Cassini VIMS observations of latitudinal and hemispheric variations in Saturn’s infrared auroral intensity

The intensity of Saturn’s infrared aurora is investigated using Cassini VIMS images acquired during October 2006–February 2009. Polar and main oval auroral regions were defined in both hemispheres, which extend between 0–10° and 10–25° co-latitude, respectively. Average intensities were computed for these regions and compared. While the northern and southern main oval regions covered a similar range of intensities, the southern main oval was on average more intense by a factor of ∼1.3. The emission from the southern polar region was usually less intense than the main oval emissions, while this was only the case for approximately half of the northern hemisphere images. The northern hemisphere polar region displayed intensities more than twice as high as those in the south and the difference between the two hemispheres was most pronounced on the dayside. In general, more intense polar emissions were accompanied by more intense main oval emissions. Possible explanations for the hemispheric and latitudinal differences are discussed in terms of particle energies and fluxes, ionospheric conductivity, temperature and magnetic field strength.     

Ørkenspredningen i Sudan-Sahel regionen—et af tidens alvorlige problemer/Et spændende og markant 100 års minde—om et helt fantastisk menneske!/De fynske landsbyers historie

Erland Porsmose: De fynske landsbyers historie: i dyrkningsfællesskabets tid. Odense University studies in history and social sciences, Vol. 109.     

Risk and vulnerability analysis in practice: evaluation of analyses conducted in Swedish municipalities

Risk and vulnerability analysis (RVA) can benefit the process of preventing and preparing for disasters, both by generating a basis for making decisions and by enhancing risk awareness, safety culture and response capacity through the RVA process itself. In studying and understanding the practices related to RVA, insights can be gained regarding ways in which the RVA can be improved in society, as well as into how methods for RVA can be designed to suit the particular context. However, studies of this sort are rare. This paper presents an evaluation of RVA performed by Swedish municipalities, which are important actors in the Swedish emergency management system. This is done by employing a systematic, design science approach outlined in the paper. Document studies and interviews were used to collect data on the analyses performed by the municipalities, and the evaluation shows that there is room for improvement. The results can be especially relevant for municipalities developing their RVA practices, as well as for other actors performing similar types of analyses.     

Predicting the properties of the remnants of dissipative galaxy mergers

We construct a physically motivated model for predicting the properties of the remnants of gaseous galaxy mergers, given the properties of the progenitors and the orbit. The model is calibrated using a large suite of smoothed particle hydrodynamics (SPH) merger simulations. It implements generalized energy conservation while accounting for dissipative energy losses and star formation. The dissipative effects are evaluated from the initial gas fractions and from the orbital parameters via an 'impulse' parameter, which characterizes the strength of the encounter. Given the progenitor properties, the model predicts the remnant stellar mass, half-mass radius and velocity dispersion to an accuracy of 25 per cent. The model is valid for both major and minor mergers. We provide an explicit recipe for semi-analytic models of galaxy formation.     

Incorporating multiple observations for distributed hydrologic model calibration: An approach using a multi-objective evolutionary algorithm and clustering

The use of distributed data for model calibration is becoming more popular in the advent of the availability of spatially distributed observations. Hydrological model calibration has traditionally been carried out using single objective optimisation and only recently has been extended to a multi-objective optimisation domain. By formulating the calibration problem with several objectives, each objective relating to a set of observations, the parameter sets can be constrained more effectively. However, many previous multi-objective calibration studies do not consider individual observations or catchment responses separately, but instead utilises some form of aggregation of objectives. This paper proposes a multi-objective calibration approach that can efficiently handle many objectives using both clustering and preference ordered ranking. The algorithm is applied to calibrate the MIKE SHE distributed hydrologic model and tested on the Karup catchment in Denmark. The results indicate that the preferred solutions selected using the proposed algorithm are good compromise solutions and the parameter values are well defined. Clustering with Kohonen mapping was able to reduce the number of objective functions from 18 to 5. Calibration using the standard deviation of groundwater level residuals enabled us to identify a group of wells that may not be simulated properly, thus highlighting potential problems with the model parameterisation.     

Efficient global matrix approach to the computation of synthetic seismograms

Summary. A numerically efficient global matrix approach to the solution of the wave equation in horizontally stratified environments is presented. The field in each layer is expressed as a superposition of the field produced by the sources within the layer and an unknown field satisfying the homogeneous wave equations, both expressed as integral representations in the horizontal wavenumber. The boundary conditions to be satisfied at each interface then yield a linear system of equations in the unknown wavefield amplitudes, to be satisfied at each horizontal wavenumber. As an alternative to the traditional propagator matrix approaches, the solution technique presented here yields both improved efficiency and versatility. Its global nature makes it well suited to problems involving many receivers in range as well as depth and to calculations of both stresses and particle velocities. The global solution technique is developed in close analogy to the finite element method, thereby reducing the number of arithmetic operations to a minimum and making the resulting computer code very efficient in terms of computation time. These features are illustrated by a number of numerical examples from both crustal and exploration seismology.     

Correction to: Microphysics and Optical Attenuation in Fog: Observations from Two Coastal Sites

Boundary-Layer Meteorology -     

The distribution and relative toxic potential of organic chemicals in a PCB contaminated bay

For reliable monitoring of environmental improvement, the PCB contaminated bay Orserumsviken on Sweden's Baltic coast was investigated prior to remediation. We examined PCB congener patterns and the relative toxic potential of PCBs in extracts of three matrices: bottom sediment, settling particulate matter and the dissolved phase (obtained from semi-permeable membrane devices). Congener patterns were similar in all matrices. Three fractions were isolated from the extracts: (1) aliphatic and monocyclic aromatic compounds (MAC-fraction), (2) dicyclic aromatic compounds (DAC-fraction), including PCBs, and (3) polycyclic aromatic compounds (PAC-fraction), including PAHs. Total extracts and fractions were injected into newly fertilised rainbow trout eggs. At larval stage, hepatic EROD activities were quantified. Though high, the PCB contamination could explain only an estimated 1-5% of the total EROD induction. The order of EROD induction potential was: total extract > PAC-fraction > DAC-fraction > MAC-fraction in all matrices, suggesting that in Orserumsviken PACs made a larger contribution to the EROD induction potential than PCBs and other DACs.     

Hydrogen incorporation in orthopyroxene: interaction of different trivalent cations

The incorporation of hydrogen into ferrosilite, Fe-bearing enstatite and orthopyroxene containing different trivalent cations (Cr³⁺ and Al³⁺, Cr³⁺ and Fe³⁺) was investigated experimentally at 25 kbar. Hydrogen concentration was determined by FTIR-spectroscopy on oriented crystal sections and by secondary ion mass spectroscopy, whereas Mößbauer spectroscopy and optical spectroscopy were used to characterise the valence state of Fe in orthopyroxene. Results suggest that hydrogen incorporation in ferrosilite is achieved by a similar mechanism as in pure enstatite. In Cr-bearing samples, however, hydrogen incorporation is reduced by the presence of other trivalent cations by an increased tendency to form Tschermaks substitutions, e.g. Si _T ⁴⁺ + Mg _M1 ²⁺ ? Al _T ³⁺ + Cr _M1 ³⁺ . Thus, hydrogen solubility in natural orthopyroxenes from the Earth’s mantle, containing significant amounts of Cr³⁺, Al³⁺, and Fe³⁺, may be much more limited than expected from their trivalent cation content, as a large fraction of the trivalent cations does not participate in H-incorporating reactions as 2 Mg _M1 ²⁺ ? M _M1 ³⁺ + V_M1 + H _i ⁺ .