We review the morphology and dynamics of electrical current systems terrestrial magnetosphere ionosphere. Observations from Active Magnetosphere Planetary Electrodynamics Response Experiment (AMPERE) over three years 2010 to 2012 are employed illustrate variability field-aligned currents that couple ionosphere, on timescales minutes years, in response impact solar wind disturbances changes level illumination polar ionospheres. The is discussed within context occurrence magnetic reconnection...

We present a new quantitative technique that determines the times and durations of substorm expansion recovery phases possible growth based on percentiles rate change auroral electrojet indices. By being able to prescribe different percentile values, we can determine onset duration for smaller or larger variations index indeed any zone ground-based magnetometer data. apply this SuperMAG AL (SML) compare our phase with previous lists onsets. find more than 50% events in occur within 20 min...

The solar-wind magnetosphere interaction primarily occurs at altitudes where the dipole component of Earth’s magnetic field is dominating. disturbances that are created in this propagate along lines and interact with ionosphere–thermosphere system. At ionospheric altitudes, deviates significantly from a dipole. North–South asymmetries imply magnetosphere–ionosphere–thermosphere (M–I–T) coupling different two hemispheres. In paper we review primary differences polar latitudes, consequences...

We study the semi-annual variation in geomagnetic activity, as detected indices am , aa H AL Dst and four aσ derived for 6-hour MLT sectors (around noon, dawn, dusk midnight). For each we compare amplitude of variation, a fraction overall mean, to that corresponding power input magnetosphere, P α estimated from interplanetary observations. demonstrate is amplified data compared by factor different index. The largest amplification index (factor ~ 10) smallest noon sector ( -noon, ≈ 1.1). By...

We use current density data from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) to identify location of maximum region 1 at all magnetic local times (MLTs). term this R1 oval. Comparing oval with particle precipitation boundaries identified in DMSP data, we find that is located on average within 1° signatures associated open/closed field line boundary (OCB) across dayside nightside MLTs. hence conclude can be used as a proxy for OCB. Studying amount flux...

Abstract In this paper we present the first large‐scale statistical study of influence magnetic reconnection on magnitude regions 1 and 2 Birkeland field‐aligned currents (FACs). While previous studies have employed single spacecraft measurements to construct a picture location density currents, it has hitherto been difficult compare in situ solar wind with instantaneous global current measurements. To that end, utilize Active Magnetosphere Planetary Electrodynamics Response Experiment...

Abstract We present the first large‐scale comparison of spatial distribution field‐aligned currents as measured by Active Magnetosphere and Planetary Electrodynamics Response Experiment, with location brightness average auroral oval, determined from Imager for Magnetopause‐to‐Aurora Global Exploration far ultraviolet instrument. These distributions are compared under same interplanetary magnetic field magnitude clock angle conditions. The oval drop to lower latitudes, becomes both...

Abstract We perform a superposed epoch analysis of the evolution Birkeland currents (field‐aligned currents) observed by Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) during substorms. The study is composed 2900 substorms provided SuperMAG experiment. find that current ovals expand contract over course substorm cycle increase in magnitude approaching onset are further enhanced expansion phase. Subsequently, we categorize their latitude, proxy for amount open...

Substorms are fundamental and dynamic processes in the magnetosphere, converting captured solar wind magnetic energy into plasma energy. These substorms have been suggested to be a key driver of energetic electron enhancements outer radiation belts. inject keV "seed" population inner magnetosphere which is subsequently energized through wave-particle interactions up relativistic energies; however, extent enhance belts, either directly or indirectly, has never before quantified. In this...

We reduce measurements made by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) to give total Birkeland (field-aligned) current flowing in both hemispheres monthly hourly bins. analyze these totals using 6 years of data (2010-2015) examine solar zenith angle-driven variations hemispheres, simultaneously, for first time. A diurnal variation is identified flowing, consistent with angle. seasonal also identified, more Northern (Southern) Hemisphere during...

Abstract Flux transfer events are bursts of reconnection at the dayside magnetopause, which give rise to characteristic signatures observed by a range magnetospheric/ionospheric instrumentation. One outstanding problem is that there fundamental mismatch between space‐based and ionospheric estimates flux opened each event—in other words, their overall significance in Dungey cycle. Spacecraft‐based content individual (FTEs) correspond event transferring equivalent approximately 1% open...

This is the second in a series of papers that investigate semi-annual, annual and Universal Time ( UT ) variations magnetosphere. We present varied collection empirical results can be used to constrain theories modelling these variations. An initial study two years’ data on transpolar voltage shows there semi-annual variation magnetospheric flux circulation; however, it not as large amplitude geomagnetic activity, consistent with latter showing non-linear (quadratic) voltage. find during...

A key component of solar wind-magnetosphere-ionosphere coupling manifests in the high-latitude field-aligned currents and spatial extent open magnetic flux polar cap. This turn drives changes cross-polar cap potential (CPCP), like saturation under extreme conditions, dynamics ionospheric electric field, over- or under-shielding at sub-auroral latitudes. While there have been many studies linking wind interplanetary field (IMF) driving conditions with change area, interhemispheric differences...

Space weather describes the dynamic conditions in near-Earth space, mostly driven by variable interaction between continuous flow of solar wind and Earth’s magnetic field.  Extreme space has potential to disrupt or damage key infrastructure on which we rely, for example through generation large, anomalous Geomagnetically Induced Currents (GICs) power networks transformers.  Accurately forecasting a risk large GICs would enable actions be taken mitigate their...

Abstract Using the location of maximum region 1 current determined by Active Magnetosphere and Planetary Electrodynamics Response Experiment as a proxy for open/closed field line boundary, we monitor evolution amount open magnetic flux inside magnetosphere during 772 substorms. We then divide all substorms into three classes, depending on at expansion phase onset. Studying temporal variations each class number related geophysical parameters, find that occurring while is large are generally...

Abstract High‐latitude ionospheric convection is a useful diagnostic of solar wind‐magnetosphere interactions and nightside activity in the magnetotail. For decades, high‐latitude pattern has been mapped using Super Dual Auroral Radar Network (SuperDARN), distribution ground‐based radars which are capable measuring line‐of‐sight (l‐o‐s) flows. From l‐o‐s measurements an estimate global can be obtained. As SuperDARN coverage not truly global, it necessary to constrain maps when map fitting...

Equitable Letters in Space and Physics (ELSP) is an organization that aims to encourage merit-based recommendations nominations the space physics community by providing resources reviews. Recommendation award nomination letters are a known source of bias affect education job opportunities, career progression, recognition for scientists from underrepresented backgrounds.  ELSP was founded combat this within current system proof-reading service focuses on identifying phrasing...

We employ ground magnetometers in North America, Greenland, and Antarctica use the Spherical Elementary Current (SEC) technique order to investigate Birkeland currents (also known as field-aligned currents) flowing between January 2015 December 2016. convert measurements into altitude-adjusted corrected geomagnetic (AACGM) coordinates, then average across each day for which we have data obtain global maps both Northern Southern Hemispheres period question. examine systematic asymmetry by...

Abstract We examine the statistical distribution of large‐scale Birkeland currents measured by Active Magnetosphere and Planetary Electrodynamics Response Experiment in four unique categories geomagnetic activity for first time: quiet times, storm quiet‐time substorms, storm‐time substorms. A novel method is employed to sort data into one these categories, categorizations are provided future research. The mean current density largest during substorms its standard deviation storms. Current...

Abstract We conduct a superposed epoch analysis of Birkeland current densities from AMPERE (Active Magnetosphere and Planetary Electrodynamics Response Experiment) using isolated substorm expansion phase onsets identified by an independently derived data set. In order to evaluate whether R1 R2 currents contribute the wedge, we rotate global maps into common coordinate system centered on magnetic local time onset. When latitude is taken account, it clear that both systems play role in onset,...

Abstract Field‐aligned currents (FACs), also known as Birkeland currents, are the agents by which energy and momentum transferred to ionosphere from magnetosphere solar wind. This coupling is enhanced at substorm onset through formation of current wedge. Using FAC data Active Magnetosphere Planetary Electrodynamics Response Experiment expansion phase onsets identified using Substorm Onsets Phases Indices Electrojet technique, we examine Northern Hemisphere FACs in all local time sectors with...

Abstract We obtain current densities from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE), alongside B y z Interplanetary Magnetic Field (IMF) for March 2010. For each AMPERE spatial coordinate, we cross‐correlate density with , finding maximum correlation lags up to 360 min. The patterns of contain large‐scale structures consistent literature. on dayside are 10 min at high latitudes but 240 lower latitudes. Lags nightside 90–150 shortest 10–20 min;...

This is the third in a series of papers that investigate semi-annual, annual and Universal Time variations magnetosphere. In this paper, we use Lin et al. (2010) empirical model magnetopause locations, along with assumption pressure equilibrium Newtonian approximation magnetosheath pressure, to show equinoctial pattern arises both cross-tail current at tail hinge point total energy stored tail. The allows us study effects dipole tilt hemispheric asymmetries. As test necessary assumptions...