bluuebunny/crossref_metadata_2025 huggingface dataset:
Agent-Based Distributed Intelligent Tutoring System Using Case-Based Reasoning
Authors: Shweta  , Dhyani Praveen , Rishi O. P.
Published: September 2014

Intelligent Tutoring Systems have proven their worth in multiple ways and in multiple domains in education. In this chapter, the proposed Agent-Based Distributed ITS using CBR for enhancing the intelligent learning environment is introduced. The general architecture of the ABDITS is formed by the three components that generally characterize an ITS: the Student Model, the Domain Model, and the Pedagogical Model. In addition, a Tutor Model has been added to the ITS, which provides the functionality that the teacher of the system needs. Pedagogical strategies are stored in cases, each dictating, given a specific situation, which tutoring action to make next. Reinforcement learning is used to improve various aspects of the CBR module: cases are learned and retrieval and adaptation are improved, thus modifying the pedagogical strategies based on empirical feedback on each tutoring session. The student modeling is a core component in the development of proposed ITS. In this chapter, the authors describe how a Multi-Agent Intelligent system can provide effective learning using Case-Based Student Modeling.
Evaluation of Clustering Methods for Adaptive Learning Systems
Authors: Hämäläinen Wilhelmiina , Kumpulainen Ville , Mozgovoy Maxim
Published: September 2014

Clustering student data is a central task in the educational data mining and design of intelligent learning tools. The problem is that there are thousands of clustering algorithms but no general guidelines about which method to choose. The optimal choice is of course problem- and data-dependent and can seldom be found without trying several methods. Still, the purposes of clustering students and the typical features of educational data make certain clustering methods more suitable or attractive. In this chapter, the authors evaluate the main clustering methods from this perspective. Based on the analysis, the authors suggest the most promising clustering methods for different situations.
Serving Nontraditional Students
Authors: Newman Dianna L. , Deyoe Meghan Morris , Seelow David
Published: September 2014

The role of technology and educational media in supporting nontraditional adult learners is growing. One key area in which more research and development is needed is the improvement of writing, especially writing that is related to formal education. This chapter presents findings related to the use of online writing modules developed to support English as a Second Language and nontraditional English speaking college students. Participants reported improved content-specific writing skills, transfer of writing skills to other content areas, and increased self-efficacy in writing. Differences continued to be noted by key student characteristics. The study has implications for continued development and use of digitally supported writing tutorials for nontraditional adult learners.
Blending in the Humanities
Authors: Klocke Astrid , Hedegard Danielle
Published: September 2014

Does technology de-place opportunities for meaningful engagement? Is the reduction of face-to-face time in a blended course a loss to students? And if so, what students are most affected by this shift? Can a blended course only work in disciplines that rely on teaching “facts” or can the recent emergence of digital humanities serve as a framework and provide disciplinary-specific insights for the use of teaching technology in the humanities? This chapter explores the use of learning technology and blended design in an introductory humanities course. Further, the chapter presents a blended course model, assessment data, and ideas for contextual reflection about how change in higher education paradigms is affecting the humanities in order to address them in a cooperative, non-disruptive way. Finally, the unique context, assumptions, and causes for resistance to change in the humanities with regard to technology and blended pedagogy are discussed. This chapter is intended to help readers anticipate and address particular disciplinary perceptions of blended learning.
A Model for Improving Online Collaborative Learning through Machine Learning
Authors: Maina E. Muuro , Wagacha Peter W. , Oboko Robert O.
Published: September 2014

Online collaborative learning provides new opportunities for student collaboration in an online learning environment and at the same time spawns new challenges for teachers supporting group work. With the current Course Management Systems (CMS) such as Moodle, technology has provided online tools that include discussions forums, chat rooms, e-mails, newsgroups, workshops, etc. These tools provide a collaborative learning environment. To include constructivist learning in an online learning environment is a good collaborative strategy that is necessary since it engages learners in learning activities through interaction with their peers and teacher. A good collaborative strategy in an e-learning environment must primarily ensure that the expected interaction occurs in line with the learning mechanism being employed. This cannot merely be met by offering a set of collaborative software tools alone. It also requires the instructors' support. As the number of students studying online continues to increase, there is need to develop models that can improve online collaborative learning with minimal involvement of the instructor because the instructor might not be able to cope with increased number of students. To address this need, this chapter discusses a novel model for improving online collaborative learning that uses Machine Learning (ML) techniques.
Using Technology to Enhance Teacher Preparation Field Experiences
Authors: Thomas Ursula
Published: September 2014

This chapter describes a field director's revision of a field experience placement system and model for a teacher education program at a two-year institution. In this case study, the field director documented the conversion from a paper system to using a learning management system to support the field experience process of 324 students. Results from this case study indicate a positive correlation between the components of the process and the features of the learning management system. In addition, findings from the case study reveal that the learning management system provides additional benefits for program assessment. The conversion of a paper system to a learning management system is documented as well as the implications for other aspects of teacher education assessment.
Improving the Work Integrated Learning Experience through Mobile Technologies
Authors: Dann Chris , Richardson Tony
Published: September 2014

The inclusion of technological solutions in higher education has led to a vast array of options for educators. An educational problem has driven each solution and the associated research into defining the effectiveness of those solutions. This chapter describes some of the problems faced by a teacher education program, triggered by the use of Work Integrated Learning (WIL), to connect theory taught in universities to the realities of a teacher's life. The underlying beliefs of the authors are that there needs to be critical discourse about the teaching and learning models used to engage students in the art of workplace learning, that this critical discourse needs to be based on facilitating a teaching and learning environment that is highly effective, and that the nexus is that the student's Work Integrated Learning (WIL) experience will not be counterproductive. This chapter highlights a concrete example of how one university implemented these beliefs in a structured and proactive manner.
Using Mobile Technologies to Co-Construct TPACK in Teacher Education
Authors: de Groot Cornelis , Fogleman Jay , Kern Diane
Published: September 2014

How student teachers might benefit from using their mobile technologies during teaching experiences is a timely question for teacher educators. This chapter describes efforts to use the TPACK framework (Mishra & Koehler, 2006) to investigate how students use iPad computers during their student teaching and design appropriate supports. A design-based approach (Sandoval & Bell, 2004) was used over two years with two cohorts of student teachers (N=60). Descriptions of the use of the TPACK framework in this endeavor and findings from surveys and field notes about how and to what degree mobile technology can facilitate activities and interactions in planning, teaching, reflecting, and sharing are included. The case is made for co-learning and co-constructing by student teachers and teacher educators of the various TPACK domains of teacher knowledge in the context of mobile technology. Implications for developing supportive learning environments for 21st century student teachers are also discussed.
Reconceptualizing Learning Designs in Higher Education
Authors: Ostashewski Nathaniel , Dickinson-Delaporte Sonia , Martin Romana
Published: September 2014

This goal of this chapter is to provide a design and development roadmap for the adaptation of traditional classroom activities into engaging iPad-based digital learning activities. Reporting on an ongoing longitudinal case study, the chapter provides an overview of rationale and design considerations of the authentic iPad learning design implementation project, and the outcomes and improvements made over time. The iPad activities described provide further details of the approach taken and adaptations made. Since implementing iPad activities into this higher education environment several terms ago, the lecturer reports significantly higher levels of student engagement. Additionally, students report that the classroom activities in the post-graduate marketing course are authentic, transferrable, and are more engaging due the use of the iPad-based activities.
A PSO Based Incremental Hyper-Sphere Partitioning Approach to Classification
Authors: Zheng Binge , Guan Sheng-Uei , Song Jinghao
Published: September 2014

This paper proposes an incremental hyper-sphere partitioning approach for classification problems. Hyper-spheres that are close to the classification boundaries of a given problem are searched using an incremental approach based upon Particle Swarm Optimization (PSO). This new algorithm is proposed to tackle the difficulty of classification problems caused by the complex pattern relationship with a simplified expert rule structure. We solve classification problems through a combination of hyper-sphere partitioning and a Euclidean-distance based partitioning approach. Moreover, an incremental approach combined with output partitioning and pattern reduction is applied to cope with the curse of dimensionality. The algorithm is tested with seven datasets. The experimental results show that this proposed algorithm outperforms ILEGA (our former research work) and normal GA significantly in the final classification accuracy. In terms of the time complexity, it also gains significant improvement in comparison with ILEGA.
Incremental Hyper-Sphere Partitioning for Classification
Authors: Song Jinghao , Guan Sheng-Uei , Zheng Binge
Published: September 2014

In this paper, an Incremental Hyper-Sphere Partitioning (IHSP) approach to classification on the basis of Incremental Linear Encoding Genetic Algorithm (ILEGA) is proposed. Hyper-spheres approximating boundaries to a given classification problem, are searched with an incremental approach based on a unique combination of genetic algorithm (GA), output partitioning and pattern reduction. ILEGA is used to cope with the difficulty of classification problems caused by the complex pattern relationship and curse of dimensionality. Classification problems are solved by a simple and flexible chromosome encoding scheme which is different from that was proposed in Incremental Hyper-plane Partitioning (IHPP) for classification. The algorithm is tested with 7 datasets. The experimental results show that IHSP performs better compared with those classified using hyper-planes and normal GA.
EFL Teacher's and Learners' Perspectives Towards ATODJ
Authors: Moladoust Elahe
Published: September 2014

This study investigated EFL teachers' and students' perspectives towards Audiotaped Oral Dialogue Journals (ATODJs), as a computer-mediated communication (CMC) and a Mobile-assisted language learning (MALL) task. The data came from 202 entries of ATODJs, gathered from15 female Iranian intermediate EFL learners. Teachers and students' evaluations of the whole program comprised of the qualitative part of the research. The results revealed that the majority of the participants found ATDOJs helpful. The strengths, weaknesses, and the challenges of ATODJs from the teacher's and the participants' viewpoints were discussed. Based on the results of the present study, it is highly recommended that EFL teachers and materials developers incorporate ATODJ tasks in the curriculum.
An Exploratory Study of Factors Affecting Consumer International Online Shopping Behavior
Authors: Jiang Pingjun , Jones David B.
Published: September 2014

Few studies in the literature on electronic commerce provide empirical investigation of consumer behavior in the international online shopping context. This study identifies and discusses factors that influence international online purchases and profile the characteristics of those who purchase and those who do not purchase from online stores overseas in three main categories: the online shopping experiential factors, the international shopping motivational factors, and the international trust attitudinal factors. The international online shoppers tend to highly trust foreign vendors and have high preference of and confidence in online shopping. More importantly, these shoppers are knowledge of shopping sites' hosting countries and strongly believe in those sites' global propensity. The paper makes contributions towards new knowledge and understanding of how international online shoppers differ from non-shoppers.
The Concept of Planning Culture: Analysing How Planners Construct Practical Judgements in a Culturised Context
Authors: Othengrafen Frank
Published: September 2014

Planners make judgements in their daily work – they define a problem, they formulate objectives or implement certain instruments to develop, with and for others, good or desirable places, neighbourhoods, cities or regions. These judgements are affected by both individual and collectively shared cognitive frames, representing the ‘cultural DNA' through which planners perceive the world. To understand and compare how planning practices and judgements are constructed by the interplay of individual and collective frames from various actors and spheres (values of individual planners, norms of planning institutions, general societal values, etc.) in a specific culturised context, a conceptual framework is developed by adopting analytical categories from the fields of organisational sciences or cultural studies. The conceptual framework – consisting of the dimensions: cognitive frames of individual planners and planning institutions; actors and their interactions; the institutional context and the planning system; as well as the underlying societal beliefs, perceptions and values affecting planning and planners' judgements – provides scientists with a new theoretical approach that allows analysing and comparing the situated particularities of planning practices on basis of a consistent system of criteria.
E-Participation in Urban Planning: Getting and Keeping Citizens Involved
Authors: Donders Maud , Hartmann Thomas , Kokx Anita
Published: September 2014

This article addresses an often neglected perspective on e-participation in urban planning: the citizens' perspective. Usually, the debate focuses very much on the planners' perspective. In a case study, two issues are analysed: First, what are the motives of participants and non-participants; second, how citizens' perception of influence and equality in the process affect their satisfaction with it. It is concluded that getting more people involved requires addressing three different types of motives, and that e-participation easily scores high on the perception of equality, but that citizens' perception of influence requires particular attention of the planners.
Free Public Wi-Fi and E-Planning
Authors: Lambert Alex , McQuire Scott , Papastergiadis Nikos
Published: September 2014

Networked media are increasingly pervading public spaces and influencing the way we behave in public. Australian municipalities and cultural institutions have begun deploying free Wi-Fi services hoping they will attract more visitors to public places, aid in curated events, galvanize communities and enhance local economies. In this article we present multi-method research aimed at understanding whether such services can enhance public space and culture, and hence contribute to the public good. We identify multiple forms of positive use which certain kinds of ‘user-centric' services enable. However, many public institutions face problems to do with funding, network models and choice of place which prevent the actualization of these positive outcomes. We consider how e-planning can be mobilized to help such institutions develop virtuous networked public spaces.
Greening the Mediapolis with Media Literacy
Authors: López Antonio
Published: September 2014

In media education there is a deficit in awareness about the connection between media and living systems. Though issues like economics, body image, sexism, racism and gender stereotyping remain significant concerns for media educators and scholars alike, historically the environment has been a peripheral theme in communications studies and associated disciplines. So while new gadgets and software platforms are touted as necessary aspects of cultural citizenship in media literacy discourses, this view of education, empowerment and participation is usually thought of in limited, anthropocentric ways that exclude living systems and sustainability as integral aspects of communication technologies. This essay proposes that media education should enable us to closely analyze the institutions, technological forms, cultural practices and worldview that are shaped by media technology, including how they impact ecological sustainability.
These Clothes Don't Fit!
Authors: Patterson Jennifer
Published: September 2014

This paper argues the need for a transformational revaluing of the rights to the city through an unmaking of social fabric, since upcycling reframes existing power relations based on ownership of land and people and excludes the rights of children and the earth. It highlights the need for environmental education. Indicating that transition requires a paradigm shift, it employs a fractured, feminist bricolage. Operating from within a Western academic perspective it concludes that the work of remaking the city on the basis of social justice is a shifting process of encountering self and others in our own and other worlds.
Narrative of the Pier
Authors: Sta Maria Cecilia Fe L
Published: September 2014

“Locating ourselves in the center of en masse urbanization….” Matnog, Sorsogon, Philippines, primarily a coastal area is not exempted from this socio-cultural shift. And in these changes, people, specifically that of the eight Girls, ages 14 to 18 years old living in the periphery of the coast, begin to question this condition of urbanization that has only created varied and severe strands of poverty in their area. “I look at their photographs and listen to their narrative....” Using Alice McIntyre's photovoice, the Girls took photographs of spaces that represent the concepts of poverty and development. I let them speak of these spaces and they begin to talk about “development” and “poverty,” focusing on the existence of the Pier, the Coast and that of their lives. “Spatiality of the Pier....” Taking the postmodern lens, guided by Edward Soja's notions on spatiality is an attempt to view the unfolding of tensions emanating from urban spaces and their representations. The Pier and that of other spaces become the discursive arena that conjugate non-recognition of positions and conditions between the concepts of “poverty” and “development.” With the Pier as the most imposing space emerges ambiguity and blurry vision affect how the Girls perceive, conceive and live in and along these spaces. Development as assumed to be an existing and workable paradigm through urbanization promise alteration of their condition does not exist for them. What happens is that “poverty” becomes the constant wherein time and space are in crisis; and, the spatiality of the Girls becomes fragmented and pulverized. “IT”: For urbanization as a development agenda does not fulfill its promise to the Girls of Matnog, Sorsogon and to us. This knowledge as conceptualized for them place them in a position and state where they no longer recognize what development is. In this discourse, development, urbanization and spaces that represent them all becomes (in)visible that have become (un)recognizable and (un)familiar for the Girls and for us. This (non)recognition place all these concepts and spaces as an IT.
A Socio-Technical Approach to Evidence Generation in the Use of Video Conferencing in Care Delivery
Authors: Hoare Adam , Eason Ken
Published: September 2014

Care and support services need to respond to the rapidly changing demands of the population and available resources. The authors will present evidence that video conferencing can underpin many of the aspirations for future care delivery. However, if the necessary scale and pace are to be achieved a new model for evidence generation needs to be found. Using the experience of deploying video across health and social care a new model of evidence generation will be proposed based on a socio-technical approach where complexity and human capabilities are features of the intervention. A practice-based approach utilising action research will be used. The model will focus on four dimensions that are key to the success of an intervention using video: Practice, Outcomes, Technology and Evidence. Addressing the interactions between these four dimensions promotes a system that can evolve services that, in cooperation with the video technology platform, can satisfy changing care demands.
A Rule Based Approach for Japanese-Uyghur Machine Translation System
Authors: Nimaiti Maimitili , Izumi Yamamoto
Published: September 2014

Japanese Uyghur machine translation system has been designed and developed using recent rule based approach. Even though Japanese and Uyghur language has many similarities, but there are also some linguistic differences cause serious problems to the word for word translation. In fact, as straightforward word-for-word Japanese-Uighur translation sometimes yields unnatural Uighur sentences. To raise the translation accuracy, the authors propose a word-for-word translation system using subject verb agreement in Uighur. After a brief introduction to the comparative study of Japanese-Uyghur grammars, morphology and syntax, the authors explain their developing of a word to word rule base system. The coverage of this rule base system, the rules for translation, comparison of experimental result between statistical machine translation system and rule base machine translation system are explained. Some practical suffix translation methods solving problems in Uyghur language are also proposed.
The effect of sexual experience on the social representation of sex in Portuguese young adults
Authors: Gomes Alexandra , Nunes Cristina
Published: September 2014

This study aimed to observe the effect of sexual experience on the social representation of sex in Portuguese young adults. According to social representation theory, the central core of the social representation should be the same in all individuals that share a common social ground, however differences should be found in the peripheral system. It was used a free evocation task to assess the social representation of sex in Portuguese individuals aging between 18 and 25 years old. Nine hundred and sixty individuals were grouped by their sexual experience and condom use habits. A prototypical analysis was conducted to assess the structure of the social representation and statistical differences were analyzed using the qui-square independency test to search for an association between the structure and the group evoking it. The results supported the hypothesis of a common central core for all groups that shows a romanticized vision of sex. The differences found in the peripheral system suggest that sexual experience affects the representation of sex in a way that seems clearer to these individuals the necessity of protection when it comes to sex.
Technical Note: Application of positive matrix factor analysis in heterogeneous kinetics studies utilizing the mixed-phase relative rates technique
Authors: Liu Y. , Li S.-M. , Liggio J.
Published: September 2014

Abstract. The mixed-phase relative rates approach for determining aerosol particle organic heterogeneous reaction kinetics is often performed utilizing mass spectral tracers as a proxy for particle-phase reactant concentration. However, this approach may be influenced by signal contamination from oxidation products during the experiment. In the current study, the mixed-phase relative rates technique has been improved by combining a positive matrix factor (PMF) analysis with electron ionization aerosol mass spectrometry (unit-mass resolution), thereby removing the influence of m / z fragments from reaction products on the reactant signals. To demonstrate the advantages of this approach, the heterogeneous reaction between OH radicals and citric acid (CA) was investigated using a photochemical flow tube coupled to a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS). The measured heterogeneous rate constant (k2) of citric acid toward OH was (3.31 ± 0.29) × 10−12 cm3 molecule−1 s−1 at 298 K and (30 ± 3)% relative humidity (RH) and was several times greater than the results utilizing individual m / z fragments. This phenomenon was further evaluated for particulate-phase organophosphates (triphenyl phosphate (TPhP), tris-1,3-dichloro-2-propyl phosphate (TDCPP) and tris-2-ethylhexyl phosphate (TEHP)), leading to k2 values significantly larger than previously reported. The results suggest that heterogeneous kinetics can be significantly underestimated when the structure of the products is highly similar to the reactant and when a non-molecular tracer is measured with a unit-mass resolution aerosol mass spectrometer. The results also suggest that the heterogeneous lifetime of organic aerosol in models can be overestimated due to underestimated OH uptake coefficients. Finally, a comparison of reported rate constants implies that the heterogeneous oxidation of aerosols will be dependent upon a number of factors related to the reaction system, and that a single rate constant for one system cannot be universally applied under all conditions.
Estimation of mineral dust long-wave radiative forcing: sensitivity study to particle properties and application to real cases in the region of Barcelona
Authors: Sicard M. , Bertolín S. , Mallet M. , Dubuisson P. , Comerón A.
Published: September 2014

Abstract. The aerosol radiative effect in the long-wave (LW) spectral range is sometimes not taken into account in atmospheric aerosol forcing studies at local scale because the LW aerosol effect is assumed to be negligible. At regional and global scale this effect is partially taken into account: aerosol absorption is taken into account but scattering is still neglected. However, aerosols with strong absorbing and scattering properties in the LW region, like mineral dust, can have a non-negligible radiative effect in the LW spectral range (both at surface and top of the atmosphere) which can counteract their cooling effect occurring in the short-wave spectral range. The first objective of this research is to perform a sensitivity study of mineral dust LW radiative forcing (RF) as a function of dust microphysical and optical properties using an accurate radiative transfer model which can compute vertically resolved short-wave and long-wave aerosol RF. Radiative forcing simulations in the LW range have shown an important sensitivity to the following parameters: aerosol load, radius of the coarse mode, refractive index, aerosol vertical distribution, surface temperature and surface albedo. The scattering effect has been estimated to contribute to the LW RF up to 18% at the surface and up to 38% at the top of the atmosphere. The second objective is the estimation of the short-wave and long-wave dust RF for 11 dust outbreaks observed in Barcelona. At the surface, the LW RF varies between +2.8 and +10.2 W m−2, which represents between 11 and 26% (with opposite sign) of the SW component, while at the top of the atmosphere the LW RF varies between +0.6 and +5.8 W m−2, which represents between 6 and 26% (with opposite sign) of the SW component.
Determination of interfacial parameters of a soluble particle in a nonideal solution from measured deliquescence and efflorescence humidities
Authors: Hellmuth O. , Shchekin A. K.
Published: September 2014

Abstract. In order to study the growth/shrinking of a hygroscopic nanoparticle during hydration/dehydration in an atmosphere of water vapour we have employed a thermodynamic approach proposed by Shchekin et al. (2008). This approach uses the mechanic and thermodynamic concept of disjoining pressure of thin films and allows, among others, the prediction of the humidity growth factor of both (i) a homogeneous solution droplet with completely dissolved residual core, and (ii) a heterogeneous solution droplet with partially dissolved residual core as a function of the ambient relative humidity. For application to a nanometric sodium chloride particle we have extended the original approach by (i) consideration of the nonideality of the solution through the dependence of molecular volumes of the solvent and solute molecules and the solute and solvent activities on the solution concentration, by (ii) derivation of an equation for the estimation of the efflorescence properties of a homogeneous solution droplet, and by (iii) combination with the empirical power law fittings for the size dependence of the deliquescence and efflorescence relative humidity values by Biskos et al. (2006a). It was demonstrated how the solution/solute interface energy and the correlation length of a thin solution film can be determined from a combination of experimentally determinable efflorescence and deliquescence humidities with the present calculus. The solution/solute interface energy was found to be in close agreement with some previous values reported in the literature, while it strongly differs from data of some other sources. The calculated deliquescence humidity shows a low sensitivity against the choice of the numerical value for the film correlation length. The estimated film correlation length of 1 nm for a nanometric sodium chloride particle with dry particle radius of 5 nm was found to be reconcilable with available a priori estimates of the correlation length from the literature when the measurement uncertainty of the deliquescence humidity is considered. Considering the combination of an extensive calculus, a comprehensive set of thermophysical constraints, and independent measurements of the deliquescence and efflorescence humidities as functions of dry particle radius, the obtained values of the solution/solute interface energy and the correlation length are in close agreement with previous estimations. The humidification of sodium chloride particles in the initial hydration stages was found to be very sensitive against the specification of the disjoining pressure. The enhancement of the wettability of the particle surface leads to an earlier onset of hygroscopic growth.
An evaluation of ozone dry deposition in global scale chemistry climate models
Authors: Hardacre C. , Wild O. , Emberson L.
Published: September 2014

Abstract. Dry deposition to the Earth's surface is an important process from both an atmospheric and biospheric perspective. Dry deposition controls the atmospheric abundance of many compounds as well as their input to vegetative surfaces, thus linking the atmosphere and biosphere. In many atmospheric and Earth system models dry deposition is represented using "resistance in series" schemes developed in the 1980s. These methods have remained relatively unchanged since their development and do not take into account more recent understanding of dry deposition processes that have been gained through field and laboratory based studies. In this study we compare dry deposition of ozone across 15 models which contributed to the HTAP model intercomparison to identify where differences occur. We compare modelled dry deposition of ozone to measurements made at a variety of locations in Europe and North America, noting differences of up to a factor of two but no clear systematic bias over the sites examined. We identify a number of measures that are needed to provide a more critical evaluation of dry deposition fluxes and advance model development.
Dynamical analysis of sea-breeze hodograph rotation in Sardinia
Authors: Moisseeva N. , Steyn D. G.
Published: September 2014

Abstract. This study investigates the diurnal evolution of sea-breeze rotation over an island in the mid-latitudes. Earlier research on sea-breezes in Sardinia shows that the onshore winds around various coasts of the island exhibit both the theoretically predicted clockwise rotation as well as seemingly anomalous anti-clockwise rotation. A non-hydrostatic fully compressible numerical model (WRF) is used to simulate wind fields on and around the island on previously-studied sea-breeze days and is shown to accurately capture the circulation on all coasts. Diurnal rotation of wind is examined and patterns of clockwise and anti-clockwise rotation are identified. A dynamical analysis is performed by extracting individual forcing terms from the horizontal momentum equations. Analysis of several regions around the island shows that the direction of rotation is a result of a complex interaction between near-surface and synoptic pressure gradient, Coriolis and advection forcings. An idealized simulation is performed over an artificial island with dramatically simplified topography, yet similar dimensions and latitude to Sardinia. Dynamical analysis of the idealized case reveals a rather different pattern of hodograph rotation to the real Sardinia, yet similar underlying dynamics. The research provides new insights into the dynamics underlying sea-breeze hodograph rotation, especially in coastal zones with complex topography and/or coastline.
Stratospheric and mesospheric HO2 observations from the Aura Microwave Limb Sounder
Authors: Millán L. , Wang S. , Livesey N. , Kinnison D. , Sagawa H. , Kasai Y.
Published: September 2014

Abstract. This study introduces stratospheric and mesospheric hydroperoxyl radical (HO2) estimates from the Aura Microwave Limb Sounder (MLS) using an offline retrieval (i.e. run separately from the standard MLS algorithm). This new dataset provides two daily zonal averages, one during daytime and one during nighttime, with a varying vertical resolution from about 4 km at 10 hPa to around 14 km at 0.0032 hPa. A description of the methodology and an error analysis are presented. Comparisons against the Whole Atmosphere Community Climate Model (WACCM), the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) and the Far Infrared Spectrometer (FIRS-2) measurements, as well as, photochemical simulations demonstrate the robustness of the retrieval and indicate that the retrieval is sensitive enough to detect mesospheric HO2 layers during both day and night. This new dataset is the first long-term HO2 stratospheric and mesospheric satellite record and it provides needed constraints to help resolve the O3 deficit problem and the "HOx dilemma".
Greenhouse gas emissions from laboratory-scale fires in wildland fuels depend on fire spread mode and phase of combustion
Authors: Surawski N. C. , Sullivan A. L. , Meyer C. P. , Roxburgh S. H. , Polglase P. J.
Published: September 2014

Abstract. Experimental fires were conducted in a combustion wind tunnel facility to explore the role of fire spread mode on the resulting emissions profile from combustion of fine (< 6 mm) Eucalyptus litter fuels. Fires were burnt spreading with the wind (heading fire), perpendicular to the wind (flanking fire) and against the wind (backing fire). Greenhouse gas compounds (i.e. CO2, CH4 and N2O) and CO were quantified using off-axis integrated-cavity-output spectroscopy (off-axis ICOS). A dilution system was employed with the off-axis ICOS technique to prevent spectral broadening of the CO emissions peak and to enable simultaneous quantification of N2O and CO. The forward rate of spread was 20 times faster and the Byram fireline intensity was 20 times higher for heading fires compared to flanking and backing fires. Emissions factors calculated using a carbon mass balance technique (along with statistical testing) showed that most of the carbon was emitted as CO2, with heading fires emitting 17% more CO2 than flanking and 9.5% more CO2 than backing fires, and about twice as much CO. Heading fires had less than half as much carbon remaining in combustion residues. Statistically significant differences in CH4 and N2O emissions factors were not found with respect to fire spread mode. Emissions factors calculated per unit of dry fuel consumed showed that combustion phase (i.e. flaming or smouldering) had a statistically significant impact, with CO and N2O emissions increasing during smouldering combustion and CO2 emissions factors decreasing. Findings on the equivalence of different emissions factor reporting methods are discussed along with the impact of our results for emissions accounting. The primary implication of this study is that prescribed fire practices might be modified to mitigate greenhouse gas emissions from forested landscapes by the preferential application of flanking and backing fires over heading fires. Future research could involve wind tunnel testing with more realistic fuel architectures and could also quantify particulate emissions with different fire spread modes.
Mass specific optical absorption coefficients of mineral dust components measured by a multi wavelength photoacoustic spectrometer
Authors: Utry N. , Ajtai T. , Pintér M. , Tombácz E. , Illés E. , Bozóki Z. , Szabó G.
Published: September 2014

Abstract. Mass specific optical absorption coefficients of various mineral dust components including silicate clays (illite, kaolin and bentonite), oxides (quartz, hematite and rutile), and carbonate (limestone) were determined at wavelengths of 1064, 532, 355 and 266 nm. These values were calculated from aerosol optical absorption coefficients measured by a multi-wavelength photoacoustic (PA) instrument, the mass concentration and the number size distribution of the generated aerosol samples as well as the size transfer functions of the measuring instruments. These results are expected to have considerable importance in global radiative forcing calculations. They can also serve as reference for validating calculated wavelength dependent imaginary parts (κ) of complex refractive indices which up to now have been typically deduced from bulk phase measurements by using indirect measurement methods. Accordingly, the presented comparison of the measured and calculated aerosol optical absorption spectra revealed the strong need for standardized sample preparation and measurement methodology in case of bulk phase measurements.
Use of neural networks in ground-based aerosol retrievals from multi-angle spectropolarimetric observations
Authors: Di Noia A. , Hasekamp O. P. , van Harten G. , Rietjens J. H. H. , Smit J. M. , Snik F. , Henzing J. S. , de Boer J. , Keller C. U. , Volten H.
Published: September 2014

Abstract. In this paper, the use of a neural network algorithm for the retrieval of the aerosol properties from ground-based spectropolarimetric measurements is discussed. The neural network is able to retrieve the aerosol properties with an accuracy that is almost comparable to that of an iterative retrieval. By using the outcome of the neural network as a first guess of the iterative retrieval scheme, the accuracy of the fine and coarse mode optical thickness are further improved while for the other parameters the improvement is small or absent. The resulting scheme (neural network + iterative retrieval) is compared to the original one (look-up table + iterative retrieval) on a set of simulated ground-based measurements, and on a small set of real observations carried out by an accurate ground-based spectropolarimeter. The results show that the use of a neural network based first guess leads to an increase in the number of converging retrievals, and possibly to more accurate estimates of the aerosol effective radius and complex refractive index.
Cluster observations of the substructure of a flux transfer event: analysis of high-time-resolution particle data
Authors: Varsani A. , Owen C. J. , Fazakerley A. N. , Forsyth C. , Walsh A. P. , André M. , Dandouras I. , Carr C. M.
Published: September 2014

Abstract. Flux transfer events (FTEs) are signatures of transient reconnection at the dayside magnetopause, transporting flux from the dayside of the magnetosphere into the magnetotail lobes. They have previously been observed to contain a combination of magnetosheath and magnetospheric plasma. On 12 February 2007, the four Cluster spacecraft were widely separated across the magnetopause and observed a crater-like FTE as they crossed the Earth's dayside magnetopause through its low-latitude boundary layer. The particle instruments on the Cluster spacecraft were in burst mode and returning data providing 3-D velocity distribution functions (VDFs) at 4 s resolution during the observation of this FTE. Moreover, the magnetic field observed during the event remained closely aligned with the spacecraft spin axis and thus we have been able to use these 3-D data to reconstruct nearly full pitch angle distributions of electrons and ions at high time resolution (up to 32 times faster than available from the normal mode data stream). These observations within the boundary layer and inside the core of the FTE show that both the interior and the surrounding structure of the FTE consist of multiple individual layers of plasma, in greater number than previously identified. Our observations show a cold plasma inside the core, a thin layer of antiparallel-moving electrons at the edge of FTE itself, and field-aligned ions with Alfvénic speeds at the trailing edge of the FTE. We discuss the plasma characteristics in these FTE layers, their possible relevance to the magnetopause reconnection processes and attempt to distinguish which of the various different FTE models may be relevant in this case. These data are particularly relevant given the impending launch of NASA's MMS mission, for which similar observations are expected to be more routine.
Monitoring of carbon dioxide fluxes in a subalpine grassland ecosystem of the Italian Alps using a multispectral sensor
Authors: Sakowska K. , Vescovo L. , Marcolla B. , Juszczak R. , Olejnik J. , Gianelle D.
Published: September 2014

Abstract. The study investigates the potential of a commercially available proximal sensing system – based on a 16-band multispectral sensor – for monitoring mean midday gross ecosystem production (GEPm) in a subalpine grassland of the Italian Alps equipped with an eddy covariance flux tower. Reflectance observations were collected for 5 consecutive years, characterized by different climatic conditions, together with turbulent carbon dioxide fluxes and their meteorological drivers. Different models based on linear regression (vegetation indices approach) and on multiple regression (reflectance approach) were tested to estimateGEPm from optical data. The overall performance of this relatively low-cost system was positive. Chlorophyll-related indices including the red-edge part of the spectrum in their formulation (red-edge normalized difference vegetation index, NDVIred-edge; chlorophyll index, CIred-edge) were the best predictors of GEPm, explaining most of its variability during the observation period. The use of the reflectance approach did not lead to considerably improved results in estimating GEPm: the adjusted R2 (adjR2) of the model based on linear regression – including all the 5 years – was 0.74, while the adjR2 for the multiple regression model was 0.79. Incorporating mean midday photosynthetically active radiation (PARm) into the model resulted in a general decrease in the accuracy of estimates, highlighting the complexity of the GEPm response to incident radiation. In fact, significantly higher photosynthesis rates were observed under diffuse as regards direct radiation conditions. The models which were observed to perform best were then used to test the potential of optical data for GEPm gap filling. Artificial gaps of three different lengths (1, 3 and 5 observation days) were introduced in the GEPm time series. The values of adjR2 for the three gap-filling scenarios showed that the accuracy of the gap filling slightly decreased with gap length. However, on average, the GEPm gaps were filled with an accuracy of 73% with the model fed with NDVIred-edge, and of 76% with the model using reflectance at 681, 720 and 781 nm and PARm data.
Impact of sea ice on the marine iron cycle and phytoplankton productivity
Authors: Wang S. , Bailey D. , Lindsay K. , Moore J. K. , Holland M.
Published: September 2014

Abstract. Iron is a key nutrient for phytoplankton growth in the surface ocean. At high latitudes, the iron cycle is closely related to the dynamics of sea ice. In recent decades, Arctic sea ice cover has been declining rapidly and Antarctic sea ice has exhibited large regional trends. A significant reduction of sea ice in both hemispheres is projected in future climate scenarios. In order to adequately study the effect of sea ice on the polar iron cycle, sea ice bearing iron was incorporated in the Community Earth System Model (CESM). Sea ice acts as a reservoir for iron during winter and releases the trace metal to the surface ocean in spring and summer. Simulated iron concentrations in sea ice generally agree with observations in regions where iron concentrations are relatively low. The maximum iron concentrations simulated in Arctic and Antarctic sea ice are much lower than observed, which is likely due to underestimation of iron inputs to sea ice or missing mechanisms. The largest iron source to sea ice is suspended sediments, contributing fluxes of iron of 2.2 × 108 mol Fe month−1 in the Arctic and 4.1 × 106 mol Fe month−1 in the Southern Ocean during summer. As a result of the iron flux from ice, iron concentrations increase significantly in the Arctic. Iron released from melting ice increases phytoplankton production in spring and summer and shifts phytoplankton community composition in the Southern Ocean. Results for the period of 1998 to 2007 indicate that a reduction of sea ice in the Southern Ocean will have a negative influence on phytoplankton production. Iron transport by sea ice appears to be an important process bringing iron to the central Arctic. The impact of ice to ocean iron fluxes on marine ecosystems is negligible in the current Arctic Ocean, as iron is not typically the growth-limiting nutrient. However, it may become a more important factor in the future, particularly in the central Arctic, as iron concentrations will decrease with declining sea ice cover and transport.