Magnetospheric Models and Trajectory Computations

Smart, D. F.; Shea, M. A.; Flückiger, E. O.

doi:10.1007/978-94-017-1187-6_15

Cited by 79 publications

(103 citation statements)

References 46 publications

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“…Several models, tools, algorithms to calculate geomagnetic cut-off rigidity, particle trajectories and the asymptotic viewing cones were proposed during the years (McCracken et al 1962(McCracken et al , 1968Shea et al 1965;Smart et al 2000). As the internal field we consider the IGRF geomagnetic model, which is a Gauss spherical harmonic model of the geomagnetic field, based on magnetic field measurements from geomagnetic stations, magnetometers and satellites (Langel 1987).…”

Section: Model Of the Earth Magnetospherementioning

confidence: 99%

Numerical model for computation of effective and ambient dose equivalent at flight altitudes

Mishev

Usoskin

2015

J. Space Weather Space Clim.

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A numerical model for assessment of the effective dose and ambient dose equivalent produced by secondary cosmic ray particles of galactic and solar origin at commercial aircraft altitudes is presented. The model represents a full chain analysis based on ground-based measurements of cosmic rays, from particle spectral and angular characteristics to dose estimation. The model is based on newly numerically computed yield functions and realistic propagation of cosmic ray in the Earth magnetosphere. The yield functions are computed using a straightforward full Monte Carlo simulation of the atmospheric cascade induced by primary protons and a-particles and subsequent conversion of secondary particle fluence (neutrons, protons, gammas, electrons, positrons, muons and charged pions) to effective dose or the ambient dose equivalent. The ambient dose equivalent is compared with reference data at various conditions such as rigidity cut-off and level of solar activity. The method is applied for computation of the effective dose rate at flight altitude during the ground level enhancement of 13 December 2006. The solar proton spectra are derived using neutron monitor data. The computation of the effective dose rate during the event explicitly considers the derived anisotropy i.e. the pitch angle distribution as well as the propagation of the solar protons in the magnetosphere of the Earth.

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Section: Model Of the Earth Magnetospherementioning

confidence: 99%

Numerical model for computation of effective and ambient dose equivalent at flight altitudes

Mishev

Usoskin

2015

J. Space Weather Space Clim.

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“…The computed trajectory is regarded as allowed (A), if it crosses the magnetospheric boundary, and as forbidden (F), if the trajectory rests on the Earth's surface, or trapped, if it remains within the magnetosphere for a long time. Progress of cosmic-ray trajectory computations in the geomagnetic fields has been summarized recently in [3]. Between the allowed and forbidden ranges of particle's rigidity, there is an area of complicated intermittent structure, the penumbra.…”

Section: Introductionmentioning

confidence: 99%

On Magnetospheric Transmissivity of Cosmic Rays

Kudela

Usoskin

2004

Czechoslovak Journal of Physics

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Results of computations of cosmic-ray trajectories in the model magnetic field obtained for a high-latitude neutron-monitor station (Oulu) and a middle-latitude one (Lomnický Stít) are summarized. The method is slightly different from previous computations by controlling the smoothness of the trajectory. At the lowest rigidity edge of allowed trajectories for Oulu (above the atmospheric cut-off), the external field and the addition of Dst shows variations of the asymptotic directions with the level of geomagnetic activity and with local time of observations. The transmissivity function introduced here, accounting for variability of the magnetic field with changing Kp and with local time, may be used as a reference for description of the average magnetospheric transparency at middle latitudes and it is probably better approximation than IGRF only. There are indications of appearance of windows of allowed trajectories at very low rigidities in the middle latitudes at 500 km (altitude of, e.g., CORONAS satellites or ISS) during the geomagnetic disturbance which is not the case for trajectories computed from the ground. : 96.40.Kk, 95.85.Ry PACS

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“…Here the electric field is ignored. Following Smart et al (2000) we calculate charged particle trajectories time-backwards with some rigidity at some position on Earth. If a particle can reach the boundary of magnetosphere before its total trajectory path length exceeds 1000 R E , the rigidity is considered an allowed rigidity (Kress et al, 2004).…”

Section: Models and Methodsmentioning

confidence: 99%

“…The step size in time is set to be equal to 0.01 of particles' gyro-period throughout the trajectory (Kress et al, 2004). The x, y, z coordinates are applicable when using the magnetospheric coordinates which are right handed, orthogonal, Earth centered coordinate systems (Smart et al, 2000). The coordinates we use here are the GEO (geographic coordinate system) and GSM (geocentric solar-magnetospheric).…”

Section: Models and Methodsmentioning

confidence: 99%

“…However, precise knowledge of energetic particles in the magnetosphere becomes more and more important for the security of spacecraft and astronauts. Recently, Smart and Shea did a series of studies (Smart, 1999;Smart et al, 2000;Shea and Smart, 2001;Smart andShea, 2003a, 2005) to determine the geomagnetic cutoff rigidities from charged particles trajectories by numerically solving Newton's equation of motion. This method is very accurate for calculating cosmic ray cutoff rigidities as long as the magnetospheric field is accurate enough and large-scale computer power is available.…”

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confidence: 99%

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The geomagnetic cutoff rigidities at high latitudes for different solar wind and geomagnetic conditions

Chu

Qin

2016

Ann. Geophys.

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Abstract. Studying the access of the cosmic rays (CRs) into the magnetosphere is important to understand the coupling between the magnetosphere and the solar wind. In this paper we numerically studied CRs' magnetospheric access with vertical geomagnetic cutoff rigidities using the method proposed by Smart and Shea (1999). By the study of CRs' vertical geomagnetic cutoff rigidities at high latitudes we obtain the CRs' window (CRW) whose boundary is determined when the vertical geomagnetic cutoff rigidities drop to a value lower than a threshold value. Furthermore, we studied the area of CRWs and found out they are sensitive to different parameters, such as the z component of interplanetary magnetic field (IMF), the solar wind dynamic pressure, AE index, and Dst index. It was found that both the AE index and Dst index have a strong correlation with the area of CRWs during strong geomagnetic storms. However, during the medium storms, only AE index has a strong correlation with the area of CRWs, while Dst index has a much weaker correlation with the area of CRWs. This result on the CRW can be used for forecasting the variation of the cosmic rays during the geomagnetic storms.

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Magnetospheric Models and Trajectory Computations

Cited by 79 publications

References 46 publications

Numerical model for computation of effective and ambient dose equivalent at flight altitudes

Numerical model for computation of effective and ambient dose equivalent at flight altitudes

On Magnetospheric Transmissivity of Cosmic Rays

The geomagnetic cutoff rigidities at high latitudes for different solar wind and geomagnetic conditions

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