Future projections of temperature-related climate change impacts on the railway network of Great Britain

Great Britain’s main line railway network is known to experience various temperature-related impacts, e.g. track buckling and overhead power line sag at high ambient temperatures. Climate change could alter the frequency of occurrence of these impacts. We have therefore investigated the climate change impact on various temperature-related issues, identified during workshops with rail industry specialists, using a perturbed physics ensemble (PPE) of the Met Office’s regional climate model (RCM), HadRM3. We have developed novel approaches to combine RCM data with railway industry knowledge, typically by identifying key meteorological thresholds of interest and analysing exceedance of these out to the 2040s. We performed a statistical analysis of the projected changes for each issue, via bootstrapping of the unperturbed PPE member. Although neither the PPE nor the bootstrapping analysis samples the full range of uncertainty in the projections, they nonetheless provide complementary perspectives on the suitability of the projections for use in decision-making. Our main findings include projected increases in the summertime occurrence of temperature conditions associated with (i) track buckling, (ii) overhead power line sag, (iii) exposure of outdoor workers to heat stress, and (iv) heat-related delays to track maintenance; and (v) projected decreases in the wintertime occurrence of temperatures conditions associated with freight train failure owing to brake problems. For (i), the statistical significance varied with track condition and location; for (ii) and (iii), with location; and for (iv) and (v), projected changes were significant across Great Britain. As well as assessing the changes in climate-related hazard, information about the vulnerability of the network to past temperature-related incidents has been summarised. Combining the hazard and vulnerability elements will eventually support a climate risk assessment for the industry.     

Late Miocene lacustrine sedimentation in the Mytilinii Basin,Samos Island,Greece

The Mytilinii Basin, eastern Samos Island, Greece, is one of many basins that developed in southeastern Europe during the Upper Neogene. The oldest lacustrine portion is of Late Miocene age, and besides tuffs, includes bituminous limestones, marlstones, dolostones and porcelanites of the Pythagorion Formation, and the limestones and diatomites of the overlying Hora Beds. Younger sedimentary rocks of Turolian through Pliocene age partially covered the Pythagorion Formation and Hora Beds (PFHB). Diatom floras range from well preserved to highly corroded and from sparse to abundant. The main taxa include Cyclotella aegaea, C. aegaea var. pythagoria, an unidentified Cyclotella and Nitzschia frustulum, and less common Epithemia turgida, E. reichelti, Synedra ulna, Tryblionella granulata, Encyonema silesiaca, Diploneis ovalis and Cocconeis placentula. Chrysophyte cysts, Hydrobia molluscs and trace fossils occur sporadically. The environmental evolution of the PFHB can be divided into three major stages. Fluctuating shallow to deeper waters in a saline lake characterized Stage A. Saline lake and playa environments with evidence for frequent earthquake events in the form of convolute bedding, drape folds and brecciated sediments characterized Stage B. During Stage C, the lake may have partially or completely split into two separate lakes. In the southeast, a saline playa passed laterally into a deeper-water lake. Locally, fresher-water ponds occurred. Subsequently, a deeper, possibly oligotrophic lake developed. In contrast, a saline lake with abundant diatoms formed in the northwest of the basin, in which diatom blooms led to whiting events and deposition of carbonate laminae. Cyclotella dominated the early floras in this water body, with later assemblages being co-dominated by Cyclotella and Nitzschia frustulum, possibly reflecting seasonal changes. Sedimentation was terminated by uplift and (or) increasing aridity associated with the Messinian Salinity Crisis.     

Synthesis of galactic stellar populations and expected constraints from infrared surveys

Models of population synthesis for the Galaxy have been developed in order to understand galactic structure and evolution. They allow to test scenarii of evolution by comparisons between model predictions and observed distributions. Forthcoming near-infrared surveys will enormously increase the amount of information about the distributions of late type stars in the Galaxy. We show here how population synthesis models will help to analyse these surveys and to interprete them in terms of mass function, star formation history and stellar evolution.     

Geology and desert fieldwork in Oman

Collecting geological data in the desert of east-central Oman is very different from working in temperate countries. The fieldwork depends largely on traditional methods, combined with the advantage of modern aids such as the Global Positioning System and radio communication. The information gained on the ground, followed up by modern laboratory and computing techniques in the UK, is being used to shed light on the sedimentological and structural evolution of this fascinating area.     

Two-colour photometric selection of high-redshift galaxies

In this paper we describe a set of models to predict the colours of galaxies over a wide range of redshifts. We present examples of output from the simulations, and discuss their application to the selection of galaxies at high redshifts, particularly through identification of the Lyman break. Additionally we consider the optimal choices of filters for selection at a range of redshifts.
An interface to a subset of the simulations has been made available on the World Wide Web for the benefit of the community at the location http://www-astro.physics.ox.ac.uk/~rejs/research/galcols.html/     

Waves in the solar photosphere

Time-sequences of line profile data have been subjected to a unique analysis which produces an amplitude and phase of the velocity and intensity at several line depths for each time sample and spatial point on the Sun. The data have been filtered to pass only the frequencies and spatial wavenumbers of the 5-min band. Yet, a secondary oscillation emerges, the phase of which propagates downward. Empirical eigenfunctions for velocity and intensity are given, and the kinetic energy flux is computed.Operated by the Association of Universities for Research in Astronomy under contract with the National Science Foundation.     

The Basel 1356 earthquake: which fault produced it?

The 1356 Basel earthquake was the strongest event to have shaken NW Europe in the last thousand years. The peculiar location of this historical event makes it possible to relate it to normal faulting along the edges of the Rhine Graben, as well as to reverse faulting along the Jura frontal thrust or to fault reactivation within the Hercynian basement. Alternate hypotheses are discussed and their implications compared taking into account available structural data and results of the morphotectonic study performed in the epicentral area. This study combines field observations with the analysis of SPOT satellite imagery, aerial photographs, and detailed topography. It is concluded that the Basel earthquake most probably reactivated a basement fault (reverse or wrench fault) beneath the shallow-depth aseismic detachment that underlies the Jura Mountains.     

Distribution of benthic foraminiferal assemblages in the transitional environment of the Djerba lagoon (Tunisia)

The eastern edge of the Djerba Island represents an important tourist pole. However, studies describing the environmental processes affecting this Island are scarce. Although never studied before, the peculiar Djerba lagoon is well known by the local population and by tourists. In July 2014, surface sediment and seawater samples were collected in this lagoon to measure grain size, organic matter content and living foraminiferal assemblages to describe environmental conditions. Seawater samples were also collected and the concentration of 17 chemical elements were measured by ICP-OES. The results show that a salinity gradient along the studied transect clearly impacts seagrass distribution, creating different environmental conditions inside the Djerba lagoon. Biotic and abiotic parameters reflect a transitional environment from hypersaline to normal marine conditions. Living benthic foraminifera show an adaptation to changing conditions within the different parts of the lagoon. In particular, the presence of Ammonia spp. and Haynesina depressula correlates with hypersaline waters, whilst Brizalina striatula characterizes the parts of the lagoon colonized by seagrass. Epifaunal species, such as Rosalina vilardeboana and Amphistegina spp. colonize hard substrata present at the transition between the lagoon and the open sea.