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We analyzed the contribution of electromagnetic ion cyclotron (EMIC) wave driven electron loss to a flux dropout event in September 2017. The evolution of electron phase space density (PSD) through the dropout showed the formation of a radially peaked PSD profile as electrons were lost at high L*, resembling distributions created by magnetopause shadowing. By comparing 2D Fokker Planck simulations of pitch angle diffusion to the observed change in PSD, we found that the μ and K of electron loss aligned with maximum scattering rates at dropout onset. We conclude that, during this dropout event, EMIC waves produced substantial electron loss. Because pitch angle diffusion occurred on closed drift paths near the last closed drift shell, no radial PSD minimum was observed. Therefore, the radial PSD gradients resembled solely magnetopause shadowing loss, even though the local pitch angle scattering produced electron losses of several orders of magnitude of the PSD. Plain Language Summary: Extremely energetic charged particles become trapped by Earth's geomagnetic field, forming the Van Allen radiation belts. The total amount of radiation trapped within these belts varies depending on the solar wind conditions, which can disturb the geomagnetic field to produce geomagnetic storms. At the beginning of a geomagnetic storm, there is a relative calm in the radiation belt, produced by the rapid drainage of electrons from the geomagnetic field. It is not fully understood if these electrons are primarily lost into the solar wind, or if they are lost into Earth's atmosphere. In this study, we analyze the remaining trapped electrons to reconstruct the mechanisms of electron escape at the beginning of a geomagnetic storm in September 2017. While previous work found that electrons were primarily lost into the solar wind, we found that loss into the atmosphere also played an important role. Furthermore, we showed that drainage of electrons into the atmosphere can be mistaken for loss into the solar wind if the energy and trajectory of lost electrons are not carefully considered. Key Points: Characterizing electron loss through peaks and minima in radial phase space density can misrepresent simultaneous loss mechanismsAnalysis of electron loss across all adiabatic invariants μ, K, and L*, is necessary to correctly identify loss mechanismsObservational analysis of phase space density data alone cannot be used to quantify individual contributions of simultaneous loss processes [ABSTRACT FROM AUTHOR]

The Super Dual Auroral Radar Network (SuperDARN) is a collection of radars built to study ionospheric convection. We use a 7‐year archive of SuperDARN convection maps, processed in 3 different ways, to build a statistical understanding of dusk‐dawn asymmetries in the convection patterns. We find that the data set processing alone can introduce a bias which manifests itself in dusk‐dawn asymmetries. We find that the solar wind clock angle affects the balance in the strength of the convection cells. We further find that the location of the positive potential foci is most likely observed at latitudes of 78° for long periods (>300 min) of southward interplanetary magnetic field (IMF), as opposed to 74° for short periods (<20 min) of steady IMF. For long steady dawnward IMF the median is also at 78°. For long steady periods of duskward IMF, the positive potential foci tends to be at lower latitudes than the negative potential and vice versa during dawnward IMF. For long periods of steady Northward IMF, the positive and negative cells can swap sides in the convection pattern. We find that they move from ∼0–9 MLT to 15 MLT or ∼15–23 MLT to 10 MLT, which reduces asymmetry in the average convection cell locations for Northward IMF. We also investigate the width of the region in which the convection returns to the dayside, the return flow width. Asymmetries in this are not obvious, until we select by solar wind conditions, when the return flow region is widest for the negative convection cell during Southward IMF. Plain Language Summary: At high latitudes, near the Earth's magnetic pole, the ionosphere moves around in a dual‐cell pattern: The convection moves from the dayside, over the magnetic pole toward the nightside and then flows return back to the dayside at lower latitudes. Both cells tend to be centered away from the pole, one toward the dusk side and one toward the dawn side. The two cells have a tendency to be asymmetric with the dusk cell typically larger and stronger. Asymmetries in the two convection cells are often attributed to changes in the solar wind as there is a physical connection between the ionosphere and the solar wind. The mechanisms which describe this interaction are well known but some of the data sets with which we measure ionospheric convection have unquantified uncertainties associated with them. One of the longest running measurement systems of the ionospheric convection is the Super Dual Auroral Radar Network (SuperDARN). This ground‐based system was built specifically to measure ionospheric convection and it is often used to make convection maps of the ionosphere. Over the years, more radars have been added to the network and the software used to process the data has been updated. In this study we use different versions of the convection maps to statistically investigate 7 years of ionospheric convection asymmetries and understand which of the asymmetries were introduced by a change in the data set and which by the solar wind. We look at the location and strength of the cells and the width of the return flow region, which constrains the size of the cells. Key Points: We study dusk‐dawn asymmetries in 7 years of Super Dual Auroral Radar Network convection maps which are introduced by solar wind orientations, or data processingAsymmetries due to interplanetary magnetic field By can occur in the strength and location of the convection cells, and the return flow widthAsymmetries due to the background model are likely to occur in the locations of the convection cells [ABSTRACT FROM AUTHOR]

The Super Dual Auroral Radar Network (SuperDARN) was built to study ionospheric convection and has in recent years been expanded geographically. Alongside software developments, this has resulted in many different versions of the convection maps data set being available. Using data from 2012 to 2018, we produce five different versions of the widely used convection maps, using limited backscatter ranges, background models and the exclusion/inclusion of data from specific radar groups such as the StormDARN radars. This enables us to simulate how much information was missing from older SuperDARN research. We study changes in the Heppner‐Maynard boundary (HMB), the cross polar cap potential (CPCP), the number of backscatter echoes (n) and the χ2/n statistic which is a measure of the global agreement between the measured and fitted velocities. We find that the CPCP is reduced when the PolarDARN radars are introduced, but then increases again when the StormDARN radars are added. When the background model is changed from the RG96 model, to the most recent TS18 model, the CPCP tends to decrease for lower values, but tends to increase for higher values. When comparing to geomagnetic indices, we find that there is on average a linear relationship between the HMB and the geomagnetic indices, as well as n, which breaks when the HMB is located at latitudes below ∼50° due to the low observational density. Whilst n is important in constraining the maps (maps with n > 400 data points are unlikely to differ), it is insufficient as the sole measure of quality. Plain Language Summary: The ionosphere, where space begins and the atmosphere ends, moves as a result of the Earth's magnetic field coupling with the Sun. The Super Dual Auroral Radar Network (SuperDARN) was built around the Earth's magnetic poles to study this phenomenon, known as ionospheric convection. Combining many line‐of‐sight convection measurements, we are able to build global maps of ionospheric convection from SuperDARN data. This encapsulates dynamics which are central to space weather phenomena. SuperDARN, which has been gathering data for decades, has over time undergone numerous transformations, including the development of new processing software and more radars being added to the network. Using data from the years 2012–2018, we perform a statistical analysis on processed SuperDARN convection maps for the entire data set and assess systematically how the data set has changed over the years. We consider how the addition of more data and differences to the convection mapping procedures can affect scientific studies in the context of this large database. Key Points: We identify changes in derived convection maps when PolarDARN and StormDARN are added, and show the impact of different processingDerived convection parameters are highly susceptible to processing variables and which radars are includedWe show how the number of backscatter echoes per map is critical to the integrity of the maps, and discuss how this impacts map quality [ABSTRACT FROM AUTHOR]

Loss mechanisms act independently or in unison to drive rapid loss of electrons in the radiation belts. Electrons may be lost by precipitation into the Earth's atmosphere, or through the magnetopause into interplanetary space—a process known as magnetopause shadowing. While magnetopause shadowing is known to produce dropouts in electron flux, it is unclear if shadowing continues to remove particles in tandem with electron acceleration processes, limiting the overall flux increase. We investigated the contribution of shadowing to overall radiation belt fluxes throughout a geomagnetic storm starting on the 7 September 2017. We use new, multimission phase space density calculations to decipher electron dynamics during each storm phase and identify features of magnetopause shadowing during both the net‐loss and the net‐acceleration storm phases on sub‐hour time scales. We also highlight two distinct types of shadowing; "direct," where electrons are lost as their orbit intersects the magnetopause, and "indirect," where electrons are lost through ULF wave driven radial transport toward the magnetopause boundary. Plain Language Summary: Charged particles with extremely high energies are trapped by Earth's geomagnetic field. These particles form rings around Earth called the Van Allen radiation belts, which vary in intensity. This radiation poses a risk to satellites orbiting Earth, so it is important to understand how changes in geomagnetic conditions produce variations in the radiation belt intensity. In this work, we take measurements of electron radiation from many satellites to observe electron "dropouts," where nearly the entire radiation belt is lost in a matter of hours. We found that it is necessary to use multimission measurements to make observations of dropouts because a dropout may occur quicker than a single satellite can traverse the radiation belt. In early September 2017, we observed that movements of the geomagnetic outer boundary, the magnetopause, were responsible for removing electrons, combined with diffusive processes. This agreed with the predictions by previous studies. We further observed that the magnetopause continued to remove electrons from the belt while electrons were simultaneously accelerated by fluctuations in the geomagnetic field. This is significant because electrons may be removed from the belt soon after they were created, limiting the overall growth of the radiation belt while the magnetopause was compressed. Key Points: Multimission phase space density observations are necessary to resolve relativistic electron dynamics during September 2017 stormRelativistic electron losses to the magnetopause were identified, which led to further diffusion of electrons toward the magnetopauseElectron loss to the magnetopause was observed simultaneous to prompt local energization in the heart of the radiation belt [ABSTRACT FROM AUTHOR]

Energetic particle fluxes in the outer magnetosphere present a significant challenge to modeling efforts as they can vary by orders of magnitude in response to solar wind driving conditions. In this study, we demonstrate the ability to propagate test particles through global magnetohydrodynamic (MHD) simulations to a high level of precision and use this to map the cross‐field radial transport associated with relativistic electrons undergoing drift orbit bifurcations (DOBs). The simulations predict DOBs primarily occur within an Earth radius of the magnetopause loss cone and appear significantly different for southward and northward interplanetary magnetic field orientations. The changes to the second invariant are shown to manifest as a dropout in particle fluxes with pitch angles close to 90° and indicate DOBs are a cause of butterfly pitch angle distributions within the night‐time sector. The convective electric field, not included in previous DOB studies, is found to have a significant effect on the resultant long‐term transport, and losses to the magnetopause and atmosphere are identified as a potential method for incorporating DOBs within Fokker‐Planck transport models. Key Points: We develop high precision test particle simulations integrated inside global magnetohydrodynamic simulations and study drift orbit bifurcationsThe resulting transport displays notable structure close to the magnetopause and differences for southward and northward interplanetary magnetic field orientationsThe convection electric field not included in previous DOB studies has a significant effect on the resultant transport characteristics [ABSTRACT FROM AUTHOR]

The magnetopause marks the outer edge of the Earth's magnetosphere and a distinct boundary between solar wind and magnetospheric plasma populations. In this study, we use global magnetohydrodynamic simulations to examine the response of the terrestrial magnetopause to fast‐forward interplanetary shocks of various strengths and compare to theoretical predictions. The theory and simulations indicate the magnetopause response can be characterized by three distinct phases; an initial acceleration as inertial forces are overcome, a rapid compressive phase comprising the majority of the distance traveled, and large‐scale damped oscillations with amplitudes of the order of an Earth radius. The two approaches agree in predicting subsolar magnetopause oscillations with frequencies 2–13 mHz but the simulations notably predict larger amplitudes and weaker damping rates. This phenomenon is of high relevance to space weather forecasting and provides a possible explanation for magnetopause oscillations observed following the large interplanetary shocks of August 1972 and March 1991. Plain Language Summary: The Earth's magnetic field carves out an approximately spherical region of space called a magnetosphere which charged particles streaming from the Sun are unable to directly penetrate. In this study we use computer simulations and theory to examine how the edge of the magnetosphere, the magnetopause, moves following the impact of interplanetary shock waves originating at the Sun. These shocks act to shift the magnetopause to a more tightly compressed position and we find that the magnetopause notably features large‐scale oscillations of decreasing magnitude before settling into a new stable location. When very large shock waves strike, the magnetopause can be compressed inside geosynchronous orbits and will therefore expose telecommunication satellites to increased radiation levels in the solar wind. These results provide an explanation for periodic magnetopause motion observed when large shock waves struck the Earth in August 1972 and in March 1991. Key Points: The response of the terrestrial magnetopause to fast‐forward interplanetary shocks is studied using theory and global magnetohydrodynamic simulationsTheory and simulations predict large‐scale damped oscillations with amplitudes up to an Earth radius and frequencies 2–13 mHzThis phenomenon may explain magnetopause oscillations observed following the large interplanetary shocks of August 1972 and March 1991 [ABSTRACT FROM AUTHOR]

Under periods of strong solar wind driving, the magnetopause can become compressed, playing a significant role in draining electrons from the outer radiation belt. Also termed "magnetopause shadowing," this loss process has traditionally been attributed to a combination of magnetospheric compression and outward radial diffusion of electrons. However, the drift paths of relativistic electrons and the location of the magnetopause are usually calculated from statistical models and, as such, may not represent the time‐varying nature of this highly dynamic process. In this study, we construct a database ∼20,000 spacecraft crossings of the dayside magnetopause to quantify the accuracy of the commonly used Shue et al. (1998, https://doi.org/10.1029/98JA01103) model. We find that, for the majority of events (74%), the magnetopause model can be used to estimate magnetopause location to within ±1 RE. However, if the magnetopause is compressed below 8 RE, the observed magnetopause is greater than 1 RE inside of the model location on average. The observed magnetopause is also significantly displaced from the model location during storm sudden commencements, when measurements are on average 6% closer to the radiation belts, with a maximum of 42%. We find that the magnetopause is rarely close enough to the outer radiation belt to cause direct magnetopause shadowing, and hence rapid outward radial transport of electrons is also required. We conclude that statistical magnetopause parameterizations may not be appropriate during dynamic compressions. We suggest that statistical models should only be used during quiescent solar wind conditions and supplemented by magnetopause observations wherever possible. Key Points: Measured magnetopause location is statistically closer to the Earth than Shue et al. (1998) modeled for storm sudden commencements (SYM‐H ≥15 nT)When the magnetopause is compressed below 8 RE, the average measured location is >1 RE inside of the Shue et al. (1998) model locationExtreme magnetopause compressions rarely reach the outer radiation belt, therefore rapid outward radial transport is required to fully explain most shadowing events [ABSTRACT FROM AUTHOR]

Twenty-two anorgasmic women received 20 sessions of a multiple-technique behavioural therapy. The design included blind ratings by two independent assessors, multiple assessment instruments, and a waiting list control group. Treatment was significantly better than no treatment in terms of: (1) the percentage of patients experiencing orgasm during at least 50 per cent of sexual relations; (2) the percentage of women reporting satisfactory sexual relations at least 50 per cent of the time; (3) patients' ratings of positive reactions to various sexual behaviours; and (4) assessors' global clinical ratings. Significant improvement was also noted on the MMPI, IPAT, and Symptom Check List. Improvement was maintained at a follow-up average 9 months later. These results support the impression that a behavioural approach offers much promise in treating female orgasmic dysfunction. [ABSTRACT FROM AUTHOR]