Atmospheric particulate matter (PM) estimation from SeaWiFS imagery

Air quality monitoring by satellite imagery is a potential complementary tool to in-situ measurements. Deriving particulate matter (PM) from the satellite derived aerosol optical thickness (AOT) is not straightforward. The relation between the two quantities is not explicit or, if so, too many unknowns exist. The idea, proposed by Pelletier et al. [Pelletier, B., Santer, R., & Vidot, J. (in press). Retrieving of particulate matter from optical measurements: A semiparametric approach. Journal of Geophysical Research, 112. doi:10.1029/2005JD006737], is to involve in the associations PM-AOT auxiliary meteorological information using a statistical approach. We use this method first on optical ground measurements and second on SeaWiFS imagery in the framework of a regional European project. A SeaWiFS archive was processed both over land and over ocean to produce AOT. A database was developed to associate locally and daily SeaWiFS AOT and PM. A part of this database was used to train the statistical method; another part of it was used for validation. Results are promising. Overall, the method allows retrieving the PM10 with a coefficient of determination of 0.42 and the PM2.5 with a coefficient of determination of 0.48. The outputs of this work are PM10 SeaWiFS maps and a limited comparison with in-situ data is reported.     

Satellite-based estimation of regional particulate matter (PM) in Beijing using vertical-and-RH correcting method

Theoretical analysis based on the atmospheric radiative transfer indicated a positive correlation between the aerosol optical thickness (AOT) and the surface-level particulate matter (PM) concentrations, and this correlation is improved significantly using vertical-and-RH correcting method. The correlative analysis of the ground-based measurement indicates that, (a) the correlation between AOT and the aerosol extinction coefficient at surface level (k_a,0) is improved as a result of the vertical correction, with the coefficient of determination R² increasing from 0.35 to 0.56; (b) the correlation between k_a,0 and PM concentrations can be significantly improved by the RH correction with the R² increasing from 0.43 to 0.77 for PM10, and from 0.35 to 0.66 for PM2.5. Based on the in-situ measurements in Beijing, two linear correlative models between the ground-based AOT and PMs (e.g. PM10 and PM2.5) concentrations were developed. These models are used to estimate the regional distribution of PM10 and PM2.5 using the satellite-retrieved AOT in Beijing area. Validation against the in-situ measurements in Beijing shows that both of the correlations of the satellite-estimated PM10 and PM2.5 with the measurements are R² = 0.47, and the biases are 26.33% and 6.49% respectively. When averaged in the urban area of Beijing, the R² between the estimated PM10 and the measurements increased to 0.66. These results suggest that by using the vertical-and-RH correcting method we can use the MODIS data to monitor the regional air pollution.     

Improved algorithm for MODIS satellite retrievals of aerosol optical thickness over land in dusty atmosphere: Implications for air quality monitoring in China

A new algorithm, using the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite reflectance and aerosol single scattering properties simulated from a chemistry transport model (GEOS-Chem), is developed to retrieve aerosol optical thickness (AOT) over land in China during the spring dust season. The algorithm first uses a “dynamic lower envelope” approach to sample the MODIS dark-pixel reflectance data in low AOT conditions, to derive the local surface visible (0.65 μm)/near infrared (NIR, 2.1 μm) reflectance ratio. Joint retrievals of AOT at 0.65 μm and surface reflectance at 2.1 μm are then performed, based on the time, location, and spectral-dependent single scattering properties of the dusty atmosphere as simulated by the GEOS-Chem. A linearized vector radiative transfer model (VLIDORT) that simultaneously computes the top-of-atmosphere reflectance and its Jacobian with respect to AOT, is used in the forward component of the inversion of MODIS reflectance to AOT. Comparison of retrieved AOT results in April and May of 2008 with AERONET observations shows a strong correlation (R = 0.83), with small bias (0.01), and small RMSE (0.17); the figures are a substantial improvement over corresponding values obtained with the MODIS Collection 5 AOT algorithm for the same study region and time period. The small bias is partially due to the consideration of dust effect at 2.1 μm channel, without which the bias is − 0.05. The surface PM₁₀ (particulate matter with diameter less than 10 μm) concentrations derived using this improved AOT retrieval show better agreement with ground observations than those derived from GEOS-Chem simulations alone, or those inferred from the MODIS Collection 5 AOT. This study underscores the value of using satellite reflectance to improve the air quality modeling and monitoring.     

上海市PM_(2.5)的时空分布特征及污染评估

首先选取2014年01-05月的上海市空气质量(AQI)日报,对首要污染物出现的频率做出统计分析,同时借助SPSS,绘制并分析全市日平均PM_(2.5)的时间分布图。然后根据上海市PM_(2.5)的10个监测站点2014年01月-04月的PM_(2.5)实时数据,对监测站点进行聚类分析,以发现各监测站点PM_(2.5)的空间分布特征。最后根据聚类结果,按照《环境空气质量标准》,对PM_(2.5)分区进行污染评估。研究表明,PM_(2.5)是上海市现阶段空气中的首要污染物;全市日平均PM_(2.5)浓度整体呈下降趋势;冬季PM_(2.5)污染程度整体明显高于春季;聚类结果第一类青浦淀山湖站属于一类区,其PM_(2.5)平均浓度远远超出一级环境空气污染物的浓度限值;第二三类属于二类区,其中浦东川沙站、浦东张江站PM_(2.5)平均浓度稍低于二级环境空气污染物的浓度限值,而其他监测站点则高出二级环境空气污染物的浓度限值。     

Modelling chain for the effect of road traffic on air and water quality: Techniques,current status and future prospects

Modelling approaches for simulating air and stormwater pollution due to on-road vehicles are reviewed and discussed. Models for traffic, emissions, atmospheric dispersion, and stormwater contamination are studied with particular emphasis on their couplings to create a modelling chain. The models must be carefully selected according to the requirements and level of detail of the integrated modelling chain. Although a fair amount of research has been conducted to link air pollution and road traffic, many questions related to spatio-temporal scales, domains of validity, consistency among models, uncertainties of model simulation results, and interfaces between models remain open. The aim of this work is to review the current status of the relationships between traffic, emissions, air quality, and water quality models, to recommend modelling approaches and to propose some directions for improving the state of the science. The difficulties and challenges associated with model coupling are illustrated with specific examples.     

Structuring the peer assessment process: a multilevel approach for the impact on product improvement and peer feedback quality

In order to optimize students' peer feedback processes, this study investigates how an instructional intervention in the peer assessment process can have a beneficial effect on students' performance in a wiki environment in first‐year higher education. The main aim was to study the effect of integrating a peer feedback template with a varying structuring degree. The present study involved three conditions: a no structure, a basic structure and an elaborate structure condition. Due to a clear hierarchical structure, in which over time (level 1), 168 students (level 2) are nested within 37 groups (level 3), multilevel analysis was performed to examine the effect of time, student and group level influences on students' peer feedback quality and product scores. The results revealed that both peer feedback quality and product scores increase significantly for all conditions over time, after multiple practice occasions. In addition, after several practice occasions, significant differences were found between the conditions in both peer feedback (elaborate higher than no structure) and product scores (elaborate and basic higher than no structure). Building on this, limitations, directions for future research and practical implications are presented.     

对应框架:欧洲与中国资格的一一对应(英文)

Both Ireland and the European Union use a framework of qualifications as a means of charting and describing the level of ability demonstrated by individuals in specific domains.Europe's frameworks are outcome based,identifying individuals by the level of ability they have demonstrated to assessors,and as such provide a useful means of mapping pathways through education for students,across a whole career or lifetime.Additionally,the framework serves as a communication tool,whereby institutions,students,employers or indeed countries can use a common vocabulary to discuss the achievements and abilities of individuals.We describe in brief the qualifications frameworks used in both China and Europe,and ask whether the European Qualifications Framework could serve as a communication tool between China and Europe.     

Defining assessment projects and scenarios for policy support: Use of ontology in Integrated Assessment and Modelling

Integrated Assessment and Modelling (IAM) provides an interdisciplinary approach to support ex-ante decision-making by combining quantitative models representing different systems and scales into a framework for integrated assessment. Scenarios in IAM are developed in the interaction between scientists and stakeholders to explore possible pathways of future development. As IAM typically combines models from different disciplines, there is a clear need for a consistent definition and implementation of scenarios across models, policy problems and scales. This paper presents such a unified conceptualization for scenario and assessment projects. We demonstrate the use of common ontologies in building this unified conceptualization, e.g. a common ontology on assessment projects and scenarios. The common ontology and the process of ontology engineering are used in a case study, which refers to the development of SEAMLESS-IF, an integrated modelling framework to assess agricultural and environmental policy options as to their contribution to sustainable development. The presented common ontology on assessment projects and scenarios can be reused by IAM consortia and if required, adapted by using the process of ontology engineering as proposed in this paper.     

Using background knowledge in case-based legal reasoning: A computational model and an intelligent learning environment

Researchers in the field of AI and Law have developed a number of computational models of the arguments that skilled attorneys make based on past cases. However, these models have not accounted for the ways that attorneys use middle-level normative background knowledge (1) to organize multi-case arguments, (2) to reason about the significance of differences between cases, and (3) to assess the relevance of precedent cases to a given problem situation. We present a novel model, that accounts for these argumentation phenomena. An evaluation study showed that arguments about the significance of distinctions based on this model help predict the outcome of cases in the area of trade secrets law, confirming the quality of these arguments. The model forms the basis of an intelligent learning environment called CATO, which was designed to help beginning law students acquire basic argumentation skills. CATO uses the model for a number of purposes, including the dynamic generation of argumentation examples. In a second evaluation study, carried out in the context of an actual legal writing course, we compared instruction with CATO against the best traditional legal writing instruction. The results indicate that CATO's example-based instructional approach is effective in teaching basic argumentation skills. However, a more “integrated” approach appears to be needed if students are to achieve better transfer of these skills to more complex contexts. CATO's argumentation model and instructional environment are a contribution to the research fields of AI and Law, Case-Based Reasoning, and AI and Education.     

Level of detail in UML models and its impact on model comprehension: A controlled experiment

Previous studies have shown that the style and rigor used in UML models vary widely across software projects [1], [2] and [3]. However, notwithstanding the varying use of styles and rigor, little research has been conducted to investigate the drivers and effects of using different styles and rigor in modeling on software development. In this paper, we evaluate Level of Detail (LoD) in UML models as a form of style and rigor in UML modeling. Using a UML model of a library system, we experimentally investigate the impact of LoD on model comprehension. More specifically, we explore whether LoD in UML models affects the correctness and efficiency in comprehending UML models. Using two independent groups of graduate students majoring in computer science, we performed a controlled experiment. The results of the experiment confirm the significant effect of LoD in UML models on model comprehension. Nevertheless, replication of this study is necessary, especially in contexts that involve professional software engineers, to improve the generalizability of the results.     

Behavioural effects of attitudes toward constraint in CASE: the impact of development task and project phase

This paper examines the effects of systems development task and phase upon individuals’ attitudes and behaviour while using computer‐aided systems engineering (CASE) tools. A previous empirical study of developers in several countries is revisited. Findings indicate that the mediating effects of task and phase upon the relationship among constraints, attitudes and behaviour are weak. They thereby support earlier research, which claims significance between attitudes and behaviour, by eliminating the potentially mediating effects of task and phase. Findings also indicate that CASE tool users associate implementation, integration and maintenance in terms of tasks and constraints, suggesting a reassessment of traditional life cycle models.     

Water supply sensitivity to climate change: An R package for implementing reservoir storage analysis in global and regional impact studies

Whilst there are numerous global and regional studies of climate impacts on water resources, relatively few authors have incorporated reservoir storage into their earth system models. Consequently, such studies are unlikely to provide coherent estimates of how changes in climate might affect water supplies globally. This short communication describes an R package, named reservoir, which has been designed for rapid and easy routing of runoff data through storage. The package comprises tools for capacity design, release policy optimisation and performance analysis—allowing users to specify realistic reservoirs and then assess performance in terms of meeting water delivery targets. We demonstrate some of the capabilities of reservoir using 271 runoff records from the Global Runoff Data Centre. The package is freely available through the Comprehensive R Archive Network (CRAN).     

Online ads in familiar and unfamiliar sites: effects on perceived website quality and intention to reuse

Electronic commerce is an integral part of most businesses today. The perceived quality of the website and whether users intend to reuse the site are of primary concern to online businesses. There are various factors that influence customers' intentions to reuse a site. In this paper, we investigate two of these factors: whether the site is familiar to the user and whether there are online advertisements on the website. The results indicate that familiarity and online ads do have an impact on quality and reuse, although it is not entirely as expected.     

Internet retransmissions in the real world: a comparative analysis of the legal and economic effects of over-the-top broadcast services in Singapore,the United States,and abroad

This paper analyzes the long-term impact of a case concerning an internet broadcast retransmission service called RecordTV from Singapore in comparison to the case of Aereo, where the Supreme Court found the broadcast live streaming service directly liable for copyright infringement. Scholars and industry professionals for and against Aereo predicted at different times that a ruling for the opposing side would undermine all local broadcasting, act as cloud computing’s death knell or would have some other adverse effect on broadcasting or innovation. By comparing the cases and their consequences, this paper aims to describe the unexpected real-world effects of permitting a third-party internet retransmission service to “free the airwaves.”     

Moderating effects of time pressure on the relationship between perceived value and purchase intention in social E-commerce sales promotion: Considering the impact of product involvement

How does customer perceived value influence purchase intention in online flash sales on social e-commerce platforms? This study investigates the role of time pressure and product involvement in the relationship between perceived value and purchase intention. Drawing on survey data from wjx.com in China, we found that perceived value is positively related to purchase intention, whereas time pressure negatively moderates the effect of emotional/social value on purchase intention. The three-way interaction among time pressure, perceived functional/emotional/social value, and product involvement was also statistically significant. We discuss the theoretical and practical implications of these results.     

Advancements in the design and validation of an air pollution integrated assessment model for Spain

This paper describes the design and application of the Atmospheric Evaluation and Research Integrated model for Spain (AERIS). Currently, AERIS can provide concentration profiles of NO₂, O₃, SO₂, NH₃, PM, as a response to emission variations of relevant sectors in Spain. Results are calculated using transfer matrices based on an air quality modelling system (AQMS) composed by the WRF (meteorology), SMOKE (emissions) and CMAQ (atmospheric-chemical processes) models. The AERIS outputs were statistically tested against the conventional AQMS and observations, revealing a good agreement in both cases. At the moment, integrated assessment in AERIS focuses only on the link between emissions and concentrations. The quantification of deposition, impacts (health, ecosystems) and costs will be introduced in the future. In conclusion, the main asset of AERIS is its accuracy in predicting air quality outcomes for different scenarios through a simple yet robust modelling framework, avoiding complex programming and long computing times.