Ionospheric response to the corotating interaction region-driven geomagnetic storm of October 2002

Unlike the geomagnetic storms produced by coronal mass ejections (CMEs), the storms generated by corotating interaction regions (CIRs) are not manifested by dramatic enhancements of the ring current. The CIR-driven storms are however capable of producing other phenomena typical for the magnetic storms such as relativistic particle acceleration, enhanced magnetospheric convection and ionospheric heating. This paper examines ionospheric plasma anomalies produced by a CIR-driven storm in the middle- and high-latitude ionosphere with a specific focus on the polar cap region. The moderate magnetic storm which took place on 14–17 October 2002 has been used as an example of the CIR-driven event. Four-dimensional tomographic reconstructions of the ionospheric plasma density using measurements of the total electron content along ray paths of GPS signals allow us to reveal the large-scale structure of storm-induced ionospheric anomalies. The tomographic reconstructions are compared with the data obtained by digital ionosonde located at Eureka station near the geomagnetic north pole. The morphology and dynamics of the observed ionospheric anomalies is compared qualitatively to the ionospheric anomalies produced by major CME-driven storms. It is demonstrated that the CIR-driven storm of October 2002 was able to produce ionospheric anomalies comparable to those produced by CME-driven storms of much greater Dst magnitude. This study represents an important step in linking the tomographic GPS reconstructions with the data from ground-based network of digital ionosondes

Mapping plasma structures in the high-latitude ionosphere using beacon satellite, incoherent scatter radar and ground-based magnetometer observations

In the autumn of the year 2000, four radio receivers capable of tracking various beacon satellites were set up along the southwestern coast of Greenland. They are used to reconstruct images of the ionospheric plasma density distribution via the tomographic method. In order to test and validate tomographic imaging under the highly variable conditions often prevailing in the high-latitude ionosphere, a time interval was selected when the Sondrestrom incoherent scatter radar conducted measurements of the ionospheric plasma density while the radio receivers tracked a number of beacon satellites. A comparison between two-dimensional images of the plasma density distribution obtained from the radar and the satellite receivers revealed generally good agreement between radar measurements and tomographic images. Observed discrepancies can be attributed to F region plasma patches moving through the field of view with a speed of several hundred meters per second, thereby smearing out the tomographic image. A notable mismatch occurred around local magnetic midnight when a magnetospheric substorm breakup occurred in the vicinity of southwest Greenland (identified from ground-based magnetometer observations). The breakup was associated with a sudden intensification of the westward auroral electrojet which was centered at about 69 and extended up to some 73 corrected geomagnetic latitude. Ground-based magnetometer data may thus have the potential of indicating when the tomographic method is at risk and may fail. We finally outline the application of tomographic imaging, when combined with magnetic field data, to estimate ionospheric Joule heating rates

Impact of the ‘Contributing Factors in Construction Accidents’ (ConCA) model

In 2005 the ‘Contributing factors in Construction Accidents’ framework (ConCA) introduced a sociotechnical systems approach to risk management in construction. ConCA demonstrated the value of exploring distal factors and identifying underlying or latent causes: It promoted an understanding of construction accidents as systemic accidents and challenged an industry-wide culture of blaming frontline workers. A decade later the original article has been cited by research from 37 countries, shaping inquiries and initiatives to improve safety in both the UK and Australia. But to what extent has systems thinking infiltrated practitioners and policy-makers’ views? Despite broader views of contributing factors, many practitioners still view workers in a negative light, holding them responsible for accidents because of complacency, cynicism about safety, or a high-tolerance for risk. This paper evaluates the impact of the ConCA framework, updates it, and develops our understanding of the relationships between immediate circumstances and distal factors, as seen by an expert panel of participants (n = 32). A more in-depth ‘ConCA+’ framework is proposed. It challenges the negative perceptions of workers, and supports shifting the emphasis of risk management away from worker behaviors and towards resolving wider systemic issues. New directions are proposed which show how knowledge management, job design, technological innovation, empowerment and collaboration should be the focus of future work

Radio tomographic imaging of sporadic-E layers during SEEK-2

During the SEEK-2 Rocket Campaign in August 2002, a Dual Band Beacon (DBB) transmitting to Ground Receivers provided unique data on E-Region electron densities. Information from two rocket beacons and four ground receivers yielded multiple samples of E-region horizontal and vertical variations. The radio beacon measurements were made at four sites (Uchinoura, Tarumizu, Tanegashima, Takazaki) in Japan for two rockets (S310-31 and S310-32) launched by the Institute of Space and Aeronautical Science (ISAS). Analysis was completed for four sets of beacon data to provide electron density images of sporadic-E layers. Signals from the two-frequency beacons on the SEEK-2 rockets were processed to yield total electron content (TEC) data that was converted into electron density measurements. Wide variations in layer structures were detected. These included horizontal sporadic-E variations, vertical profiles of double, single, and weak layers. The radio beacon measurements were shown to be in agreement with the in-situ SEEK-2 sensors. The first tomographic image of a sporadic-E layer was produced from the data. The rocket beacon technique was shown to be an excellent tool to study sporadic-E layers because absolute TEC accuracy of 0.01 TEC Units can be easily obtained and, with proper receiver placement, electron density images can be produced using computerized ionospheric tomography with better than 1km horizontal and vertical resolution

An interhemispheric comparison of GPS phase scintillation with auroral emission observed at the South Pole and from the DMSP satellite

The global positioning system (GPS) phase scintillation caused by highlatitude ionospheric irregularities during an intense high-speed stream (HSS) of the solar wind from April 29 to May 5, 2011, was observed using arrays of GPS ionospheric scintillation and total electron content monitors in the Arctic and Antarctica. The one-minute phase-scintillation index derived from the data sampled at 50 Hz was complemented by a proxy index (delta phase rate) obtained from 1-Hz GPS data. The scintillation occurrence coincided with the aurora borealis and aurora australis observed by an all-sky imager at the South Pole, and by special sensor ultraviolet scanning imagers on board satellites of the Defense Meteorological Satellites Program. The South Pole (SP) station is approximately conjugate with two Canadian High Arctic Ionospheric Network stations on Baffin Island, Canada, which provided the opportunity to study magnetic conjugacy of scintillation with support of riometers and magnetometers. The GPS ionospheric pierce points were mapped at their actual or conjugate locations, along with the auroral emission over the South Pole, assuming an altitude of 120 km. As the aurora brightened and/or drifted across the field of view of the all-sky imager, sequences of scintillation events were observed that indicated conjugate auroras as a locator of simultaneous or delayed bipolar scintillation events. In spite of the greater scintillation intensity in the auroral oval, where phase scintillation sometimes exceeded 1 radian during the auroral break-up and substorms, the percentage occurrence of moderate scintillation was highest in the cusp. Interhemispheric comparisons of bipolar scintillation maps show that the scintillation occurrence is significantly higher in the southern cusp and polar cap

Managing construction health and safety: Migrant workers and communicating safety messages

The economic prosperity of individual countries around the world has fuelled the transportation of migrant workers for centuries. The phenomenon of globalisation and with it cheaper and quicker forms of international travel has transformed the nature of migrant worker involvement in construction projects. For example, Irish 'navvies' have traditionally made up a large percentage of the UK construction workforce. However, political changes in the neighbouring Republic of Ireland leading to an economic boom have kept native workers at home. This gap in the UK workforce has coincided with all expansion of the European Union and there has been all influx of Polish, Lithuanian and other A8 ascension countries' nationals. The change, over a relatively short period of time, less than 10 years, has put pressure oil the management of health and safety at a time when the UK construction industry was progressing from relative successes in tackling safety issues to dealing with the health of construction workers. The challenge of converting the health and safety systems to accommodate a multi national/cultural workforce is being addressed using initiatives such as, translation of health and safety materials, use of interpreters and an increased use of visual methods for communicating health and safety messages. There is little scientific evidence to support the effectiveness of these initiatives and investigations into these methods and the affects of the migrant workforce on health and safety are proposed