COSMIC RAY CUTOFF RIGIDITY CHANGES CAUSED BY THE DISTURBED GEOMAGNETIC FIELD OF THE STORM IN JUNE 2015 AND THEIR RELATION WITH THE INTERPLANETARY AND SOLAR WIND PARAMETERS

Vertical cutoff rigidities have been calculated for a world grid 5 degrees in latitude and 15 degrees in longitude using the Finch and Leaton sixth-degree simulation of the quiescent geomagnetic field. These calculations utilized the trajectory-tracing procedure at intervals of 0.01 BV throughout the penumbral region to determine an "effective" vertical cutoff rigidity defined by Shea et al. (1965). When experimental cosmic-ray intensity data are plotted using threshold rigidities derived from this grid, greater coherence of these data is found than is obtained using previously published threshold values. However, small deviations from an intuitively pleasing smooth curve indicate we may have reached a limitation in the usefulness of vertical cutoff rigidities, and perhaps second-order effects should be included when using cutoff rigidity as a parameter in the analysis of very precise cosmic-radiation intensity data.

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Geomagnetic effects on cosmic ray propagation for different conditions

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312004899 ◽

2011 ◽

Vol 7 (S286) ◽

pp. 234-237

Author(s):

Jimmy J. Masías-Meza ◽

Xavier Bertou ◽

Sergio Dasso

Keyword(s):

Numerical Simulations ◽

Geomagnetic Activity ◽

Geomagnetic Field ◽

Cosmic Ray ◽

Cutoff Rigidity ◽

Lower Cutoff

AbstractThe geomagnetic field (Bgeo) sets a lower cutoff rigidity (Rc) to the entry of cosmic particles to Earth which depends on the geomagnetic activity. From numerical simulations of the trajectory of a proton (performed with the MAGCOS code) in the Bgeo, we use backtracking to analyze particles arriving at the Auger Observatory location. We determine the asymptotic trajectories and the values of Rc in different incidence directions. Simulations were done using several models of Bgeo that emulate different geomagnetic conditions.

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Variations of geomagnetic thresholds of cosmic rays and magnetospheric parameters during different phases of the storm of November 20, 2003

10.5194/egusphere-egu21-5480 ◽

2021 ◽

Author(s):

Elena Vernova ◽

Natalia Ptitsyna ◽

Olga Danilova ◽

Marta Tyasto

Keyword(s):

Solar Wind ◽

Cosmic Rays ◽

Hysteresis Loop ◽

Magnetic Storm ◽

Cosmic Ray ◽

Recovery Phase ◽

Main Phase ◽

Cutoff Rigidity ◽

The Relationship ◽

Current Systems

<div> <p>The correlations between variations in the geomagnetic cutoff rigidity of cosmic rays and the Dst and Kp geomagnetic indices and solar-wind and IMF parameters are calculated for the three phases of the magnetic storm of November 20&#8211;21, 2003: before the storm and during its main and recovery phases. The correlations are the strongest between variations in the cutoff rigidity and the Dst index during all stages. A significant correlation was recorded with the By component of IMF and the field magnitude B; the correlation with By dominated during the main phase, and the correlation with B was dominant during the recovery phase. There is also a high correlation with the dynamic parameters of solar activity during the main phase, especially with the solar-wind speed.</p> <div> <p>As far as we know, hysteresis phenomena have been discovered for the first time in the relationship between the cosmic-ray cutoff rigidities and the parameters of the helio- and magnetosphere on the scale of the magnetic storm (with Moscow station as an example). Loop-like patterns formed, because the trajectories of variations in the cutoff rigidities versus the studied parameters during storm intensification (development of current systems) did not coincide with the trajectories during the recovery phase (decay of current systems). The correlations of the cutoff rigidities with Dst and Kp indices were characterized by a narrow hysteresis loop, and their correlations with the IMF parameters were characterized by a wide hysteresis loop. The hysteresis loops for the relationship between the cutoff rigidities and solar-wind density and pressure were disordered.</p> </div> </div>

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Anomalous Forbush effects from sources far from Sun center

Proceedings of the International Astronomical Union ◽

10.1017/s1743921309029688 ◽

2008 ◽

Vol 4 (S257) ◽

pp. 451-456

Author(s):

E. Eroshenko ◽

A. Belov ◽

H. Mavromichalaki ◽

V. Oleneva ◽

A. Papaioannou ◽

...

Keyword(s):

Solar Wind ◽

Cosmic Ray ◽

The Sun ◽

Geomagnetic Disturbances ◽

Cosmic Ray Intensity ◽

The Earth ◽

The Common ◽

Solar Wind Parameters ◽

Significant Disturbance ◽

Forbush Effect

AbstractThe Forbush effects associated with far western and eastern powerful sources on the Sun that occurred on the background of unsettled and moderate interplanetary and geomagnetic disturbances have been studied by data from neutron monitor networks and relevant measurements of the solar wind parameters. These Forbush effects may be referred to a special sub-class of events, with the characteristics like the event in July 2005, and incorporated by the common conditions: absence of a significant disturbance in the Earth vicinity; absence of a strong geomagnetic storm; slow decrease of cosmic ray intensity during the main phase of the Forbush effect. General features and separate properties in behavior of density and anisotropy of 10 GV cosmic rays for this subclass are investigated.

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Patterns of Atmospheric 14C Changes

Radiocarbon ◽

10.1017/s0033822200009437 ◽

1980 ◽

Vol 22 (2) ◽

pp. 166-176 ◽

Cited By ~ 20

Author(s):

Minze Stuiver ◽

Paul D Quay

Keyword(s):

Solar Wind ◽

Geomagnetic Field ◽

Cosmic Ray ◽

Solar Modulation ◽

Production Rates ◽

Climatic Fluctuation ◽

The Past ◽

Earth Magnetic Field ◽

Carbon Reservoir ◽

Cosmic Ray Flux

Natural atmospheric 14C changes are caused by fluctuations in upper atmospheric 14C production rates (Q) that are related to earth geomagnetic field variations and changes in solar wind magnetic shielding properties. Climate variability may also be responsible for some of the changes because it influences exchange rates of 14C between the various terrestrial carbon reservoirs.Upper atmospheric 14C production rates QM, in at/sec cm2 (earth), were calculated for the past 1200 years from the atmospheric 14C record and a carbon reservoir model. The changes in QM are compared in detail with the predicted Q variability derived from an Aa solar modulation mechanism and 20th century neutron flux observations. The influence of earth geomagnetic field changes on the magnitude of the solar wind modulation is discussed, and it is shown that the variations in this magnitude agree with the known differences in earth magnetic field intensity during the past 1200 years. The larger calculated QM oscillations during the sixth millennium bp also agree with this concept.Solar wind magnetic as well as geomagnetic forces modulate the incoming cosmic ray flux and explain the main features of the atmospheric 14C record. It is argued that climatic fluctuation is not a dominant cause.The oscillations between 3200 and 3700 BC, as measured by de Jong, Mook, and Becker, differ in rise time from those found for the current millennium.

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A statistical analysis of the relationship between Pc4 and Pc5 ULF waves, solar winds and geomagnetic storms for predicting earthquake precursor signatures in low latitude regions

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/880/1/012010 ◽

2021 ◽

Vol 880 (1) ◽

pp. 012010

Author(s):

S N A Syed Zafar ◽

Roslan Umar ◽

N H Sabri ◽

M H Jusoh ◽

A Yoshikawa ◽

...

Keyword(s):

Solar Wind ◽

Geomagnetic Field ◽

Geomagnetic Storms ◽

Earthquake Precursor ◽

Ulf Waves ◽

Low Latitude ◽

Geomagnetic Indices ◽

Solar Winds ◽

Solar Wind Parameters ◽

The Relationship

Abstract Short-term earthquake forecasting is impossible due to the seismometer’s limited sensitivity in detecting the generation of micro-fractures prior to an earthquake. Therefore, there is a strong desire for a non-seismological approach, and one of the most established methods is geomagnetic disturbance observation. Previous research shows that disturbances in the ground geomagnetic field serves as a potential precursor for earthquake studies. It was discovered that electromagnetic waves (EM) in the Ultra-Low Frequency (ULF) range are a promising tool for studying the seismomagnetic effect of earthquake precursors. This study used a multiple regression approach to analyse the preliminary study on the relationship between Pc4 (6.7-22 mHz) and Pc5 (1.7-6.7 mHz) ULF magnetic pulsations, solar wind parameters and geomagnetic indices for predicting earthquake precursor signatures in low latitude regions. The ground geomagnetic field was collected from Davao station (7.00° N, 125.40° E), in the Philippines, which experiences nearby earthquake events (Magnitude <5.0, depth <100 km and epicentre distance from magnetometer station <100 km). The Pc5 ULF waves show the highest variance with four solar wind parameters, namely SWS, SWP, IMF-Bz, SIE and geomagnetic indices (SYM/H) prior to an earthquake event based on the regression model value of R2 = 0.1510. Furthermore, the IMF-Bz, SWS, SWP, SWE, and SYM/H were found to be significantly correlated with Pc5 ULF geomagnetic pulsation. This Pc5 ULF magnetic pulsation behaviour in solar winds and geomagnetic storms establishes the possibility of using Pc5 to predict earthquakes.

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