220 research outputs found
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Pro‐ L * ‐ A probabilistic L * mapping tool for ground observations
Both ground and space observations are used extensively in the modeling of space weather processes within the Earth's magnetosphere. In radiation belt physics modeling, one of the key phase‐space coordinates is L*, which indicates the location of the drift paths of energetic electrons. Global magnetic field models allow a subset of locations on the ground (mainly sub‐auroral) to be mapped along field lines to a location in space and transformed into L*, provided that the initial ground location maps to a closed drift path. This allows observations from ground, or low‐altitude space‐based platforms to be mapped into space in order to inform radiation belt modeling. Many data‐based magnetic field models exist; however these models can significantly disagree on mapped L* values for a single point on the ground, during both quiet times and storms. We present a state of the art probabilistic L* mapping tool, Pro‐L*, which produces probability distributions for L* corresponding to a given ground location. Pro‐L* has been calculated for a high resolution magnetic latitude by magnetic local time (MLT) grid in the Earth's northern hemisphere. We have developed the probabilistic model using 11 years of L* calculations for 7 widely used magnetic field models. Usage of the tool is highlighted for both event studies and statistical models, and we demonstrate a number of potential applications
Gradual diffusion and punctuated phase space density enhancements of highly relativistic electrons: Van Allen Probes observations
Abstract The dual-spacecraft Van Allen Probes mission has provided a new window into mega electron volt (MeV) particle dynamics in the Earth\u27s radiation belts. Observations (up to E ~10 MeV) show clearly the behavior of the outer electron radiation belt at different timescales: months-long periods of gradual inward radial diffusive transport and weak loss being punctuated by dramatic flux changes driven by strong solar wind transient events. We present analysis of multi-MeV electron flux and phase space density (PSD) changes during March 2013 in the context of the first year of Van Allen Probes operation. This March period demonstrates the classic signatures both of inward radial diffusive energization and abrupt localized acceleration deep within the outer Van Allen zone (L ~4.0 ± 0.5). This reveals graphically that both competing mechanisms of multi-MeV electron energization are at play in the radiation belts, often acting almost concurrently or at least in rapid succession. Key Points Clear observations to higher energy than ever before Precise detection of where and how acceleration takes place Provides new eyes on megaelectron Volt
Effect of EMIC waves on relativistic and ultrarelativistic electron populations: Ground-based and Van Allen Probes observations
Abstract We study the effect of electromagnetic ion cyclotron (EMIC) waves on the loss and pitch angle scattering of relativistic and ultrarelativistic electrons during the recovery phase of a moderate geomagnetic storm on 11 October 2012. The EMIC wave activity was observed in situ on the Van Allen Probes and conjugately on the ground across the Canadian Array for Real-time Investigations of Magnetic Activity throughout an extended 18 h interval. However, neither enhanced precipitation of \u3e0.7 MeV electrons nor reductions in Van Allen Probe 90° pitch angle ultrarelativistic electron flux were observed. Computed radiation belt electron pitch angle diffusion rates demonstrate that rapid pitch angle diffusion is confined to low pitch angles and cannot reach 90°. For the first time, from both observational and modeling perspectives, we show evidence of EMIC waves triggering ultrarelativistic (~2-8 MeV) electron loss but which is confined to pitch angles below around 45° and not affecting the core distribution. Key Points EMIC wave activity is not associated with precipitation of MeV electrons EMIC waves do not deplete the ultra-relativistic belt down to 90° EMIC waves cause loss of low pitch angle electrons with energies ~2-8 MeV
Evolution of the proton ring current energy distribution during 21–25 April 2001 storm
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95267/1/jgra18324.pd
Обґрунтування вибору малоінвазивних оперативних втручань при врослому нігті у хворих на цукровий діабет
The aim of the work: to give an example of the use of a minimally invasive method o f ARCADA in the treatment of onochryptosis.Цель работы: привести пример использования малоинвазивного метода ARCADA при лечении онихокриптоза у больных сахарным диабетом.Мета роботи: навести приклад використання малоінвазивного методу ARCADA при лікуванні оніхокриптозу у хворих на цукровий діабет
Preonset time sequence of auroral substorms: Coordinated observations by all‐sky imagers, satellites, and radars
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94777/1/jgra20852.pd
PENGUIn multi‐instrument observations of dayside high‐latitude injections during the 23 March 2007 substorm
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94875/1/jgra19563.pd
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