegetation Index (GVI) product from AVHRR. The analyses of the GVI product have revealed many problems due to the simplified radiometric correction involved in the processing. Those limitations have inspired several elTorts to reprocess the NOAA GVI data sets to produce an improved representation of global NDVI patterns. In this paper, the quality of three Global NDVI products resulting from very simple to rather sophisticated reprocessing was examined by using a global approach. In general, the quality of data improves with increasing sophistication of radiometric correction. However, this study reveals some significant errors common in all three products assessed. The problems include a systematic annual increase in values computed from a single satellite and jumps between consecutive satellites. These errors are large enough to alTect results of the long term time-series analyses. This pattern suggests an additional radiometric distortion in NOAA/ AVHRR data. It is found that the values computed from data of the first year after satellite launch are roughly the same statistically for NOAA satellites. Thus, the discontinuity ofNDVls between satellites appears to be mainly caused by the systematic drift. Therefore, data collected in the first year of satellite launch might be considered as a baseline for correcting the systematic errors. By comparing NDVI from the first year of satellites in space, it is also found that NDVI increases at higher latitude and decreases or keeps constant at lower latitude. This change of NDVI with time might signal the change of global climate.     

A comparative analysis of the Global Land Cover 2000 and MODIS land cover data sets

Accurate and up-to-date global land cover data sets are necessary for various global change research studies including climate change, biodiversity conservation, ecosystem assessment, and environmental modeling. In recent years, substantial advancement has been achieved in generating such data products. Yet, we are far from producing geospatially consistent high-quality data at an operational level. We compared the recently available Global Land Cover 2000 (GLC-2000) and MODerate resolution Imaging Spectrometer (MODIS) global land cover data to evaluate the similarities and differences in methodologies and results, and to identify areas of spatial agreement and disagreement. These two global land cover data sets were prepared using different data sources, classification systems, and methodologies, but using the same spatial resolution (i.e., 1 km) satellite data. Our analysis shows a general agreement at the class aggregate level except for savannas/shrublands, and wetlands. The disagreement, however, increases when comparing detailed land cover classes. Similarly, percent agreement between the two data sets was found to be highly variable among biomes. The identified areas of spatial agreement and disagreement will be useful for both data producers and users. Data producers may use the areas of spatial agreement for training area selection and pay special attention to areas of disagreement for further improvement in future land cover characterization and mapping. Users can conveniently use the findings in the areas of agreement, whereas users might need to verify the informaiton in the areas of disagreement with the help of secondary information. Learning from past experience and building on the existing infrastructure (e.g., regional networks), further research is necessary to (1) reduce ambiguity in land cover definitions, (2) increase availability of improved spatial, spectral, radiometric, and geometric resolution satellite data, and (3) develop advanced classification algorithms.     

全球日光诱导叶绿素荧光卫星遥感产品研究进展与展望

卫星反演的日光诱导叶绿素荧光（Solar-Induced chlorophyll Fluorescence, SIF）是全球植被生产力遥感监测的理想工具。现有的诸多大气成分探测卫星的高光谱载荷可以满足卫星平台SIF遥感探测的需求,中国和欧洲也计划发射专门的SIF卫星探测器。国内外学者生产了一系列全球SIF卫星遥感产品,并开展了SIF产品时空尺度扩展研究,为SIF应用研究提供了丰富的数据源,但现有的全球SIF产品仍然存在诸多局限性。系统梳理了现有和计划发射的SIF卫星载荷、目前公开发布的SIF卫星遥感产品、以及SIF时空尺度扩展产品,并从应用需求的角度出发,总结了现有全球SIF产品存在的问题和后续SIF卫星探测计划的发展方向,为现有SIF卫星产品的应用以及未来SIF探测卫星载荷方案的设计提供参考。     

全球环境变化视角下的土地覆盖分类系统研究综述

全球环境变化需要精确和最新的区域到全球尺度的土地覆盖数据集以支撑生态系统评估、生物多样性保护、气候变化研究和环境建模。然而,在土地覆盖分类数据集建立过程中,建立科学标准的分类系统至关重要,它影响着数据产品的集成与共享,数据的应用领域与范围。通过对区域尺度、全球尺度及可扩展的FAO土地覆盖分类系统进行评述,指出：① 目前国内外没有普遍认可并广泛应用的标准土地覆盖分类系统,这种分类系统的非标准化影响了数据产品的应用以及对土地覆盖变化的监测;② 复合特征是土地覆盖的固有属性,有效地表达与特征量化复合类型是需要不断努力去解决的问题;③ 我国迫切需要建立一套标准的土地覆盖分类系统,一方面能够与国际土地覆盖产品接轨,另一方面充分体现我国的自然环境特征。     

Simulation-based benchmarking of production control schemes for complex manufacturing systems

In this paper, benchmarking efforts for production control approaches applied to complex manufacturing systems are described. Complex manufacturing systems are characterized by a large number of products, an over time changing product mix, sequence-dependent set-up times, unrelated parallel machines, a mix of different process types, and internal and external disturbances. In order to ensure comparison possibilities among different production control approaches, the usage of a simulation test-bed and a software architecture that allows for plug in of different production control software are suggested. Different application areas, the advantages, and also the limitations of the suggested approach are discussed.     

Consumers' use of written product information

Two studies were conducted to investigate the predictive role of person-specific, product-specific, and situation-specific influences on the use of instruction manuals in the field of electrical consumer products. In a laboratory study, 42 participants were observed while putting a vacuum cleaner into operation. Situational primes (i.e., receiving a verbal cue that the packaging contains an instruction manual) increased the probability of the user manual being read. Additional verbal information that the manual contains information on energy-saving behaviours was especially motivating for persons with high environmental concern. Self-report data, collected on a wide range of products, suggest that product complexity is the best predictor of instruction manual use. In a second study with 30 participants, different positions of product labels were compared, i.e. placing the information on the packaging or directly onto the product. Information placed directly onto the product had a significantly higher influence on participants' actual behaviour than providing the same information on the packaging.