A simple framework for modelling the photochemical response to solar spectral irradiance variability in the stratosphere

The stratosphere is thought to play a central role in the atmospheric response to solar irradiance variability. Recent observations suggest that the spectral solar irradiance (SSI) variability involves significant time-dependent spectral variations, with variable degrees of correlation between wavelengths, and new reconstructions are being developed. In this paper, we propose a simplified modelling framework to characterise the effect of short term SSI variability on stratospheric ozone. We focus on the pure photochemical effect, for it is the best constrained one. The photochemical effect is characterised using an ensemble simulation approach with multiple linear regression analysis. A photochemical column model is used with interactive photolysis for this purpose. Regression models and their coefficients provide a characterisation of the stratospheric ozone response to SSI variability and will allow future inter-comparisons between different SSI reconstructions. As a first step in this study, and to allow comparison with past studies, we take the representation of SSI variability from the Lean (1997) solar minimum and maximum spectra. First, solar maximum-minimum response is analysed for all chemical families and partitioning ratios, and is compared with past studies. The ozone response peaks at 0.18 ppmv (approximately 3%) at 37 km altitude. Second, ensemble simulations are regressed following two linear models. In the simplest case, an adjusted coefficient of determination <span style="border-top: 1px solid #000; color: #000;">R</span><sup>2</sup> larger than 0.97 is found throughout the stratosphere using two predictors, namely the previous day's ozone perturbation and the current day's solar irradiance perturbation. A better accuracy (<span style="border-top: 1px solid #000; color: #000;">R</span><sup>2</sup> larger than 0.9992) is achieved with an additional predictor, the previous day's solar irradiance perturbation. The regression models also provide simple parameterisations of the ozone perturbation due to SSI variability. Their skills as proxy models are evaluated independently against the photochemistry column model. The bias and RMS error of the best regression model are found smaller than 1% and 15% of the ozone response, respectively. Sensitivities to initial conditions and to magnitude of the SSI variability are also discussed

Conservation and diversity in expression of candidate genes regulating socially-induced female-male sex change in wrasses

International audienc

Learning about A level physics students’ understandings of particle physics using concept mapping

This paper describes a small-scale piece of research using concept mapping to elicit A level students' understandings of particle physics. Fifty-nine year 12 (16- and 17 year-old) students from two London schools participated. The exercise took place during school physics lessons. Students were instructed how to make a concept map and were provided with 24 topic-specific key words. Students' concept maps were analysed by identifying the knowledge propositions they represented, enumerating how many students had made each one, and by identifying errors and potential misconceptions, with reference to the specification they were studying. The only correct statement made by a majority of students in both schools was that annihilation takes place when matter and antimatter collide, although there was evidence that some students were unable to distinguish between annihilation and pair production. A high proportion of students knew of up, down and strange quarks, and that the electron is a lepton. However, some students appeared to have a misconception that everything is made of quarks. Students found it harder to classify tau particles than they did electrons and muons. Where students made incorrect links about muons and tau particles their concept maps suggested that they thought they were mesons or quarks

Metal-Substituted Microporous Aluminophosphates

This chapter aims to present the zeotypes aluminophosphates (AlPOs) as a complementary alternative to zeolites in the isomorphic incorporation of metal ions within all-inorganic microporous frameworks as well as to discuss didactically the catalytic consequences derived from the distinctive features of both frameworks. It does not intend to be a compilation of either all or the most significant publications involving metal-substituted microporous aluminophosphates. Families of AlPOs and zeolites, which include metal ion-substituted variants, are the dominant microporous materials. Both these systems are widely used as catalysts, in particular through aliovalent metal ions substitution. Here, some general description of the synthesis procedures and characterization techniques of the MeAPOs (metal-contained aluminophosphates) is given along with catalytic properties. Next, some illustrative examples of the catalytic possibilities of MeAPOs as catalysts in the transformation of the organic molecules are given. The oxidation of the hardly activated hydrocarbons has probably been the most successful use of AlPOs doped with the divalent transition metal ions Co2+, Mn2+, and Fe2+, whose incorporation in zeolites is disfavoured. The catalytic role of these MeAPOs is rationalized based on the knowledge acquired from a combination of the most advanced characterization techniques. Finally, the importance of the high specificity of the structure-directing agents employed in the preparation of MeAPOs is discussed taking N,N-methyldicyclohexylamine in the synthesis of AFI-structured materials as a driving force. It is shown how such a high specificity could be predicted and how it can open great possibilities in the control of parameters as critical in catalysis as crystal size, inter-and intracrystalline mesoporosity, acidity, redox properties, incorporation of a great variety of heteroatom ions or final environment of the metal site (surrounding it by either P or Al)

Remote sensing of carbon monoxide vehicle emissions

The University of Denver's remote sensor for automobile exhaust emissions has been used to obtain valid model year (defined here as the year of first registration) and emissions data from roadside locations in Middlesbrough and London. Mean carbon monoxide emissions have been plotted against model year to determine if there is a relationship between mean pollutant emissions and the age of the vehicle. The results initially showed a large degree of scatter and no inference, concerning age and emissions, could be made. This can be largely attributed to the older vehicles in the fleet. Older vehicles were then omitted from an additional investigation providing a much stronger relationship with R2 values of 0.88 being calculated for London and 0.77 for Middlesbrough. Analyses of model year fleet emissions were also undertaken. It was demonstrated that old vehicles do not contribute significantly to fleet emissions. Pre-1983 registered vehicles contributed only 9% of total fleet emissions in Middlesbrough and only 21% of total fleet emissions in London. It was also shown that the vast majority of fleet emissions come from a small number of highly polluting new vehicles (quintile 5). Quintile 5 for model year 1989 represented 140 vehicles (2% of the measured fleet) which contributed to 10.6% of fleet emissions at the Middlesbrough site

Fundamentals of Maxwell's kinetic theory of a simple monatomic gas treated as a branch of rational mechanics

Fundamentals of MaxwellÆs kinetic theory of a simple monatomic ga

The local structure of tetrahedral Co(III): A detailed crystal structure investigation of K₅Co(III)W₁₂O₄₀·20H₂O

Crystal structure of (K5CoW12O40)-W-III. 20H2O is obtained from a detailed single-crystal study. The interatomic distance, in particular the Co(III)-O distance obtained from the present study is in close agreement with the Co K-edge EXAFS data of the title compound. This material will serve as a good model system for understanding the redox properties of microporous cobalt-substituted aluminophosphate catalysts, since the title compound is noted as a rare example of Co(III) in tetrahedral coordination

On the advantages of the use of the three-element detector system for measuring EDXRD patterns to follow the crystallisation of open-framework structures

Time-resolved energy-dispersive X-ray diffraction (EDXRD) studies, employing a new detector technology, of a range of crystallisations of open framework materials are described. We consider four distinct categories of phenomena where new information has been gained specifically from the use of the multi-element (as opposed to the single element) detector system. The systems investigated are: (a) the competitive formation of small-pore and large-pore aluminophosphates (AlPO's), and the effect of concentration of Co-II in the mother liquor (precursor gel) in directing the relative amounts of AlPO-18 (AEI) and chabazite (CHA) structures that are formed; (b) the influence of both template (structure directing) molecules and synthesis time on the stabilities of the AlPO-5 (AFI) structures; (c) a study of both the rate of formation of the open framework titanosilicate (ETS-10) structure and the dissociation rate of crystalline TiO2 used in the preparation of ETS-10; and (d) tracking of the intermediate formed during the synthesis of the gallophosphate structure known as ULM-3. The advantages of using a three-element detector configuration are illustrated