Determination of kaolinite and halloysite crystallite size with X-Ray diffraction: implications for industrial applications

To μέσο πάχος και η κατανομή παχών αργιλικών κλασμάτων καολινίτη και αλλουσίτη προσδιορίστηκαν με περιθλασιμετρία ακτίνων-Χ, με χρήση της τεχνικής Bertaut- Warren-Averbach (BWA), η οποία προσδιορίζει τους τομείς συναφούς σκέδασης (CSD). Το μέσο πάχος του καολινίτη και αλλουσίτη ήταν αντίστοιχα 11.8 nm and 10.6 nm, ενώ οι κρύσταλλοι των δύο ορυκτών εμφανίζουν λογαριθμοκανονικές κατανομές πάχους. Το μέσο μέγεθος κόκκου που προσδιορίστηκε με τη μέθοδο της σκέδασης δέσμης laser ήταν πολύ μεγαλύτερο ενώ η κοκκομετρική κατανομή χαρακτηρίζεται από δύο πληθυσμούς (bimodal) λόγω συσσωμάτωσης. Η συσσωμάτωση επηρεάζει αρνητικά οπτικές ιδιότητες ορυκτών κόνεων, όπως η φωτεινότητα λόγω διάχυσης του φωτός. Μεγαλύτερη απόκλιση στο μέγεθος κόκκου που προσδιορίζεται με τις δύο τεχνικές μπορεί να εξηγεί τη μικρή φωτεινότητας που παρατηρείται σε ορισμένα λευκά υλικά.Mean thickness and thickness distribution of kaolinite and halloysite clay fractions was obtained by X-ray diffraction, using the Bertaut-Warren-Averbach (BWA) technique, which determines the coherent scattering domain (CSD). Mean thickness of kaolinite and halloysite was 11.8 nm and 10.6 nm respectively and both minerals are characterized by lognormal thickness distribution. Laser scattering, which is often used by the industry, yielded considerably greater mean grain size and bimodal size distribution for both materials due to particle agglomeration. Agglomeration affects optical properties of mineral powders such as brightness adversely, because of light diffusion. A greater discrepancy in particle size determined by the two techniques might explain lower brightness observed in white powders

Attribution of human-induced dynamical and thermodynamical contributions in extreme weather events

This is the final version. Available on open access from IOP Publishing via the DOI in this recordWe present a new method that allows a separation of the attribution of human influence in extreme events into changes in atmospheric flows and changes in other processes. Assuming two data sets of model simulations or observations representing a natural, or 'counter-factual' climate, and the actual, or 'factual' climate, we show how flow analogs used across data sets can provide quantitative estimates of each contribution to the changes in probabilities of extreme events. We apply this method to the extreme January precipitation amounts in Southern UK such as were observed in the winter of 2013/2014. Using large ensembles of an atmospheric model forced by factual and counterfactual sea surface temperatures, we demonstrate that about a third of the increase in January precipitation amounts can be attributed to changes in weather circulation patterns and two thirds of the increase to thermodynamic changes. This method can be generalized to many classes of events and regions and provides, in the above case study, similar results to those obtained in Schaller et al (2016 Nat. Clim. Change 6 627-34) who used a simple circulation index, describing only a local feature of the circulation, as in other methods using circulation indices (van Ulden and van Oldenborgh 2006 Atmos. Chem. Phys. 6 863-81).European Union FP7French Ministry of EcologyEuropean Research Council (ERC

The algebraic decay of equatorial Rossby waves in a shear flow

Through numerical integration, we show that equatorial Rossby waves, like their midlatitude counterparts, decay algebraically in the limit t --> [infinity] in a linear shear flow. For small times, the growth expected for some components does not translate into any growth of the wave disturbance as a whole when the initial conditions has a broad Fourier spectrum. The conclusion is that Rossby waves will amplify with time only when the mean flow has an inflection point or when the initial eddy field is strongly concentrated in long waves tilted against the shear.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26587/1/0000128.pd

Upgrade of the HadGEM3-A based attribution system to high resolution and a new validation framework for probabilistic event attribution

We present a substantial upgrade of the Met Office system for the probabilistic attribution of extreme weather and climate events with higher horizontal and vertical resolution (60 km mid-latitudes and 85 vertical levels), the latest Hadley Centre atmospheric and land model (ENDGame dynamics with GA6.0 science and JULES at GL6.0) as well as an updated forcings set. A new set of experiments designed for the evaluation and implementation of an operational attribution service are described which consist of pairs of multi-decadal stochastic physics ensembles continued on a season by season basis by large ensembles that are able to sample extreme at- mospheric states possible in the recent past. Diagnostics from these experiments form the HadGEM3-A contribution to the international Climate of the 20th Century Plus (C20Cþ) project and were analysed under the European Climate and Weather Events: Interpretation and Attribution (EUCLEIA) event attribution project as well as contributing to the Climate Science for Service Partnership (CSSP)-China programme. After discussing the framing issues surrounding questions that can be asked with our system we construct a novel approach to the evaluation of atmosphere-only ensembles intended for event attribution, in the process highlighting and clarifying the distinction between hindcast skill and model performance. A framework based around assessing model representation of predictable components and ensuring exchangeability of model and real world statistics leads to a form of detection and attribution to boundary condition forcing as a means of quantifying one degree of freedom of potential model error and allowing for the bias correction of event probabilities and resulting probability ratios. This method is then applied systematically across the globe to assess contributions from anthropogenic influence and specific boundary conditions to the changing probability of observed and record seasonal mean temperatures of four recent 3-month seasons from March 2016–February 2017

DADA: data assimilation for the detection and attribution of weather and climate-related events

A new nudging method for data assimilation, delay‐coordinate nudging, is presented. Delay‐coordinate nudging makes explicit use of present and past observations in the formulation of the forcing driving the model evolution at each time step. Numerical experiments with a low‐order chaotic system show that the new method systematically outperforms standard nudging in different model and observational scenarios, also when using an unoptimized formulation of the delay‐nudging coefficients. A connection between the optimal delay and the dominant Lyapunov exponent of the dynamics is found based on heuristic arguments and is confirmed by the numerical results, providing a guideline for the practical implementation of the algorithm. Delay‐coordinate nudging preserves the easiness of implementation, the intuitive functioning and the reduced computational cost of the standard nudging, making it a potential alternative especially in the field of seasonal‐to‐decadal predictions with large Earth system models that limit the use of more sophisticated data assimilation procedures

Characterising loss and damage from climate change

Policy-makers are creating mechanisms to help developing countries cope with loss and damage from climate change, but the negotiations are largely neglecting scientific questions about what the impacts of climate change actually are. Mitigation efforts have failed to prevent the continued increase of anthropogenic greenhouse gas (GHG) emissions. Adaptation is now unlikely to be sufficient to prevent negative impacts from current and future climate change1. In this context, vulnerable nations argue that existing frameworks to promote mitigation and adaptation are inadequate, and have called for a third international mechanism to deal with residual climate change impacts, or “loss and damage”2. In 2013, the United Nations Framework Convention on Climate Change (UNFCCC) responded to these calls and established the Warsaw International Mechanism (WIM) to address loss and damage from the impacts of climate change in developing countries3. An interim Executive Committee of party representatives has been set up, and is currently drafting a two-year workplan comprising meetings, reports, and expert groups; and aiming to enhance knowledge and understanding of loss and damage, strengthen dialogue among stakeholders, and promote enhanced action and support. Issues identified as priorities for the WIM thus far include: how to deal with non-economic losses, such as loss of life, livelihood, and cultural heritage; and linkages between loss and damage and patterns of migration and displacement2. In all this, one fundamental issue still demands our attention: which losses and damages are relevant to the WIM? What counts as loss and damage from climate change

Potential Impacts on Accessibility and Consumer Surplus of Improvements of the European Railway System

AbstractIt is widely accepted that “transport infrastructure endowment influences competiveness of a Region; the provision of investment in transport infrastructure entails positive effects on productivity and growth, even if on the other side, heavy infrastructures (as railway lines) could affect negatively on the environment” (5th Cohesion Report, 2010). This article aims to explore the potential impact of improvements of the passenger rail network in order to evaluate how these could potentially increase accessibility and consumer surplus in EU regions; it summarizes the results of the model simulations carried out with a combination of the TRANSTOOLS rail network and the assignment module of Traffic Analyst.Three different scenarios have been tested by changing speeds on the whole network. The post-processing analysis has been carried out with utilities developed in Matlab, while the results for each zone (at NUTS3 level) have also been reported in easy-to-read ArcGIS maps. The outcomes provide insight into how the demand for passenger rail transport would react and where the highest benefits and costs, in terms of accessibility and consumer surplus gains, can be expected. This information, in turn, can be useful for the prioritization of investment needs and the identification of parts of the rail passenger market where new demand may be generated