Multi-instrument ground-based observations of a travelling convection vortices event

A coordinated ground-based observational campaign using the IMAGE magnetometer network, EISCAT radars and optical instruments on Svalbard has made possible detailed studies of a travelling convection vortices (TCV) event on 6 January 1992. Combining the data from these facilities allows us to draw a very detailed picture of the features and dynamics of this TCV event. On the way from the noon to the drawn meridian, the vortices went through a remarkable development. The propagation velocity in the ionosphere increased from 2.5 to 7.4 km s−1, and the orientation of the major axes of the vortices rotated from being almost parallel to the magnetic meridian near noon to essentially perpendicular at dawn. By combining electric fields obtained by EISCAT and ionospheric currents deduced from magnetic field recordings, conductivities associated with the vortices could be estimated. Contrary to expectations we found higher conductivities below the downward field aligned current (FAC) filament than below the upward directed. Unexpected results also emerged from the optical observations. For most of the time there were no discrete aurora at 557.7 nm associated with the TCVs. Only once did a discrete form appear at the foot of the upward FAC. This aurora subsequently expanded eastward and westward leaving its centre at the same longitude while the TCV continued to travel westward. Also we try to identify the source regions of TCVs in the magnetosphere and discuss possible generation mechanisms.

The statistical cusp: a flux transfer event model

Traditionally, the cusp has been described in terms of a time-stationary feature of the magnetosphere which allows access of magnetosheath-like plasma to low altitudes. Statistical surveys of data from low-altitude spacecraft have shown the average characteristics and position of the cusp. Recently, however, it has been suggested that the ionospheric footprint of flux transfer events (FTEs) may be identified as variations of the “cusp” on timescales of a few minutes. In this model, the cusp can vary in form between a steady-state feature in one limit and a series of discrete ionospheric FTE signatures in the other limit. If this time-dependent cusp scenario is correct, then the signatures of the transient reconnection events must be able, on average, to reproduce the statistical cusp occurrence previously determined from the satellite observations. In this paper, we predict the precipitation signatures which are associated with transient magnetopause reconnection, following recent observations of the dependence of dayside ionospheric convection on the orientation of the IMF. We then employ a simple model of the longitudinal motion of FTE signatures to show how such events can easily reproduce the local time distribution of cusp occurrence probabilities, as observed by low-altitude satellites. This is true even in the limit where the cusp is a series of discrete events. Furthermore, we investigate the existence of double cusp patches predicted by the simple model and show how these events may be identified in the data.

The role of statistical learning in the acquisition of motion event construal in a second language

Learning to talk about motion in a second language is very difficult because it involves restructuring deeply entrenched patterns from the first language (Slobin 1996). In this paper we argue that statistical learning (Saffran et al. 1997) can explain why L2 learners are only partially successful in restructuring their second language grammars. We explore to what extent L2 learners make use of two mechanisms of statistical learning, entrenchment and pre-emption (Boyd and Goldberg 2011) to acquire target-like expressions of motion and retreat from overgeneralisation in this domain. Paying attention to the frequency of existing patterns in the input can help learners to adjust the frequency with which they use path and manner verbs in French but is insufficient to acquire the boundary crossing constraint (Slobin and Hoiting 1994) and learn what not to say. We also look at the role of language proficiency and exposure to French in explaining the findings.

Rapid changes in the redox conditions of the western Tethys Ocean during the early Aptian oceanic anoxic event

The early Aptian (125 to 121 Ma) records an episode of severe environmental change including a major perturbation of the carbon cycle, an oceanic anoxic event (OAE 1a, 122.5 Ma), a platform drowning episode and a biocalcification crisis. We propose to trace changes in the oxygenation state of the ocean during the early Aptian anoxic event using the redox-sensitive trace-element (RSTE) distribution, phosphorus accumulation rates (PARs) and organic-matter characterization in three different basins of the western Tethys. The following sections have been investigated: Gorgo a Cerbara (central Italy) in the Umbria Marche basin, Glaise (SE France) in the Vocontian basin and Cassis/La Bédoule (SE France) located in the Provencal basin. In the Gorgo a Cerbara section, RSTE distributions show a low background level along the main part of the section, contrasted by different maxima in concentrations within the Selli level. In the Glaise section, the Goguel level displays a weak increase in RSTE contents coeval with moderate TOC values. At Cassis/La Bédoule, no significant RSTE enrichments have been observed in sediments equivalent to the Selli level. These differences in the records of the geochemical proxies of the Selli level or its equivalent indicate the deposition under different redox conditions, probably related to the paleogeography. Our data indicate the development of anoxic–euxinic conditions in the deeper part of the Tethys during OAE 1a, whereas in the shallower environments, conditions were less reducing. Moreover, at Gorgo a Cerbara, the Selli level is characterized by rapid changes in the intensity of reducing conditions in the water column. Ocean eutrophication seems to be a major factor in the development and the persistence of anoxia as suggested by the PAR evolution. Higher PAR values at the onset of OAE 1a suggest an increase in nutrient input, whereas the return to lower values through the first part of the OAE 1a interval may be related to the weakened capacity to retain P in the sedimentary reservoir due to bottom-water oxygen depletion. This general pattern is contrasted by the data of Gorgo a Cerbara, where the sediments deposited during the OAE 1a interval show P-enrichments (mainly authigenic P). This is associated with maxima in TOC values and Corg:Ptot ratios, suggesting that a part of the remobilized P was trapped in the sediments and as such prevented from returning to the water column.

Implications of event attribution for loss and damage policy

The United Nations Framework Convention on Climate Change (UNFCCC) has established the Warsaw International Mechanism (WIM) to deal with loss and damage associated with climate change impacts, including extreme events, in developing countries. It is not yet known whether events will need to be attributed to anthropogenic climate change to be considered under the WIM. Attribution is possible for some extreme events- a climate model assessment can estimate how greenhouse gas emissions have affected the likelihood of their occurrence. Dialogue between scientists and stakeholders is required to establish whether, and how, this science could play a role in the WIM.

The expression of the Cenomanian-Turonian oceanic anoxic event in Tibet

The Gongzha section of Tibet, China is located at the northern margin of the Indian Plate (SE Tethys) and is characterized by hemipelagic grey marls and marly limestones, light grey limestones and silty limestones, but no organic-rich sediments. High-resolution biostratigraphy reveals an expanded Cenomanian–Turonian (CT) boundary interval and the δ13C record includes the main features of the classical positive carbon-isotope excursion that characterizes the CT oceanic anoxic event. The biotic response inferred from the foraminifera suggests that oxic to dysoxic conditions prevailed, except for a short interval marked by peak abundance of Heterohelix that indicates a significantly dysoxic environment during the δ13C “b” peak excursion. The overall decreasing trend in redox-sensitive trace elements (RSTE) during the maximum δ13C excursion confirms the absence of significant longer-lasting anoxia in the Gongzha section. Enrichments in RSTE are linked to phases of increased detrital input. Chemical weathering indices suggest that the upper Cenomanian sediments accumulated under an increasingly hot and humid climate that culminated near the CT boundary. In the early Turonian lower weathering indices suggest a warm, drier climatic regime with reduced continental runoff. Phosphorus mass-accumulation rates show a significant peak at the onset of the positive δ13C excursion, followed by a decrease up to the basal Turonian. This pattern is positively correlated with the long-term decrease in detrital index as also observed in numerous other CT boundary sections (e.g., Eastbourne, Pueblo, and Whadi El Ghaib, Sinaï). Long-term phosphorus accumulation in the Gongzha section is therefore associated with changes in detrital input. The overall decreased detrital input can be explained by the increasingly remote continental sources due to the major transgression at the end of Cenomanian, coupled with changes in continental weathering intensity linked to increasingly more arid climate conditions.

Second language influence on first language motion event encoding and categorization in Spanish-speaking children learning L2 English

Studies show cross-linguistic differences in motion event encoding, such that English speakers preferentially encode manner of motion more than Spanish speakers, who preferentially encode path of motion. Focusing on native Spanish speaking children (aged 5;00-9;00) learning L2 English, we studied path and manner verb preferences during descriptions of motion stimuli, and tested the linguistic relativity hypothesis by investigating categorization preferences in a non-verbal similarity judgement task of motion clip triads. Results revealed L2 influence on L1 motion event encoding, such that bilinguals used more manner verbs and fewer path verbs in their L1, under the influence of English. We found no effects of linguistic structure on non-verbal similarity judgements, and demonstrate for the first time effects of L2 on L1 lexicalization in child L2 learners in the domain of motion events. This pattern of verbal behaviour supports theories of bilingual semantic representation that postulate a merged lexico-semantic system in early bilinguals.

Stakeholder perceptions of event attribution in the loss and damage debate

In 2013 the Warsaw International Mechanism (WIM) for loss and damage (L&D) associated with climate change impacts was established under the United Nations Framework Convention on Climate Change (UNFCCC). For scientists, L&D raises ques- tions around the extent that such impacts can be attributed to anthropogenic climate change, which may generate complex results and be controversial in the policy arena. This is particularly true in the case of probabilistic event attribution (PEA) science, a new and rapidly evolving field that assesses whether changes in the probabilities of extreme events are attributable to GHG emissions. If the potential applications of PEA are to be considered responsibly, dialogue between scientists and policy makers is fundamental. Two key questions are considered here through a literature review and key stakeholder interviews with representatives from the science and policy sectors underpinning L&D. These provided the opportunity for in-depth insights into stakeholders’ views on firstly, how much is known and understood about PEA by those associated with the L&D debate? Secondly, how might PEA inform L&D and wider climate policy? Results show debate within the climate science community, and limited understanding among other stakeholders, around the sense in which extreme events can be attributed to climate change. However, stake- holders do identify and discuss potential uses for PEA in the WIM and wider policy, but it remains difficult to explore precise applications given the ambiguity surrounding L&D. This implies a need for stakeholders to develop greater understandings of alternative conceptions of L&D and the role of science, and also identify how PEA can best be used to support policy, and address associated challenges.

Buckets, baskets and boots: exhibition event at MERL

Launch event part of Universities Week on Monday 9th Co-researchers from Reading College Learners with Learning Difficulties/Disabilities dept will present their Sensory Objects research in the Museum of English Rural Life (MERL)

Towards expressive rule induction on IP network event streams

In order to gain insights into events and issues that may cause errors and outages in parts of IP networks, intelligent methods that capture and express causal relationships online (in real-time) are needed. Whereas generalised rule induction has been explored for non-streaming data applications, its application and adaptation on streaming data is mostly undeveloped or based on periodic and ad-hoc training with batch algorithms. Some association rule mining approaches for streaming data do exist, however, they can only express binary causal relationships. This paper presents the ongoing work on Online Generalised Rule Induction (OGRI) in order to create expressive and adaptive rule sets real-time that can be applied to a broad range of applications, including network telemetry data streams.

A common framework for approaches to extreme event attribution

The extent to which a given extreme weather or climate event is attributable to anthropogenic climate change is a question of considerable public interest. From a scientific perspective, the question can be framed in various ways, and the answer depends very much on the framing. One such framing is a risk-based approach, which answers the question probabilistically, in terms of a change in likelihood of a class of event similar to the one in question, and natural variability is treated as noise. A rather different framing is a storyline approach, which examines the role of the various factors contributing to the event as it unfolded, including the anomalous aspects of natural variability, and answers the question deterministically. It is argued that these two apparently irreconcilable approaches can be viewed within a common framework, where the most useful level of conditioning will depend on the question being asked and the uncertainties involved.

The impact of the abrupt 8.2 ka cold event on the Mesolithic population of western Scotland: a Bayesian chronological analysis using ‘activity events’ as a population proxy

The potential impact of the abrupt 8.2 ka cold event on human demography, settlement patterns and culture in Europe and the Near East has emerged as a key theme in current discussion and debate. We test whether this event had an impact on the Mesolithic population of western Scotland, a case study located within the North Atlantic region where the environmental impact of the 8.2 ka event is likely to have been the most severe. By undertaking a Bayesian analysis of the radiocarbon record and using the number of activity events as a proxy for the size of the human population, we find evidence for a dramatic reduction in the Mesolithic population synchronous with the 8.2 ka event. We interpret this as reflecting the demographic collapse of a low density population that lacked the capability to adapt to the rapid onset of new environmental conditions. This impact of the 8.2 ka event in the North Atlantic region lends credence to the possibility of a similar impact on populations in Continental Europe and the Near East.