This work presents a feasibility study of utilizing Health Canada's terrestrial radiation monitoring network, the Fixed Point Surveil-lance (FPS) network, for space weather monitoring through demonstrating detections of Forbush decrease and ground level enhance-ment events. The network is currently comprised of more than eighty sodium iodide spectrometers distributed across Canada. It was designed for terrestrial radiation monitoring but is also capable of registering cosmic radiation in a high-energy channel. Data from four-teen FPS stations for the period from 2003 to 2018 were analyzed and compared with data obtained by other ground-level cosmic radi-ation monitoring systems. The level of atmospheric impacts on measurements can be well explained, and signatures of both long-term solar cycle variations and sporadic solar events have been detected in the FPS network. The Forbush decrease amplitudes in FPS were found to be comparable to those obtained in the global muon detector network but about 2-3 times lower than those recorded by the global neutron monitoring network. This study suggests that the 20 years of cosmic ray data from the FPS network can be used for cli-matological space weather studies. In addition, the network can be readily available for real-time space weather monitoring. Crown Copyright (c) 2023 Published by Elsevier B.V. on behalf of COSPAR. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

Telluric currents are the natural phenomena especially pronounced in the high latitude areas (above 60 degrees). These currents, as any stray current, are able to interfere with pipeline cathodic protection systems, and came into wide consideration with construction of pipelines in northern areas, where the geomagnetic variations are more severe and last for prolonged times.The paper will explain the approach developed for estimation of pipeline corrosion rates due to telluric activity, and results of its applications.Statistical evaluation of the occurrence rates for the pipe-to-soil potential difference values based on modelling of the pipeline response to the geomagnetic activity in two different locations (high latitude and mid-latitude) will be combined with the method developed for calculation of corrosion rate (metal loss). The presented approach and results of its application to different types of pipelines located at different latitudes can be used as a practical guidance for the assessments of the space weather impacts on pipeline operations.

Continuous observation of polar regions from space remains an important unsolved technical challenge of great interest for the international meteorological community. This capacity would allow achieving global continuous coverage once combined with the geostationary (GEO) satellite network. From a practical point of view, continuous coverage of polar regions with a small number of spacecraft can be obtained from a constellation of satellites either in highly elliptical orbits (HEO) or in medium Earth orbits (MEO). The study compares HEO and MEO satellite constellations for their capacity to provide continuous imaging of polar regions as function of the viewing zenith angle (VZA) and evaluates the corresponding latitude limits that ensure sufficient overlap with GEO imagery. Earlier studies assumed the latitude boundary of 60 degrees and the VZA range 70 degrees-85 degrees depending on the space mission focus: meteorological purposes or communications. From the detailed analysis of meteorological retrieval requirements, this study suggests that the overlap of the GEO and polar observing systems (HEO or MEO) should occur down to the latitude band 45 degrees-50 degrees with a maximum VZA ranging between 60 degrees and 64 degrees. This coverage requirement can be met with two sets of three-satellite HEO constellations (one for each polar area) or a six-satellite MEO constellation. The 12-h Molniya and 14-, 15-, and 16-h HEO systems have been analyzed and determined to meet these revised requirements. The study demonstrates that the six-satellite 24-h MEO system can provide a suitable solution, which is also beneficial from the point of view of ionizing radiation and image acquisition geometry. Among the HEO systems, the 16-h HEO has some advantages relative to other HEO systems from the point of view of spatial coverage and space radiation.

The study reports results of analysis related to minimization of the total ionizing dose (TID) for the Multiple Apogee Highly Elliptical Orbit with periods 14 h, 15 h and 16 h introduced earlier for continuous observation of the Earth's polar regions. The modeling of space environment has been conducted with use of the European Space Agency's SPENVIS tool based on the AE8/AP8 radiation models. Originally, the set of orbital parameters has been derived through the optimization process that included among other factors criteria for the apogee height limit and minimization of the radiation dose caused by trapped protons. By relaxing the apogee altitude limit, this study found the total ionizing dose TID can be significantly reduced for 15-h and 16-h orbits, while the originally proposed 14-h orbit is already at the minimum of radiation dose. For 15-h and 16-h orbits this converts into reduction of the thickness of aluminum shielding by factor 1.24-1.28 or an equivalent increase in the mission lifetime by up to 8.1 years. For example, an increase in apogee altitude to 49,620 km for 16-h orbit (eccentricity e = 0.74) in comparison to the originally proposed 16-h orbit (altitude equal to 43,500 km, e = 0.55) reduces the TID so that the shielding thickness decreases to 3.53 mm, instead of 4.35 mm of aluminum slab for the same 15-year duration of mission. Decrease of the TID is achieved due to significant reduction of ionizing radiation from the trapped electrons through the better placing of the orbit trajectory in the slot area, but at the expense of slight increase of ionizing radiation from the trapped protons and increase in apogee altitude to 46,640 km and 49,620 km for 15-h and 16-h orbit, correspondingly. Crown Copyright (C) 2019 Published by Elsevier Ltd on behalf of COSPAR.

Studies of Alternating Current (AC) interference on pipelines from nearby power lines usually consider the fundamental (50Hz or 60Hz) frequency of the power line currents. However, these currents can also contain considerable harmonics of the fundamental AC frequency. Measurements on pipelines in Canada and Sweden have shown that these harmonics can produce significant interference in the pipe-to-soil potentials. The electromagnetic fields experienced by the pipeline are dependent on three types of parameters. The first is associated with the phase relations of the power line harmonics, classified as ‘positive sequence’, ‘negative sequence’, and ‘zero sequence’. The second is related to the conductivity of the host media (ground) that affects the electromagnetic field experienced by a pipeline. The third is pipeline series impedance and parallel admittance, which introduces additional frequency dependence. This paper examines the frequency dependence of the phase relation of the power line currents, the Earth response, and the pipeline response and shows how they can be combined to provide an AC risk assessment.

Power transmission lines above the ground, cables and pipelines in the ground and under the sea, and in general all man-made long grounded conductors are exposed to the variations of the natural electromagnetic field. The resulting currents in the networks (commonly named geomagnetically induced currents, GIC), are produced by the conductive and/or inductive coupling and can compromise or even disrupt system operations and, in extreme cases, cause power blackouts, railway signalling mis-operation, or interfere with pipeline corrosion protection systems. To properly model the GIC in order to mitigate their impacts it is necessary to know the frequency dependence of the response of these systems to the geomagnetic variations which naturally span a wide frequency range. For that, the general equations of the electromagnetic induction in a multi-layered infinitely long cylinder (representing cable, power line wire, rail or pipeline) embedded in uniform media have been solved utilising methods widely used in geophysics. The derived electromagnetic fields and currents include the effects of the electromagnetic properties of each layer and of the different types of the surrounding media. This exact solution then has been used to examine the electromagnetic response of particular samples of long conducting structures to the external electromagnetic wave for a wide range of frequencies. Because the exact solution has a rather complicated structure, simple approximate analytical formulas have been proposed, analysed and compared with the results from the exact model. These approximate formulas show good coincidence in the frequency range spanning from geomagnetic storms (less than mHz) to pulsations (mHz to Hz) to atmospherics (kHz) and above, and can be recommended for use in space weather applications.

In pipelines, telluric currents are responsible for variations in pipe-to-soil potentials (PSP) that interfere with pipeline surveys and might contribute to pipeline corrosion. This chapter provides a review of the literature on pipeline-telluric interference. It explains the geomagnetic sources of telluric activity, the impacts of earth's deep conductivity structures, pipeline's response to telluric electric fields and the methodology for assessing telluric effects, and mitigation/compensation of telluric effects. The geomagnetic field variations that produce telluric activity have their origin with processes on the Sun. The telluric electric fields produced by geomagnetic field variations will drive telluric currents along a pipeline, as well as in the ground. The size of telluric PSP variations produced during geomagnetic disturbance depends on the amplitude of the geomagnetic field variations, the conductivity structure of the earth, and the pipeline response. The chapter examines the knowledge gaps and open questions about telluric effects.

A novel type of multiple-apogee highly elliptical orbits termed as MAP HEO with a period of rotation between 14 h and 15 h is introduced. These orbits are designed to achieve continuous geostationary (GEO)-like imaging of the polar regions in an optimum way. The combination of GEO and HEO satellites would then offer continuous monitoring of weather from space at any point of the globe. This capacity would represent a breakthrough for short- and long-term weather forecasting and narrowing uncertainties in the knowledge of the Earth's climate through better sampling and more accurate characterization of the diurnal cycle. MAP HEO systems can be launched at critical inclination and are characterized by a local minimum of ionizing radiation. These features simplify the process of orbit maintenance, reduce radiation shielding requirements, and favor a longer lifetime of the mission. Unlike previously considered HEO systems implemented for communications, such as 12-h Molniya and 24-h Sirius radio systems, a MAP HEO constellation achieves a uniform geometrical sampling, which reduces view angle dependent biases. These observational conditions with complete coverage of the diurnal cycle, diverse range of solar illumination, and viewing observational conditions are beneficial for high-latitude meteorological and climate applications, such as the retrieval of Essential Climate Variables (ECV).

The ionizing radiation environment was analyzed for a variety of potential Highly Elliptical Orbits (HEOs) with orbital periods ranging from 6 h to 24 h suitable to continuously monitor the Arctic region. Several models available from the ESA Space Environment Information System (SPENVIS) online tool were employed, including the new-generation AE9/AP9 model for trapped radiation. Results showed that the Total Ionizing Dose (TID) has a well-pronounced local minimum for the 14-h orbit, which is nearly identical to the overall minimum observed for the longest orbital period (24 h). The thickness of slab aluminum shielding required to keep the annual TID below 10, 5 and 3.33 krad (i.e. 150, 75 and 50 krad for 15 years of mission duration) for a 14-h orbit is 2.1, 2.7 and 3.1 mm respectively. The 16-h orbit requires an additional 0.5 mm of aluminum to achieve the same results, while the 24-h orbit requires less shielding in the order of 0.2-0.3 mm. Comparison between the AE8/AP8 and AE9/AP9 models was conducted for all selected orbits. Results demonstrated that differences ranged from -70% to +170% depending on orbit geometry.The vulnerability to the Single Event Effect (SEE) was compared for all orbits by modeling the Linear Energy Transfer (LET) for long-term conditions and for the 5 min "worst case" scenario. The analysis showed no preference among orbits with periods longer than 15 h, and in order to keep the 14-h orbit at the same level, the shielding should be increased by similar to 33% or approximately by 1 mm. To keep the Single Event Upset (SEU) rate produced by the "worst case" event at the same order of magnitude as for the "statistical" long-term case, the thickness of aluminum should be as high as 22 mm. The overall conclusion from a space environment point of view is that all HEO orbits with periods equal to or longer than 14 h can be regarded as good candidates for operational missions. Therefore, selection of orbit should be based on other criteria, for example, uniformity of spatial coverage for meteorological imaging or the configuration of the ground network for data reception. Crown copyright (C) 2014 Published by Elsevier Ltd. on behalf of COSPAR.

We report on the development of numerical components for an operational solar wind prediction framework. In particular, we discuss the coronal magnetic field component based on the potential field source surface and Schatten current sheet models, and the solar wind speed component which uses the empirical Wang-Sheeley-Arge relation between solar wind speed and open magnetic field lines. Using synoptic maps of photospheric fields in a stand-alone operational mode, the components provide the configuration of the global coronal magnetic field and prediction of the solar wind speed at 1AU. A good agreement between numerical prediction and solar wind speed observations has been found.

Telluric currents due to geomagnetic field variations have long been known to cause variations in pipe-to-soil potentials (PSP) on pipelines. These are increasingly being taken into account in the design of cathodic protection systems for new pipelines. Online services are available for modelling telluric currents but cannot handle all pipeline configurations. This paper describes the development of a new telluric simulator, based on a more versatile modeling technique that can include more details of a pipeline such as branches and other features. This can show the pipe-to-soil potentials produced by specified telluric electric fields. Descriptions are also provided for features of the telluric simulator that allow modeling of the pipeline response using electric fields calculated for past geomagnetic disturbances. These features allow pipeline designs to be checked under realistic conditions and modifications to the design to be tested.

AbstractCoronal mass ejections (CME) and associated interplanetary-propagated solar wind disturbances are the established causes of the geomagnetic storms which, in turn, create the most hazardous impacts on power grids. These impacts are due to the large geomagnetically induced currents (GIC) associated with variations of geomagnetic field during storms, which, flowing through the transformer windings, cause extra magnetisation. That can lead to transformer saturation and, in extreme cases, can result in power blackouts. Thus, it is of practical importance to study the solar causes of the large space weather events. This paper presents the example of the space weather chain for the event of 5-6 November 2001 and a table providing complete overview of the largest solar events during solar cycle 23 with their subsequent effects on interplanetary medium and on the ground. This compact overview can be used as guidance for investigations of the solar causes and their predictions, which has a practical importance in everyday life.

Geomagnetically induced currents (GICs) are identified as a potential hazard to power grids. Significant progress in understanding the physical processes leading to GIC production and its effects on power grid components have been made in recent years. With the development of a GIC benchmark network, researchers are now equipped with a test model that can be used to separate the effects of different environmental conditions from effects of network configuration on the distribution of GIC in a system. This paper describes the effects of the environmental conditions (i.e., geomagnetic variations and earth conductivity structures) on GIC in the benchmark network. Geomagnetic variations during the October 29-31, 2003, space weather events are used, together with two realistic models of the earth conductivity (i.e., more resistive and more conductive). The results of the modeling of different geophysical scenarios expressed in terms of GIC distributions through the system and as two GIC-related indices show the crucial importance of the geophysical conditions in assessing the GIC risk to power systems.

The connection between solar activity and adverse phenomena in the Earth’s environment that can affect space and ground based technologies has spurred interest in Space Weather (SW) research. A great effort has been put on the development of suitable models that can provide advanced forecast of SW events. With the progress in computational technology, it is becoming possible to develop operational large scale physics based models which can incorporate the most important physical processes and domains of the Sun-Earth system. In order to enhance our SW prediction capabilities we are developing advanced numerical tools. With operational requirements in mind, our goal is to develop a modular simulation framework of propagation of the disturbances from the Sun through interplanetary space to the Earth. Here, we report and discuss on the development of coronal field and solar wind components for a large scale MHD code. The model for these components is based on a potential field source surface model and an empirical Wang-Sheeley-Arge solar wind relation. Keywords—Space weather, numerical modeling, coronal field, solar wind.

A highly elliptical orbit (HEO) with a 16-h period is proposed for continuous meteorological imaging of polar regions from a two-satellite constellation. This orbit is characterized by three apogees (TAP) separated by 120. The two satellites are 8 h apart, with repeatable ground track in the course of 2 days. Advantages are highlighted in comparison to the Molniya 12-h orbit described in detail in a previous study (Trishchenko and Garand). Orbital parameters (period, eccentricity, and inclination) are obtained as a result of an optimization process. The principles of orbit optimization are based on the following four key requirements: spatial resolution (apogee height), the altitude of crossing the trapped proton region at the equator (minimization of radiation doze caused by trapped protons), imaging time over the polar regions, and the stability of the orbit, which is mostly defined by the rotation of perigee. The interplay between these requirements points to a 16-h period with an eccentricity of 0.55 as the optimum solution. The practical range of orbit inclinations that could be maintained during the spacecraft lifetime can vary from a critical value of 63.435 degrees to 70 degrees (subject to the amount of propellant available for orbital maneuvers). In comparison to Molniya, this type of orbit reduces the radiation exposure to high-energy protons by factor of 10(3)-10(4). On the other hand, the main advantage of 16 h versus longer orbital periods up to 24 h is better spatial resolution as a result of a lower apogee height. A two-satellite TAP constellation with an orbital inclination of 66 provides 100% temporal coverage above 60 degrees N, >95% above 55 degrees N, >85% above 50 degrees N, and >75% above 45 degrees N.