High-latitude magnetic fields and their time derivatives: interhemispheric similarities

There are two simple and objective measures of geomagnetic activity: the daily range of field components, and the daily maximum of the time derivative of the field. We study these using data from the geomagnetic latitude range of 50–85 deg, covering both the northern and southern hemispheres in 2003–2005. These activity indicators reach their maximum around the magnetic latitude of 70 deg. When comparing northern and southern sites of approximately equal geomagnetic latitudes, there are, in general, no striking interhemispheric differences.publishedVersio

Spatio-temporal development of large-scale auroral electrojet currents relative to substorm onsets

During auroral substorms, the electric currents flowing in the ionosphere change rapidly, and a large amount of energy is dissipated in the auroral ionosphere. An important part of the auroral current system is the auroral electrojets whose profiles can be estimated from magnetic field measurements from low-earth orbit satellites. In this paper, we combine electrojet data derived from the Swarm satellite mission of the European Space Agency with the substorm database derived from the SuperMAG ground magnetometer network data. We organize the electrojet data in relation to the location and time of the onset and obtain statistics for the development of the integrated current and latitudinal location for the auroral electrojets relative to the onset. The major features of the behaviour of the westward electrojet are found to be in accordance with earlier studies of field-aligned currents and ground magnetometer observations of substorm temporal statistics. In addition, we show that, after the onset, the latitudinal location of the maximum of the westward electrojet determined from Swarm satellite data is mostly located close to the SuperMAG onset latitude in the local time sector of the onset regardless of where the onset happens. We also show that the SuperMAG onset corresponds to a strengthening of the order of 100 kA in the amplitude of the median of the westward integrated current in the Swarm data from 15 min before to 15 min after the onset.Peer reviewe

The time derivative of the geomagnetic field has a short memory

Solar eruptions and other types of space weather effects can pose a hazard to the high voltage power grids via geomagnetically induced currents (GICs). In worst cases, they can even cause large-scale power outages. GICs are a complex phenomenon, closely related to the time derivative of the geomagnetic field. However, the behavior of the time derivative is chaotic and has proven to be tricky to predict. In our study, we look at the dynamics of the geomagnetic field during active space weather. We try to characterize the magnetic field behavior, to better understand the drivers behind strong GIC events. We use geomagnetic data from the IMAGE (International Monitor for Auroral Geomagnetic Effect) magnetometer network between 1996 and 2018. The measured geomagnetic field is primarily produced by currents in the ionosphere and magnetosphere, and secondarily by currents in the conducting ground. We use the separated magnetic field in our analysis. The separation of the field means that the measured magnetic field is computationally divided into external and internal parts corresponding to the ionospheric and telluric origin, respectively. We study the yearly directional distributions of the baseline subtracted, separated horizontal geomagnetic field, Delta H, and its time derivative, d Delta H/dt. The yearly distributions do not have a clear solar cycle dependency. The internal field distributions are more scattered than the external field. There are also clear, station-specific differences in the distributions related to sharp conductivity contrasts between continental and ocean regions or to inland conductivity anomalies. One of our main findings is that the direction of d Delta H/dt has a very short "reset time", around 2 min, but Delta H does not have this kind of behavior. These results hold true even with less active space weather conditions. We conclude that this result gives insight into the time scale of ionospheric current systems, which are the primary driver behind the time derivative's behavior. It also emphasizes a very short persistence of d Delta H/dt compared to Delta H, and highlights the challenges in forecasting d Delta H/dt (and GIC).Peer reviewe

Enteroatmospheric fistulae in open abdomen : Management and outcome – Single center experience

Background An enteroatmospheric fistula (EAF) is a known, morbid complication of open abdomen (OA) treatment. Patients with EAF often require repeated operations and long-lasting hospitalization. The goal is to reach prompt closure of both the fistula and the OA to avoid further morbidity and mortality. This study describes and analyzes the treatment of EAFs in our clinic and aims at clarifying the factors contributing to the outcome. Materials and Methods This study was carried out as a single-institution retrospective chart analysis of patients treated with an OA and EAF at our institute between years 2004 and 2014. Twenty-six patients were included in the analysis. Results Twenty-three (88%) of the EAFs were primarily managed surgically: 14 with suturing and 9 with resection and/or stoma. From the latter group two died 1 and 2 days, respectively, after surgery. Of the remaining 21 patients, EAF recurred in 12/14 (86%) patients after suturing whereas in only 3/7 (43%) patients after resection and/or stoma (p = 0.04). Among the 21 early survivors after EAF repair, four patients reached fascial closure simultaneously with the EAF repair. Of the rest 9/17 had Bogota bag or drapes as temporary abdominal closure and 8/17 were treated with vacuum assisted closure device with or without fascial traction by mesh. All the nine patients treated with non-negative pressure dressings developed recurrence but only 4/8 in the negative-pressure treated group (p < 0.02). All conservatively treated patients developed persistent EAF. The overall in-hospital mortality rate was 35% (9/26). Conclusion Surgical repair of EAF has a high failure rate. Primary resection of the affected region appears to be the most successful approach to avoid EAF recurrence. Furthermore, negative pressure wound therapy is superior to non-negative-pressure solutions in relation to EAF recurrence.Peer reviewe

Associating spatial patterns of zooplankton abundance with water temperature, depth, planktivorous fish and chlorophyll

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The European risk from geomagnetically induced currents (EURISGIC)

EURISGIC (www.eurisgic.eu) was the first continental-scale study of the geomagnetically induced current (GIC) hazard to Europe’s power transmission system. EURISGIC had a number of strands to it, including modelling GIC in the European system and understanding the possible extremes that the system could face. These project strands were represented by nine distinct work packages: • The construction of the first ever European power transmission grid model and an update of the existing UK model • The development of detailed conductivity models for Europe and, separately, the UK • The building of geomagnetic, GIC and related science databases • The production of a GIC risk map for Europe • The investigation of worst case scenarios and extremes in the grid models • The development of the NASA ‘Solar Shield’ magnetospheric and solar wind model for use in the European context • The enhancement of a prototype GIC and geomagnetic forecast system for Europe • The making of geomagnetic, geoelectric and GIC measurements to enhance our knowledge and validate models • The education of the public and other stakeholders through scientific papers and other materials. To assess and guide progress on the project a team of industry advisors was assembled. These advisors included senior power engineers from major electrical transmission system operators from across Europe, including National Grid in the UK. In this poster we demonstrate some of the major findings of the project. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no 260330