Perturbation Events Research Articles

Magnetosphere–Ionosphere Drivers of Transient‐Large‐Amplitude Geomagnetic Disturbances: Statistical Analysis and Event Study

AbstractWe present a comprehensive statistical analysis of high‐frequency transient‐large‐amplitude (TLA) magnetic perturbation events that occurred at 12 high‐latitude ground magnetometer stations throughout Solar Cycle 24 from 2009 to 2019. TLA signatures are defined as one or more second‐timescale dB/dt interval with magnitude ≥6 nT/s within an hour event window. This study characterizes high‐frequency TLA events based on their spatial and temporal behavior, relation to ring current activity, auroral substorms, and nighttime geomagnetic disturbance (GMD) events. We show that TLA events occur primarily at night, solely in the high‐latitude region above 60° geomagnetic latitude, and commonly within 30 min of substorm onsets. The largest TLA events occurred more often in the declining phase of the solar cycle when ring current activity was lower and solar wind velocity was higher, suggesting association to high‐speed streams caused by coronal holes and subsequent corotating interaction regions reaching Earth. TLA perturbations often occurred preceding or within the most extreme nighttime GMD events that have 5–10 min timescales, but the TLA intervals were often even more localized than the ∼300 km effective scale size of GMDs. We provide evidence that shows TLA‐related GMD events are associated with dipolarization fronts in the magnetotail and fast flows toward Earth and are closely temporally associated with poleward boundary intensifications (PBIs) and auroral streamers. The highly localized behavior and connection to the most extreme GMD events suggests that TLA intervals are a ground manifestation of features within rapid and complex ionospheric structures that can drive geomagnetically induced currents.

Nearshore subtidal community response during and after sediment disturbance associated with dam removal

Dam removal is used increasingly to restore aquatic ecosystems and remove unnecessary or high-risk infrastructure. As the number of removals increases, there is a growing understanding about the hydrologic, geomorphic, and ecological responses to these removals. Most dam removal studies, however, focus on river and watershed responses to dam removal. The removal of two dams on the Elwha River provided a unique opportunity to characterize the response of nearshore (coastal) ecosystems. We conducted SCUBA surveys between 2011 and 2022 to quantify trajectories of change in a nearshore ecosystem during and after dam removal. We focused on the degree to which the abundances of kelp, benthic invertebrates, and fish changed in response to patterns of sediment fluxes during and after dam removal. Our findings point to two pathways of response depending on the disturbance mechanism and species type. Sites with persistent sediment deposition were characterized by wholesale community changes that did not recover to a before dam removal condition. Instead, the sites were colonized by new species that were largely absent prior to dam removal. Sites that experienced high turbidity but lacked persistent seafloor deposition were primarily characterized by a reduction in the abundance of kelp and other algae during dam removal and a rapid recovery after sediment flux to the nearshore declined. Dam removal influences on invertebrates and fish at these sites were more variable, benefiting some species and disadvantaging others. In addition to dam removal, sea star wasting syndrome and a marine heatwave exerted distinct controls on subtidal communities during the same period. The loss of the predatory sea star Pycnopodia helianthoides was associated with gains in some of its prey species, and kelp community changes reflected regional trends in ocean temperature and kelp abundance. The results presented here have important implications for understanding the response of marine ecosystems to future dam removals and similar sediment perturbation events.

A method for searching the best static program for nuclear power unit control in the event of perturbations of different nature

Considering the current state of Ukraine's energy sector in a dangerous and unstable environment, the operation of nuclear power plants is one of the most important sources of electricity supply for the state. The development of the theory of optimal control and the technical level of automated process control systems in the current state of affairs make it possible not to reduce the efficiency of controlling a nuclear power unit, not only by changing the parameters at any load, but also by changing the structure of automation equipment capable of implementing a certain static control program of power, which currently eliminates the influence of internal and external disturbances, without reducing safety indicators. The article considers the situation when the linear programming method is not applicable for solving the control problem. In this case, the decision at each stage does not depend on the decision at the previous one. This is where target programming comes in handy –this is one of the methods of multi-criteria optimization, in the theory of which decision-making problems are solved simultaneously according to several criteria. The purpose of the work is to ensure the safe and efficient operation of a nuclear power unit in an energy system that is not constant in operational states. Using a mathematical model of a nuclear power unit, experiments were carried out to simulate the switching of controlprograms. The simulation model of the automated power control system, based on the bumpless switching of static programs according to the technological methods of operating power equipment, made it possible to form a change in the current model of the control program, as well as eliminate the static control error and get the response of process dependent parameters to program switching. Also, based on the results of the research, an objective function was proposed, which includes three normalized criteria with different objectives. In particular, the problem of optimizing the switching of static power control programs was solved by minimizing the objective function, which combines such characteristics as the efficiency and safety of the operation of a nuclear power unit.

Resilience and Systems—A Building Structure Case Example

The resilience of building structures—as plain technical/physical/engineering systems or complex sociotechnical systems exposed to perturbations and change—has become increasingly important as natural disasters are on the rise and the world is changing rapidly. Existing resilience frameworks are focused mainly on the responses of building systems to perturbation events and their functional recovery, while change appears to be left out. This study applies the resilience system interpretation framework, which defines resilience in a cross-disciplinary environment as adaptation and adaptive systems, to analyze actual and conceptual building structure systems. The system framework, using modern control systems theory, defines resilience as the ability of the system state and form to return to their initial or other suitable states or forms through passive and active feedback mechanisms. A sample SMRF office building structure system is utilized to simulate the system state and form return abilities that are demonstrated by the system functional recovery time and functional recovery curve shape, respectively. This novel understanding of resilience accommodates a holistic and systematic integration of both perturbation and change in the portfolios of various building structures. The framework also provides a practical roadmap for resilience design and building of structures that effectively respond to perturbation while dynamically adapting to change in order to avoid obsolescence, as well as to increase the building’s useful life.

Algal blooms as a reactive dynamic response to seasonal perturbation in an experimental system

Algal blooms are typical of many aquatic freshwater ecosystems in seasonal environments. Such blooms could derive from transient reactive dynamics of algae and limiting nutrients following seasonal perturbation events. Linking parameter estimates derived from previously published lab experiments with empirical estimates of algal density dependence, we modeled dynamic interactions between nutrients and the green algal species Chlorella vulgaris and tested model predictions in a dozen 140 L mesocosms supplied with bi-weekly inputs of liquid fertilizer. Consistent with the reactive nutrient-driven model, Chlorella populations exhibited an initial surge in abundance over the first month followed by collapse as they rapidly converged on stable equilibria. The reactive model suggests that the magnitude of transient blooms is positively related to the augmentation of nutrients and depression of algae over the winter period. The magnitude of both algal peaks and equilibrium abundance was positively related to fertilizer loading, as predicted by the reactive model. Our results suggest that transient reactive responses to climate-driven perturbation events can be an important contributor to seasonal algal blooms observed in many temperate freshwater ecosystems. Controlled experimental studies such as ours may be helpful in understanding and potentially mediating the impact of fertilizer run-off on freshwater systems in temperate agricultural landscapes.

Automatic Recognition of Constant-Frequency Electromagnetic Disturbances Observed by the Electric Field Detector on Board the CSES

Since the CSES (China Seismo-Electromagnetic Satellite) has been in orbit, it has detected a large number of constant-frequency electromagnetic disturbances (CFEDs), which are horizontal lines on the spectrum. In this paper, we present an algorithm for automatic recognition of CFEDs based on computer vision technology. The relevant results are of great significance for analysis of perturbation events and mining of the transformation laws of global space events. First, a grayscale spectrogram is obtained; then, a horizontal convolution kernel is used to enhance the horizontal edge features of the grayscale graph, and finally, black-and-white binarization is performed to complete data preprocessing. The preprocessed data are then fed into an unsupervised cluster model for training and recognition to realize automatic recognition of CFEDs. Experimental results show that the CFED recognition algorithm proposed in this paper is effective, with a recognition accuracy of more than 98%.

Quantifying the effects of extreme events and oceanographic variability on the spatiotemporal biomass and distribution of two key euphausiid prey species

Euphausiids form a critical component of oceanic food chains and individual species vary in their responses to perturbation events. We aimed to establish if patterns of fine scale oceanographic variability and larger-scale climate events such as marine heatwaves (MHWs) could be linked with spring variability in the biomass of two key forage species in the northeast Pacific Ocean, Euphausia pacifica and Thysanoessa spinifera. To achieve this, we used long-term datasets from the west coast of Vancouver Island Canada, an important commercial fishing area, to first quantify interannual signals of variability in fine-scale oceanographic conditions using multivariate analysis. We then used geostatistical spatiotemporal modelling to quantify the effects on species-specific euphausiid biomass. Oceanographic data showed that the effects of warm events are not always observable, and effects vary across small spatial scales. Warming due to the 2014-2016 MHW was relatively mild on the continental shelf during spring (<1°C above climatology). Spring biomass of euphausiids, particularly E. pacifica, peaked in 2015, and all euphausiid groups analysed (E. pacifica, T. spinifera and total euphausiids) exhibited significant correlations with positive phases of the Pacific Decadal Oscillation. These results have implications for marine predators as euphausiids may act as system stabilisers in the northeast Pacific, thereby potentially increasing ecosystem resilience during extreme events.

Enabling Variable High Spatial Resolution Retrieval From a Long Pulse BOTDA Sensor

Spatial resolution (SR) is one of the most important parameters of Brillouin optical time-domain analysis (BOTDA) sensors, which determines the minimum length that a perturbation event can be distinguished. In the field of Internet of Things (IoT), there is an urgent need for sensors with large-scale high-precision sensing capability for scenarios, such as intelligent monitoring of production lines and urban infrastructure. Conventionally, the SR is normally restricted to be longer than 1 m due to the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 10$ </tex-math></inline-formula> -ns acoustic lifetime limitation in silica optical fibers. For long-distance smart monitoring systems, the SR is generally on the order of several meters or even worse. However, it does not meet the needs of many applications. Therefore, there is an urgent need to achieve SR in the submeter magnitude. In this work, for the first time to the best of our knowledge, we propose a convolutional neural network (CNN) to process the data of conventional BOTDA sensors, which achieves unprecedented performance improvement that allows to directly retrieve submeter SR from the sensing system that use long pump pulses. By using the simulated Brillouin gain spectrums (BGSs) as the CNN input and the corresponding high SR Brillouin frequency shift (BFS) as the output target, the trained CNN is able to obtain an SR higher than the theoretical value determined by the pump pulse width. In the experiment, the CNN accurately retrieves 0.5-m hotspots from the measured BGS with pump pulses from 20 to 50 ns, and the acquired BFS is in great agreement with 45/40 ns differential pulse-width pair (DPP) measurement results. Compared with the DPP technique, the proposed CNN demonstrates a twofold improvement in BFS uncertainty with only half the measurement time. In addition, by changing the training data sets, the proposed CNN can obtain tunable high SR retrieval based on conventional BOTDA sensors that use long pulses without any requirement of hardware modifications. It is worth mentioning that the proposed method is also applicable to larger pulse widths to retrieve a submeter SR. The proposed data post-processing approach paves the way to enable novel high SR BOTDA sensors, which brings substantial improvement over the state-of-the-art techniques in terms of system complexity, measurement time, reliability, etc.

DOES PERTURBATION-BASED BALANCE TRAINING ON COMMERCIAL TREADMILLS IMPROVE BALANCE RECOVERY IN OLDER ADULTS?

Abstract Background Perturbation-based training (PBT) is a balance training method that causes a trip like event requiring a rapid step response to regain balance. There are numerous examples in the literature demonstrating the effectiveness of PBT but the need to use an expensive treadmill in a scientific laboratory limits the general applicability of PBT as a community-based intervention. A possible solution is to rapidly stop the treadmill belt during walking using the e-brake as the perturbation event. Importantly this could be performed on a commercially available, lower cost treadmill. Therefore, the purpose of this study was to evaluate the effectiveness of a commercial treadmill during PBT. Methods Seventeen participants completed either 9 weeks of PBT or conventional balance training based on ACSM guidelines. During an initial and final testing session participants balance recovery performance was evaluated. Participants were released from a forward static lean angle and asked to recover with a single step, during this test their movement was recorded and subsequently used to determine the Margin or Stability pre- and post-training. Participants were tracked for 6 months following the intervention and falls were recorded on a weekly basis. Results and Summary: There was no difference in balance recovery performance between groups following the training intervention and there was no difference in fall rate between groups in the 6-month follow-up period. We conclude that overall using the e-brake of a commercial treadmill is ineffective as a PBT strategy as it elicits no greater benefit than conventional exercise training.

Geomagnetic Disturbances That Cause GICs: Investigating Their Interhemispheric Conjugacy and Control by IMF Orientation

AbstractNearly all studies of impulsive geomagnetic disturbances (GMDs, also known as magnetic perturbation events MPEs) that can produce dangerous geomagnetically induced currents (GICs) have used data from the northern hemisphere. In this study, we investigated GMD occurrences during the first 6 months of 2016 at four magnetically conjugate high latitude station pairs using data from the Greenland West Coast magnetometer chain and from Antarctic stations in the conjugate AAL‐PIP magnetometer chain. Events for statistical analysis and four case studies were selected from Greenland/AAL‐PIP data by detecting the presence of &gt;6 nT/s derivatives of any component of the magnetic field at any of the station pairs. For case studies, these chains were supplemented by data from the BAS‐LPM chain in Antarctica as well as Pangnirtung and South Pole in order to extend longitudinal coverage to the west. Amplitude comparisons between hemispheres showed (a) a seasonal dependence (larger in the winter hemisphere), and (b) a dependence on the sign of the By component of the interplanetary magnetic field (IMF): GMDs were larger in the north (south) when IMF By was &gt;0 (&lt;0). A majority of events occurred nearly simultaneously (to within ±3 min) independent of the sign of By as long as |By| ≤ 2 |Bz|. As has been found in earlier studies, IMF Bz was &lt;0 prior to most events. When IMF data from Geotail, Themis B, and/or Themis C in the near‐Earth solar wind were used to supplement the time‐shifted OMNI IMF data, the consistency of these IMF orientations was improved.

Lacustrine redox variations in the Toarcian Sichuan Basin across the Jenkyns Event

The Early Jurassic Jenkyns Event (~183 Ma) represents a major environment perturbation event, characterized by the negative carbon isotope excursion during the early Toarcian. Reconstruction of redox conditions, especially in the mega-lakes, across the Jenkyns Event is of significance to understand the biogeochemical dynamics on land at the time. Here, we report iron speciation and trace metal data from the two drill cores (LQ104X and X3 wells) with different depositional environments in the lacustrine Sichuan Basin of SW China. Results show that the water column in the Sichuan Basin experienced a significant shift of redox conditions in the Toarcian. Frequent development of anoxic-ferruginous conditions interspersed with significant euxinic episodes across the Jenkyns Event. Conversely, during the pre/post-Jenkyns Event interval, dominantly oxic conditions, with short-lived anoxic-ferruginous or euxinic conditions, developed in the water column of the Sichuan Basin. We then proposed three possible mechanisms interdependent in nature that could have induced the water-column redox variability in Toarcian lakes: (1) lake stratifications, (2) enhanced methane release from the lake floor under low sulfate conditions that exhausted bottom water oxygen, and (3) lake eutrophication. We further anticipated that a close link between redox shift and ecological stress in the Sichuan Basin across the Jenkyns Event.

'Only One Earth' – Celebrating soil science on World Environment Day 2022

'Only One Earth' – Celebrating soil science on World Environment Day 2022

Fish-parasite interaction networks reveal latitudinal and taxonomic trends in the structure of host-parasite associations.

In recent years, treating host–parasite associations as bipartite interaction networks has proven a powerful tool to identify structural patterns and their likely causes in communities of fish and their parasites. Network analysis allows for both community-level properties to be computed and investigated, and species-level roles to be determined. Here, using data from 31 host–parasite interaction networks from local fish communities around the world, we test for latitudinal trends at whole-network level, and taxonomic patterns at individual parasite species level. We found that while controlling for network size (number of species per network), network modularity, or the tendency for the network to be subdivided into groups of species that interact mostly with each other, decreased with increasing latitude. This suggests that tropical fish–parasite networks may be more stable than those from temperate regions in the event of community perturbations, such as species extinction. At the species level, after accounting for the effect of host specificity, we observed no difference in the centrality of parasite species within networks between parasites with different transmission modes. However, species in some taxa, namely branchiurans, acanthocephalans and larval trematodes, generally had higher centrality values than other parasite taxa. Because species with a central position often serve as module connectors, these 3 taxa may play a key role in whole-network cohesion. Our results highlight the usefulness of network analysis to reveal the aspects of fish–parasite community interactions that would otherwise remain hidden and advance our understanding of their evolution.

Marine anoxia linked to abrupt global warming during Earth’s penultimate icehouse

Piecing together the history of carbon (C) perturbation events throughout Earth’s history has provided key insights into how the Earth system responds to abrupt warming. Previous studies, however, focused on short-term warming events that were superimposed on longer-term greenhouse climate states. Here, we present an integrated proxy (C and uranium [U] isotopes and paleo CO2) and multicomponent modeling approach to investigate an abrupt C perturbation and global warming event (∼304 Ma) that occurred during a paleo-glacial state. We report pronounced negative C and U isotopic excursions coincident with a doubling of atmospheric CO2 partial pressure and a biodiversity nadir. The isotopic excursions can be linked to an injection of ∼9,000 Gt of organic matter–derived C over ∼300 kyr and to near 20% of areal extent of seafloor anoxia. Earth system modeling indicates that widespread anoxic conditions can be linked to enhanced thermocline stratification and increased nutrient fluxes during this global warming within an icehouse.

Monitoring of Geomagnetic and Telluric Field Disturbances in the Russian Arctic

The influence of space factors on technological systems in the Arctic (power transmission lines, oil/gas pipelines) has become critically important. To examine in depth these effects, an archive of digital 1 min data from Soviet/Russian magnetic stations deployed along the Arctic coast was created, starting from 1983 to the present. All data from various sources were converted to daily files in standard IAGA-2002 format and supplemented with quick-look magnetograms. Some of these data are included already in the existing world magnetic field databases, but not all. Examples of disturbances known to excite intense geomagnetically induced currents in power transmission lines were presented: irregular Pi3 pulsations and magnetic perturbation events. The database was augmented with the global 3D model of the Earth’s conductivity structure. The given example showed how the combined usage of the geomagnetic field database and the conductivity model enables one to synthesize the geoelectric field response to geomagnetic variations, and to assess the distortions of the pipeline-soil potential. To determine regions most susceptible to geomagnetic hazard, a map with normalized telluric fields was created for a uniform sinusoidally varying magnetic disturbance. This map showed that the largest electrotelluric potentials and field are induced in regions with a high resistivity (e.g., Kola Peninsula and Ural Mountains). This database can be also a useful support for space missions in the magnetosphere. The database is publicly available on the anonymous FTP site.

Intravital Imaging of the Murine Subventricular Zone with Three Photon Microscopy.

The mouse subventricular zone (SVZ) produces neurons throughout life. It is useful for mechanism discovery and is relevant for regeneration. However, the SVZ is deep, significantly restricting live imaging since current methods do not extend beyond a few hundred microns. We developed and adapted three-photon microscopy (3PM) for non-invasive deep brain imaging in live mice, but its utility in imaging the SVZ niche was unknown. Here, with fluorescent dyes and genetic labeling, we show successful 3PM imaging in the whole SVZ, extending to a maximum depth of 1.5 mm ventral to the dura mater. 3PM imaging distinguished multiple SVZ cell types in postnatal and juvenile mice. We also detected fine processes on neural stem cells interacting with the vasculature. Previous live imaging removed overlying cortical tissue or lowered lenses into the brain, which could cause inflammation and alter neurogenesis. We found that neither astrocytes nor microglia become activated in the SVZ, suggesting 3PM does not induce major damage in the niche. Thus, we show for the first time 3PM imaging of the SVZ in live mice. This strategy could be useful for intravital visualization of cell dynamics, molecular, and pathological perturbation and regenerative events.

Вплив конструктивних і експлуатаційних факторів на стійкість руху автопоїзда з причепом категорії О1

The issues of stability and controllability of cars and road trains (ATZ) in connection with their practical importance have been studied by many researchers. If the issues of transportation of bulky goods are studied well enough, then for the transportation of light cargo, which uses low-capacity road trains with simple single- or two-axle trailers, the issues of stability are not fully studied. Recommendations for changing the design parameters to improve a particular type of stability are different and sometimes contradict the requirements for other performance of the car, in particular, its smoothness and passability. Qualitative assessment of stability is performed on the basis of the general theory of stability of motion AM Lyapunov. Steady motion according to Lyapunov is realized in a previously unknown region of initial perturbations, which are called the region of attraction of undisturbed motion. There is a problem of defining the boundaries of this area. To solve it, the system of equations of plane-parallel motion of a road train with a trailer of category O1 was improved, from which the critical speed of rectilinear motion and the rate of oscillation instability were determined, and the factors influencing its numerical value were analyzed. The analysis of calculations showed that in the event of perturbation at speeds up to 31 m / s (30.8 m / s) the nature of changes in the lateral and angular velocities of the traction vehicle during the transient process is extinguished. Under the same conditions, when the velocity increases above 31 m / s (31.5 m / s), the nature of the change in lateral and angular velocities also fades, but there are fluctuations. At increase in speed to 32 m / s fluctuations of parameters of movement will be divergent that will lead to loss of stability and impossibility of the further movement. This movement should be considered unstable, which should be avoided. The stability of motion can be judged to a greater extent by the magnitude of the lateral accelerations acting in the center of mass of the individual links. The stability of the road train under consideration at nominal parameters of loading, air pressure in tires of all wheels, symmetrical loading of the trailer, loading on the traction coupling device within 500 N is provided, in particular critical speed of rectilinear movement made 33,97 m / s. oscillating instability 31.5 m / s), which is much higher than the normalized value of the maximum speed for road trains with trailers of category O1 (25 m / s), the maximum lateral acceleration when performing maneuvers such as circular motion, steering wheel jerk and "shift" is not exceeded the maximum allowable 0.45g.

SECS Analysis of Nighttime Magnetic Perturbation Events Observed in Arctic Canada

AbstractLarge changes of the magnetic field associated with magnetic perturbation events (MPEs) with amplitudes |ΔB| of hundreds of nT and 5–10 min duration have been frequently observed within a few hours of midnight. This study compares the statistical location of nighttime MPEs with |dB/dt| ≥ 6 nT/s within the auroral current system observed during 2015 and 2017 at two stations, Cape Dorset and Kuujjuarapik, in Eastern Canada. Maps of the two dimensional nightside auroral current system were derived using the Spherical Elementary Current Systems (SECS) technique. Analyses were produced at each station for all events, and for premidnight and postmidnight subsets. We examine four MPE intervals in detail, two accompanied by auroral images, and show the varying associations between MPEs and overhead ionospheric current systems including electrojets and the field‐aligned like currents. We find 225 of 279 MPEs occurred within the westward electrojet and only 3 within the eastward electrojet. For the premidnight MPEs 100 of 230 events occurred within the Harang current system while many of the remainder occurred within either the downward region 1 current system or the upward region 2 current system. Many of the 49 postmidnight MPEs occurred in either the downward region 1 (11 events) or upward region 2 current system (27 events). These result suggest that the source of MPEs in the premidnight sector is somewhere between the inner to mid plasma sheet and the source for the MPEs in the postmidnight sector is somewhere between the inner magnetosphere and the inner plasma sheet.

Envisioning a resilient future for biodiversity conservation in the wake of the COVID-19 pandemic.

As the COVID‐19 pandemic continues to affect societies across the world, the ongoing economic and social disruptions are likely to present fundamental challenges for current and future biodiversity conservation.We review the literature for outcomes of past major societal, political, economic and zoonotic perturbations on biodiversity conservation, and demonstrate the complex implications of perturbation events upon conservation efforts. Building on the review findings, we use six in‐depth case studies and the emerging literature to identify positive and negative outcomes of the COVID‐19 pandemic, known and anticipated, for biodiversity conservation efforts around the world.A number of similarities exist between the current pandemic and past perturbations, with experiences highlighting that the pandemic‐induced declines in conservation revenue and capacity, livelihood and trade disruptions are likely to have long‐lasting and negative implications for biodiversity and conservation efforts.Yet, the COVID‐19 pandemic also brought about a global pause in human movement that is unique in recent history, and may yet foster long‐lasting behavioural and societal changes, presenting opportunities to strengthen and advance conservation efforts in the wake of the pandemic. Enhanced collaborations and partnerships at the local level, cross‐sectoral engagement, local investment and leadership will all enhance the resilience of conservation efforts in the face of future perturbations. Other actions aimed at enhancing resilience will require fundamental institutional change and extensive government and public engagement and support if they are to be realised.The pandemic has highlighted the inherent vulnerabilities in the social and economic models upon which many conservation efforts are based. In so doing, it presents an opportunity to reconsider the status quo for conservation, and promotes behaviours and actions that are resilient to future perturbation. A free Plain Language Summary can be found within the Supporting Information of this article.

Superposed Epoch Analysis of Nighttime Magnetic Perturbation Events Observed in Arctic Canada

AbstractRapid changes of magnetic fields associated with nighttime magnetic perturbation events (MPEs) with amplitudes |ΔB| of hundreds of nT and 5–10 min duration can induce geomagnetically induced currents (GICs) that can harm technological systems. Here we present superposed epoch analyses of large nighttime MPEs (|dB/dt| ≥ 6 nT/s) observed during 2015 and 2017 at five stations in Arctic Canada ranging from 64.7° to 75.2° in corrected geomagnetic latitude (MLAT) as functions of the interplanetary magnetic field (IMF), solar wind dynamic pressure, density, and velocity, and the SML, SMU, and SYM/H geomagnetic activity indices. Analyses were produced for premidnight and postmidnight events and for three ranges of time after the most recent substorm onset: (a) 0–30 min, (b) 30–60 min, and (c) &gt;60 min. Of the solar wind and IMF parameters studied, only the IMF Bz component showed any consistent temporal variations prior to MPEs: a 1–2 h wide 1–3 nT negative minimum at all stations beginning ∼30–80 min before premidnight MPEs, and minima that were less consistent but often deeper before postmidnight MPEs. Median, 25th, and 75th percentile SuperMAG auroral indices SML (SMU) showed drops (rises) before pre‐ and post‐midnight type A MPEs, but most of the MPEs in categories B and C did not coincide with large‐scale peaks in ionospheric electrojets. Median SYM/H indices were flat near −30 nT for premidnight events and showed no consistent temporal association with any MPE events. More disturbed values of IMF Bz, Psw, Nsw, SML, SMU, and SYM/H appeared postmidnight than premidnight.