Multi-thousand member climate model simulations are highly valuable for showing characteristics of extreme weather events in historical and future climates. However, until now, studies using such a physically-based approach have been limited to using models with a resolution much coarser than the most modern systems. We have developed a global atmospheric model with ~60km resolution that can be run in the climateprediction.net distributed computing system to produce such large datasets. This resolution is finer than that of many current global climate models and sufficient for good simulation of extratropical synoptic features such as storms. It also allows many extratropical extreme weather events to be simulated without requiring regional downscaling. We will show that this model's simulation of extratropical winter weather is competitive with that in other state-of-the-art models. We will also present the first results generated by this system. One application has been the production of ~2000 member simulations based on sea surface temperatures in severe future winters produced in the UK Climate Projections 2018 dataset, generating large numbers of examples of plausible extreme wet and warm UK seasons. Another is showing the increasing spatial extent of precipitation extremes in the Northern Hemisphere extratropics.

Sudden Stratospheric Warmings (SSWs) are dramatic events where the usually-strong wind vortex around the edge of the polar stratosphere temporarily weakens or reverses, causing the polar temperature to rise by tens of Kelvin in just a few days. These events can trigger extreme winter weather outbreaks in Europe and North America, and are thus of significant scientific and practical interest. However, due to the major technical challenges involved in measuring wind from space, the changes in wind structure involved in an SSW have never been directly observed at the global scale, and our understanding of these changes has instead been developed through the use of point measurements, localised flight tracks and (primarily) computer models and assimilative analyses. Here, we exploit novel measurements from Aeolus, the first satellite capable of observing wind in the upper troposphere and lower stratosphere, to study this process observationally during the major January 2021 SSW. As the event is still ongoing at time of abstract submission, precise details of the changes seen in Aeolus data over the full event cannot be provided; however, data from the first full week of the SSW shows clear observational evidence in Aeolus data of significant and descending-with-time structural changes to the lower stratospheric flow, including reversal of the mean zonal flow, a clear shifting of the vortex centre to a location over northern Russia, and perhaps early evidence of a developing split of the vortex into two sub-vortices.

Introduction. In August 2015, northeast Africa and the Middle East experienced a heat wave that caused high levels of human discomfort, even for countries particularly adapted to extreme heat. Reports suggest that more than 90 people died throughout Egypt, with the majority being elderly (Al Jazeera, 17 August 2015). In and around Cairo, many of the deaths were blamed on overpopulation and cramped living conditions, notably including prisons and psychiatric centers, a problem that is not necessarily restricted to the developing world (Huffington Post, 15 August 2015; Holt 2015). The local health ministry reported that persistently high humidity was at least partially to blame. In the previous year (2014), the region experienced an unprecedented drought (Bergaoui et al. 2015; Barlow and Hoell 2015), and combined with political tensions, the recent heat wave could enhance unrest in the region (Schleussner et al. 2016). While direct attribution of climate change on mortality is possible (Mitchell et al. 2016a), the required observed mortality data are not easily obtained in this specif ic region. As such, the attribution study is performed on the wet bulb globe temperature (WBGT), a proxy for human discomfort. Note that Mitchell et al. (2016a) used a different heat stress metric, apparent temperature, because this could be used directly with the health impact assessment (HIA) model they employed. As this study does not use a HIA model, the WBGT is chosen so the study can be contrasted with a recent climate predictions study (Pal and Eltahir 2015). A comparison of the two different heat stress metrics is given in Willett and Sherwood (2012). Methods. The WBGT is estimated using the following equation (Fischer and Knutti 2012): WBGT = 0.567T + 0.393e + 3.94 The water vapor pressure, e = f(T, RH), can be approximated using a derivation of the Magnus formula (Sonntag 1990; Sippel and Otto 2014), where the terms T and RH are temperature and relative humidity, respectively, and are available from model output and from the Met Office Integrated Data Archive System (MIDAS; Met Office 2012) station data. This study focuses on Egypt as a whole, but a subanalysis is also performed for Cairo (the most populated city in Egypt). A map of the station locations is given in Fig. 14.1a with Cairo marked in red. Event attribution is performed using the weather@ home framework, which comprises a global atmosphere-only driving model (HadAM3P; Massey et al. 2015) and a 50-km regional model covering northern Africa and the Middle East (the setup is identical to Bergaoui et al. 2015). Approximately 2000 simulations of 2015 are run using perturbed initial conditions (actual scenario) and compared with ~2000 simulations estimating a naturalized version of 2015 (natural scenario). The natural simulations employ solar and volcanic forcings fixed at 2015 levels with all other forcings set to preindustrial values. However, the actual scenarios employ all forcings at 2015 levels, which include the aforementioned natural forcings as well as greenhouse gases, aerosols, and land use. The model is spun up for 2 years before 2015 to equilibrate long-memory processes in the Earth–atmosphere system. The natural scenario simulations include 10 estimates of possible natural sea surface temperatures (SSTs), which are estimated using coupled ocean– atmosphere models (Schaller et al. 2016). The model simulations are interpolated to each of the different station locations.

Abstract Background In 1999 an emergency vascular service for Bristol and Avon (including Weston-Super-Mare) (population approximately 1 million) was initiated. Methods Collaboration between Bristol Royal Infirmary, Frenchay and Southmead Hospitals provides week-on–week-off vascular cover for patients requiring urgent and emergency interventions within 24 h. The rota accommodates National Confidential Enquiry into Perioperative Deaths and Vascular Surgical Society of Great Britain and Ireland recommendations, governance issues, and enhances emergency vascular care for Avon residents. Prospectively collected data for the first year (May 1999 to April 2000) are reviewed. Results There were 289 emergency admissions. (In-hospital referrals were not transferred but contributed up to 40 per cent of the extra emergency workload per unit.) Referrals were also accepted from seven Trusts outside the designated catchment area. Caseload included 86 patients with a ruptured or acutely symptomatic aortic aneurysm, of whom 69 underwent operation (30 per cent mortality rate); 17 patients were not operated on. Some 136 patients had critical leg ischaemia (43 acute, 93 chronic); angiography or duplex ultrasonography was performed in 105 cases (77 per cent); 39 patients (29 per cent) had undergone previous intervention for peripheral vascular disease; the mortality rate was 18 (13 per cent) of 136; 18 (13 per cent) of 136 patients required an amputation. Other cases included: upper limb ischaemia, 20 (7 per cent); paediatric emergency, seven (2 per cent); symptomatic carotid disease, five (2 per cent; four endarterectomies with no death or stroke). Some 5 per cent of referrals were inappropriate (venous ulcer, spinal stenosis, etc.). No outcomes were compromised by interhospital transfers. Vascular surgeons operated on nine high-risk patients away from their ‘base’ hospital. A consultant was the principal or assistant operator in more than 95 per cent of operations but, despite trainee rota adjustments, a designated vascular trainee was present in only about 40 per cent of cases. Conclusion Interhospital provision of emergency vascular services for a large population is feasible, does not compromise quality of care, and regulates emergency workload. Further attention to training issues is indicated.

First Name is required invalid characters Last Name is required invalid characters Email Address is required Invalid Email Address Invalid Email Address

Based on experimental observations and theoretical predictions, the authors describe the influence of prestressing on the torsional response of concrete beams. A series of six beams were tested all with the same amount of hoop reinforcement but with varying amounts of longitudinal steel. The theoretical predictions of the compression field theory are compared with Zia and McGee's design equations and with the experimental results.