The dipole configuration of the Earth's magnetic field allows for trapping highly energetic particles, which form radiation belts. Although significant advances have been made in understanding acceleration mechanisms belts, loss processes remain poorly understood. Unique observations on 17 January 2013 provide detailed information throughout belts energy spectrum and pitch angle (angle between velocity a particle field) distribution electrons up to ultra-relativistic energies. Here we show...

Plasmaspheric drainage plumes are regions of dense plasma that extend outward from the plasmasphere into outer magnetosphere. We present observations for two events, 2 June 2001 and 26–27 2000. Our come sources. A global perspective is provided by IMAGE extreme ultraviolet (EUV) imager, which routinely obtains images helium portion above total densities 30–50 e − cm −3 . Simultaneous in situ plasmaspheric obtained Magnetospheric Plasma Analyzer (MPA) instruments onboard Los Alamos National...

Global images of the plasmasphere obtained by Extreme Ultraviolet (EUV) imager on IMAGE satellite are used to study evolving structure during two geomagnetic disturbances. By tracking location plasmapause as a function L shell and magnetic local time, quantitative measurements radial azimuthal motions boundary made for intervals ≥7 hours in duration with time resolution 10 min. The cases presented 26–27 June 2001, relatively weak but isolated disturbance, 9–10 moderate event multistaged...

Remote sensing of the entire plasmasphere is routinely accomplished by Extreme Ultraviolet (EUV) imager on IMAGE satellite. EUV observes helium distribution in detecting resonantly scattered solar 30.4‐nm ultraviolet radiation. In images plasmapause assumed to be “ He + edge,” i.e., outermost sharp edge where brightness emissions drops abruptly. This assumption verified comparing L ‐shell steep electron density gradients, extracted from passive mode dynamic spectrograms recorded Radio Plasma...

Detached dayside proton arcs have been recently observed at Earth with the IMAGE FUV instrument as subauroral separated from main oval and extending over several hours of local time in afternoon sector. We investigate mechanisms causing precipitation during two arc events that occurred on 23 January 2001 18 June 2001. employ our kinetic physics‐based model coupled a dynamic plasmasphere calculate growth rate electromagnetic ion cyclotron (EMIC) waves self‐consistently evolving ring current H...

Abstract Plasmaspheric hiss is a whistler‐mode emission that permeates the Earth's plasmasphere and significant driver of energetic electron losses through cyclotron resonant pitch angle scattering. The Electric Magnetic Field Instrument Suite Integrated Science instrument on Van Allen Probes mission provides vastly improved measurements wave environment including continuous magnetic field cross‐spectral matrix enhanced low‐frequency coverage. Here, we develop empirical models intensity...

Abstract We present the Neural‐network‐based Upper hybrid Resonance Determination (NURD) algorithm for automatic inference of electron number density from plasma wave measurements made on board NASA's Van Allen Probes mission. A feedforward neural network is developed to determine upper resonance frequency, f uhr , electric field measurements, which then used calculate density. In previous missions, bands were manually identified, and there have been few attempts do robust, routine automated...

Abstract The Electric and Magnetic Field Instrument Suite Integrated Science (EMFISIS) instrument on the Van Allen Probes provides a vast quantity of fully resolved wave measurements below L = 5.5, critical region for radiation belt acceleration loss. EMFISIS data show that plasmaspheric hiss waves can be observed at frequencies as low 20 Hz provide three‐component magnetic field directly used electron scattering calculations. Updated models properties based statistical analysis were...

Using data from the CRRES plasma wave experiment, we develop quadratic fits to mean of amplitude squared for plasmaspheric hiss as a function Kp, L, and magnetic latitude (λ) dayside (6 < local time (MLT) ≤ 21) nightside (21 MLT 6) sectors. The empirical model waves is used compute quasi-linear pitch angle diffusion coefficients energetic, relativistic, ultrarelativistic electrons in energy range 1 keV 10 MeV. In our calculations, account changes normal density with increasing λ. Electron...

Abstract We present the PINE (Plasma density in Inner magnetosphere Neural network‐based Empirical) model ‐ a new empirical for reconstructing global dynamics of cold plasma distribution based only on solar wind data and geomagnetic indices. Utilizing database obtained using NURD (Neural‐network‐based Upper hybrid Resonance Determination) algorithm period 1 October 2012 to July 2016, conjunction with indices, we develop neural network that is capable globally 2≤ L ≤6 all local times....

Observations of detached subauroral proton arcs by the FUV instrument on IMAGE spacecraft have been recently reported and shown to be produced ring current ions precipitating in afternoon local time sector during geomagnetically disturbed periods. Data from June 18, 2001 show a direct link between arc global observation plasmaspheric plume EUV instrument. Using T96 magnetic field model, maps broad region enhanced cold plasma density associated with plume. The suggests that precipitation may...

Using data from the High Frequency Waveform Receiver on board Polar spacecraft, 1,765 and 993 wave normal angles have been analyzed for 13 orbits containing upper band magnetospheric chorus emissions 15 lower emissions, respectively. The purpose of this study is to characterize distribution polar angle, θ, as a function magnetic latitude, λ . Understanding an important step in evaluating resonant wave‐particle interactions. For chorus, tend remain at or rise toward resonance cone angle low...

Accurate models of trans‐ionospheric propagation are needed to assess the role Earth‐originating very low frequency (VLF) electromagnetic waves in radiation belt dynamics. Recent studies have called relatively crude early into question, finding that they underestimate attenuation by 20–100 dB. A full wave model includes all relevant physics has recently become available and experimentally verified within a few decibels via comparison more extensive satellite data. Using this model, we...

Abstract We investigate the temporal evolution and spatial distribution of electromagnetic ion cyclotron (EMIC) waves during 8–11 June 2001 geomagnetic storm, one storms selected for study by Geospace Environment Modeling program. Generations EMIC in H + , He O bands are simulated using kinetic ring current‐atmosphere interactions model with a self‐consistent magnetic field ray tracing code. Simulations show that strong wave gain occurs afternoon sector at L &gt; 5 overlaps high‐density...

Using ELF/VLF wave data recorded in 2007 from two high‐latitude (Λ = 69.8°, 71.8°) Antarctic ground stations, the dayside variation of chorus occurrence and amplitude are analyzed conjunction with geomagnetic solar wind driving parameters. Both stations observe (defined here as discrete rising emission tones together unstructured hiss) a broad window local time across when on closed magnetic field lines. Wave rates rise rapidly ∼0.06–0.12 at dawn to their maximum value ∼0.5–0.6 near noon....

Among the objectives of Radio Plasma Imager (RPI) on IMAGE is observation Earth's plasmasphere from satellite's polar orbit, with apogee ≈8 R E geocentric distance and perigee near 1200 km altitude. This objective here pursued by (1) remote sounding high‐altitude regions outside main plasmasphere, (2) within (3) in situ passive measurements natural wave activity. During both inside plasmapause, RPI echoes that follow non‐field‐aligned ray paths are usually not discrete traces...

The temporal evolution of afternoon sector proton precipitation observed by a global auroral imager is examined in detail for two case events. We focus on regions that are magnetically mapped to the plasmapause and plasmaspheric plume regions. spatial variation plume‐associated precipitation, including its relationship main oval, dependent prevailing solar wind magnetospheric driving conditions. Two contrasting events presented here association with 1) substorm injection 2) northward IMF...

We perform a case study of conjugate observations whistler mode chorus waves on the dayside made 26 July 2008 by three THEMIS spacecraft and ground‐based ELF/VLF receivers at Automatic Geophysical Observatories (AGO) in Antarctica supported U.S. Polar Experiment Network for Geospace Upper‐atmosphere Investigations (PENGUIn) project. The were excited during period no substorm activity with geomagnetic indices indicating quiet conditions (Dst ∼ −10 nT; AE &lt; 200 nT). solar wind dynamic...

We have analyzed ELF‐VLF receiver and search coil magnetometer data from five Antarctic stations 1998 1999 to study quasiperiodic emissions (QPs) periodic (PEs), which occur as ULF‐range modulations of signals between 0.5 kHz ∼4 kHz. QPs are modulated at frequencies ∼20–50 mHz, PEs ∼200–500 mHz. The used covered a range magnetic latitudes −62° (Halley) −74° (South Pole Station); three automated geophysical observatories (AGOs) were located intermediate latitudes. Consistent with earlier...

Determining the global distribution of chorus wave power in off‐equatorial region (i.e., magnetic latitude λ &gt; 15°) is a crucial component understanding contribution to radiation belt acceleration and loss. In this paper we use database spectral density observations from Plasma Wave Instrument (PWI) Sweep Frequency Receiver (SFR) on Polar spacecraft generate separate distributions occurrence rate field amplitude as function space geomagnetic activity. Previous studies focused...

Intense electromagnetic ion cyclotron (EMIC) waves are observed within plasmaspheric plumes during geomagnetic storms and believed to be a significant driver of loss both ring current protons radiation belt electrons. In this study, we use ray tracing together with path‐integrated linear growth calculations analyze the amplification propagation EMIC cold plasma density irregularities characteristic plume. All launched at equator in range L = 5 7, wave is analyzed as function frequency...