RADIATION HAZARD ON EARTH AND IN NEAR-EARTH SPACE DURING MAGNETIC FIELD INVERSION

Recent observations, such as the magnetic field strength decrease, a magnetic poles shifts and the South Atlantic anomaly increase, may indicate the beginning of the Earth’s magnetic field inversion. According to the geomagnetic dynamo model, the dipole component of the magnetic field is zeroed at the inversion time, and the quadrupole one becomes dominant. To assess the occurrence of radiation hazards on the Earth’s surface and in near-Earth space at the time of magnetic field inversion, a numerical model was developed that made it possible to compare the GCR and SCR fluxes (at minima and maxima of solar activity) penetrating the Earth (taking into account the atmosphere) and the ISS in periods of the dipole and quadrupole fields dominance. It was found that during the period of inversion the flow of GCR (high-energy particles) can increase no more than three times over the entire surface of the Earth and the radiation dose will not exceed permissible one for man. Also, a change of the magnetic field configuration will redistribute areas of increased radiation on the Earth’s surface (today these are the poles of the Earth), which can adversely affect people’s health in these areas.

Download Full-text

Earth inner drift shells as observed by the Advanced Stellar Compass on Swarm

10.5194/egusphere-egu2020-22239 ◽

2020 ◽

Author(s):

Jose M G Merayo ◽

John L Joergensen ◽

Peter S Joergensen ◽

Matija Herceg ◽

Mathias Benn ◽

...

Keyword(s):

Magnetic Field ◽

Magnetic Field Gradient ◽

Minimum Energy ◽

Rotation Period ◽

High Energy ◽

High Energy Particle ◽

Flux Transport ◽

The Earth ◽

The Magnetic Field ◽

East West

Since launch in November 2013, the Swarm constellation of three satellites provides detailed measurements of the magnetic field of the Earth. To ensure the high accuracy of magnetic vector observation by Vector Field Magnetometer (VFM), the Swarm inertial attitude is determined by the micro Advanced Stellar Compass (&#956;ASC). Besides its primary function of attitude determination, the &#181;ASC is also capable of detecting particles with energies high enough to penetrate its camera shielding, where particles passing the focal plane CCD detector leave detectable ionization tracks. The typical shielding employed requires the minimum energy to penetrate >15MeV for electrons, > 80MeV for protons and >~GeV for heavier elements.The signature of passing particle will only persist in one frame time, but the signature differs between electrons and protons. To ensure full attitude performance operations even during the most intense CMEs, the signatures are removed before star tracking. By counting the signatures, and using a model for the flux transport through the shielding, an accurate measure of the instantaneous high energy particle flux is achieved at each update cycle (250ms).With this feature installed on all three Swarm spacecrafts, a hitherto unprecedented accurate mapping of the proton population around Earth is achieved at two distances, 450 and 530km.The superrelativistic protons measured by the &#956;ASC (g>>1), travel at speeds very close to c, and bouncing between the North and South Earth sphere, encounters complex field structures for at least some of the time. The bounce period is much smaller than the Earth rotation period, and an east-west drift component is caused by the magnetic field gradient.We will present observations of the trapped proton fluxes and show how the magnetic field affects their motion shells. Slightly deformed particle drift shells due to the magnetic field structure (for orbits with L>1.07) and the differential east-west drift as measured by the Swarm Alpha and Charlie satellites will be discussed.

Download Full-text

On the radiation emitted by a fast charged particle in the magnetic field

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1948.0007 ◽

1948 ◽

Vol 192 (1029) ◽

pp. 231-246 ◽

Cited By ~ 1

Keyword(s):

Magnetic Field ◽

High Energy ◽

Cascade Process ◽

The Earth ◽

Main Effect ◽

Shower Maximum ◽

Very High Energy ◽

The Magnetic Field ◽

Very High ◽

Fast Charged Particle

Pomeranchuk has shown that electrons with energies ⪢ 10 17 eV passing through the earth’s magnetic field lose most of their energies. It is shown in this paper that the energy lost is transformed into some 600 photons of very high energy. These photons are distributed along a very narrow band of several decimetres or even only several centimetres length. The magnetic field of the earth can influence appreciably neither the energy spectrum nor the spread of extensive showers. Its main effect consists in shifting the shower maximum to a higher altitude. Something like the cascade process might be developed by a very fast electron before it reaches the top of the atmosphere.

Download Full-text

MAGNETIC FIELD REVERSALS OF THE EARTH: A TWO–DISK RIKITAKE DYNAMO MODEL

International Journal of Modern Physics B ◽

10.1142/s0217979209063808 ◽

2009 ◽

Vol 23 (28n29) ◽

pp. 5492-5503 ◽

Cited By ~ 1

Author(s):

SANDRO DONATO ◽

DOMENICO MEDURI ◽

FABIO LEPRETI

Keyword(s):

Magnetic Field ◽

Laboratory Experiments ◽

Dynamo Model ◽

The Sun ◽

The Earth ◽

Simulation Based ◽

Dynamical Regimes ◽

Polarity Reversals ◽

Disk Dynamo ◽

The Magnetic Field

The Sun and the Earth possess dipolar magnetic fields that exhibit polarity reversals. Recent works, based on numerical simulations and laboratory experiments, found similar dynamical behaviours. We present results of a statistical analysis of a numerical simulation based on a generalized two–disk dynamo model. From a first investigation, we found that the dynamics of the system is controlled by the variations of the ratio of the torques and we observed different dynamical regimes characterized either by bursts or reversals, which can be periodic or random, of the magnetic field.

Download Full-text

Method of Wavelet-Decomposition to Research Cosmic Ray Variations: Application in Space Weather

Symmetry ◽

10.3390/sym13122313 ◽

2021 ◽

Vol 13 (12) ◽

pp. 2313

Author(s):

Oksana Mandrikova ◽

Bogdana Mandrikova

Keyword(s):

Cosmic Rays ◽

Space Weather ◽

Outer Space ◽

Cosmic Ray ◽

High Energy ◽

Radiation Hazard ◽

Interstellar Space ◽

Radio Communication ◽

Earth Space ◽

Near Earth Space

Since their discovery, cosmic rays have been an integral part of the development of fundamental physics, from the discovery of radiation coming to the Earth from outer space and the identification of high-energy particles in it, as well as new fundamental symmetries in the laws of nature, to the knowledge of residual matter and magnetic fields in interstellar space. Cosmic rays are used in a number of fundamental and applied research in solar-terrestrial physics and are important in the research of the near-Earth space processes. Cosmic ray variations observed on the Earth’s surface are an integral result of various solar, heliospheric, magnetospheric and atmospheric phenomena. The most significant changes in cosmic ray parameters are caused by coronal mass ejections and subsequent changes in the parameters of the interplanetary magnetic field and solar wind. Therefore, the study of cosmic rays makes it possible to obtain valuable information about the processes in the near-Earth space and in the Earth’s magnetosphere during disturbed periods. This article proposes a method for analyzing cosmic ray variations. It is based on the use of wavelet data decomposition operations and their combination with threshold functions. By using adaptive thresholds, the operations for detecting anomalous changes in data and for suppressing the noise were developed. Anomalies in cosmic rays can cause radiation hazard for astronauts, radio communication failures, as well as malfunctions in satellites, leading to the loss of orientation and destruction. Therefore, the task of timely diagnostics of anomalies is urgent. The paper describes the algorithms for the implementation of the method and shows their application in the space weather problem. We used data from the network of ground stations of neutron monitors. The efficiency of the method for detecting abnormal changes of different amplitudes and durations is shown. Application of the method made it possible to detect clearly and to evaluate Forbush effects in cosmic rays, which precede the onset of magnetic storms of various nature and strength.

Download Full-text