Amplitude of the Observational Forbush Decreases in the Presence of Cosmic Ray Diurnal Anisotropy During High Solar Activity in 1972

Solar Physics ◽  
2021 ◽  
Vol 296 (7) ◽  
Author(s):  
O. Okike ◽  
J. A. Alhassan
Keyword(s):  
Solar Activity ◽  
Cosmic Ray ◽  
High Solar Activity ◽  
Forbush Decreases ◽  
Diurnal Anisotropy

scholarly journals Cosmic-ray propagation around the Sun: investigating the influence of the solar magnetic field on the cosmic-ray Sun shadow

2020 ◽  
Vol 633 ◽  
pp. A83
Author(s):  
J. Becker Tjus ◽  
P. Desiati ◽  
N. Döpper ◽  
H. Fichtner ◽  
J. Kleimann ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Activity ◽  
Solar Cycle ◽  
Cosmic Rays ◽  
Solar Magnetic Field ◽  
Cosmic Ray ◽  
High Energy ◽  
High Solar Activity ◽  
The Sun ◽  
Theoretical Understanding

The cosmic-ray Sun shadow, which is caused by high-energy charged cosmic rays being blocked and deflected by the Sun and its magnetic field, has been observed by various experiments, such as Argo-YBJ, Tibet, HAWC, and IceCube. Most notably, the shadow’s size and depth was recently shown to correlate with the 11-year solar cycle. The interpretation of such measurements, which help to bridge the gap between solar physics and high-energy particle astrophysics, requires a solid theoretical understanding of cosmic-ray propagation in the coronal magnetic field. It is the aim of this paper to establish theoretical predictions for the cosmic-ray Sun shadow in order to identify observables that can be used to study this link in more detail. To determine the cosmic-ray Sun shadow, we numerically compute trajectories of charged cosmic rays in the energy range of 5−316 TeV for five different mass numbers. We present and analyze the resulting shadow images for protons and iron, as well as for typically measured cosmic-ray compositions. We confirm the observationally established correlation between the magnitude of the shadowing effect and both the mean sunspot number and the polarity of the magnetic field during the solar cycle. We also show that during low solar activity, the Sun’s shadow behaves similarly to that of a dipole, for which we find a non-monotonous dependence on energy. In particular, the shadow can become significantly more pronounced than the geometrical disk expected for a totally unmagnetized Sun. For times of high solar activity, we instead predict the shadow to depend monotonously on energy and to be generally weaker than the geometrical shadow for all tested energies. These effects should become visible in energy-resolved measurements of the Sun shadow, and may in the future become an independent measure for the level of disorder in the solar magnetic field.

Forbush decreases at different periods of the solar cycle

1968 ◽  
Vol 46 (10) ◽  
pp. S859-S861
Author(s):  
K. Imazhanova ◽  
E. V. Kolomeets ◽  
M. Musabaev ◽  
V. T. Pivneva
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Cosmic Ray ◽  
Particle Energy ◽  
Forbush Decreases ◽  
Cosmic Ray Intensity ◽  
Recovery Times ◽  
Using Data ◽  
Neutron Component ◽  
Worldwide Network

An analysis of Forbush decreases occurring at different periods of the solar cycle has been carried out using data from the worldwide network of stations registering the neutron component of the cosmic-ray intensity. The changes of energy spectrum of Forbush decreases have been investigated for the interval from 1957 to 1965, and also the dependence of the decrease and recovery times on particle energy and solar activity.

Comparison and Time Evolution of the Geomagnetic Cutoff at the ISS Position: Internal vs External Earth’s Magnetic Field Models

2017 ◽  
Vol 13 (S335) ◽  
pp. 105-108
Author(s):  
Matteo J. Boschini ◽  
Stefano Della Torre ◽  
Massimo Gervasi ◽  
Davide Grandi ◽  
Giuseppe La Vacca ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Activity ◽  
Large Fraction ◽  
Cosmic Ray ◽  
High Solar Activity ◽  
Earth’S Magnetic Field ◽  
Magnetic Field Data ◽  
Geomagnetic Cutoff ◽  
Earth's Magnetic Field ◽  
Ray Trajectories

AbstractOur back-tracing code (GeoMagSphere) reconstructs the cosmic ray trajectories inside the Earth’s magnetosphere. GeoMagSphere gets the incoming directions of particles entering the magnetopause and disentangles primary from secondary particles (produced in atmosphere) or even particles trapped inside the Earth’s magnetic field. The separation of these particle families allows us to evaluate the geomagnetic rigidity cutoff. The model can be used considering the internal symmetric (IGRF-12) magnetic field only, or adding the asymmetric external one (Tsyganenko models: T89, T96 or TS05). A quantitative comparison among these models is presented for quiet (solar pressure Pdyn < 4 nPa) and disturbed (Pdyn > 4 nPa) periods of solar activity, as well as during solar events like flares, CMEs. In this analysis we focused our attention on magnetic field data in magnetosphere, from Cluster, and simulated cosmic rays for a generic detector on the ISS as for example AMS-02. We found that high solar activity periods, like a large fraction of the period covering years 2011-2015, are better described using IGRF+TS05 model. Results, i.e. the average vertical rigidity cutoff at the ISS orbit, are shown in geographic maps of 2° × 2° cells.

Testing the Impact of Coronal Mass Ejections on Cosmic Ray Intensity Modulation with Algorithm selected Forbush Decreases

2020 ◽  
Author(s):  
O Okike ◽  
O C Nwuzor ◽  
F C Odo ◽  
E U Iyida ◽  
J E Ekpe ◽  
...  
Keyword(s):  
Coronal Mass Ejections ◽  
Cosmic Ray ◽  
Forbush Decreases ◽  
Cosmic Ray Intensity ◽  
Event Identification ◽  
Diurnal Anisotropy ◽  
Current Article ◽  
Galactic Cosmic Ray ◽  
The Impact ◽  
The Relationship

Abstract The relationship between coronal mass ejections (CMEs) and Forbush decreases (FDs) has been investigated in the past. But selection of both solar events are difficult. Researchers have developed manual and automated methods in efforts to identify CMEs as well as FDs. While scientists investigating CMEs have made significant advancement, leading to several CME catalogues, including manual and automated events catalogues, those analyzing FDs have recorded relatively less progress. Till date, there are no comprehensive manual FD catalogues, for example. There are also paucity of Automated FD lists. Many investigators, therefore, attempt to manually select FDs which are subsequently used in the analysis of the impact of CMEs on galactic cosmic ray (GCR) flux depressions. However, some of the CME versus FD correlation results might be biased since manual event identification is usually subjective, unable to account for the presence of solar-diurnal anisotropy which characterizes GCR flux variations. The current article investigates the relation between CMEs and FDs with emphasis on accurate and careful Forbush event selection.

Short-term variation of cosmic ray diurnal anisotropy and solar activity

2008 ◽  
Vol 46 (1) ◽  
pp. 94-96 ◽  
Author(s):  
R. K. Mishra ◽  
R. A. Mishra
Keyword(s):  
Solar Activity ◽  
Cosmic Ray ◽  
Short Term ◽  
Diurnal Anisotropy ◽  
Term Variation

HIGH-ALTITUDE COSMIC RAY MEASUREMENTS AT FORT CHURCHILL

1960 ◽  
Vol 38 (5) ◽  
pp. 638-641 ◽  
Author(s):  
I. B. McDiarmid ◽  
D. C. Rose
Keyword(s):  
Solar Activity ◽  
High Altitude ◽  
Solar Minimum ◽  
Solar Maximum ◽  
Cosmic Ray ◽  
Geiger Counter ◽  
Low Energy ◽  
High Solar Activity ◽  
Energy Radiation ◽  
Cosmic Ray Intensity

Measurements with rocket-borne Geiger counters have been carried out at altitudes up to 250 km at Fort Churchill, Manitoba. The total primary cosmic ray intensity at a time near a solar maximum has been determined and compared with other measurements taken at times of high solar activity and also with other Geiger counter measurements obtained near a solar minimum. A low-energy radiation was observed whose intensity increased with altitude up to about 25% of the primary intensity at 250 km.

NEW NEUTRON MONITOR STATION IN BAKSAN VALLEY

2005 ◽  
Vol 20 (29) ◽  
pp. 6696-6698 ◽  
Author(s):  
S. N. KARPOV ◽  
Z. M. KARPOVA ◽  
V. B. PETKOV ◽  
E. V. VASHENYUK ◽  
V. G. YANKE
Keyword(s):  
Solar Activity ◽  
High Altitude ◽  
Neutron Monitor ◽  
World Wide ◽  
Cosmic Ray ◽  
Northern Caucasus ◽  
Forbush Decreases ◽  
Monitor Station ◽  
The World

In autumn 2003 a new high-altitude neutron monitor (NM) station located in the Baksan Valley of Northern Caucasus was included in the world-wide network of NMs. The Baksan NM has already registered powerful cosmic ray variations (Forbush–decreases) connected with solar activity in October–November 2003. Since February 2004 the Baksan NM data are accessible via Internet: 〈〉

THE VARIATION OF SEA LEVEL COSMIC RAY INTENSITY BETWEEN 1954 AND 1957

1958 ◽  
Vol 36 (7) ◽  
pp. 824-839 ◽  
Author(s):  
A. G. Fenton ◽  
D. C. Rose ◽  
K. B. Fenton
Keyword(s):  
Solar Activity ◽  
Sea Level ◽  
Geomagnetic Latitude ◽  
Cosmic Ray ◽  
High Solar Activity ◽  
General Level ◽  
Intensity Level ◽  
Cosmic Ray Intensity ◽  
Primary Cosmic Radiation ◽  
The One

Results from neutron monitors and meson telescopes at Ottawa (geomagnetic latitude 57° N.) and Resolute (geomagnetic latitude 83° N.) are presented for the years 1954–57, a period of increasing solar activity. The results indicate that the sea level meson intensity at these latitudes decreased by 5–6% between April 1954 and December 1957. During the same period the intensity of the nucleonic component at these stations decreased by over 22%. Investigation of the relative response of the two types of recorder to transient decreases during this period indicates that the long term change in the intensity level cannot be explained completely as an accumulation of shorter transient decreases, which become more frequent at times of high solar activity. It is concluded that the transient decreases are superimposed upon the longer term changes, each being produced by a separate modulation process but ultimately controlled by the general level of solar activity. Significant differences are found in the shape of transient decreases observed at the Canadian stations, both between different components at the one station and the same component at different stations. These may be interpreted as due to a varying energy dependence from one transient decrease to another, and to anisotropy in the primary cosmic radiation at these times.

The cosmic-ray intensity variations with periods of 19-24 days

1968 ◽  
Vol 46 (10) ◽  
pp. S831-S834
Author(s):  
G. A. Bazilevskaya
Keyword(s):  
Solar Activity ◽  
Sunspot Number ◽  
Neutron Monitor ◽  
Cosmic Ray ◽  
High Solar Activity ◽  
Radio Emissions ◽  
Cosmic Ray Intensity ◽  
Cyclic Variations

Sporadic cyclic variations of the cosmic-ray intensity with periods of 19 to 24 days have been found from the results of balloon and neutron monitor observations. These variations were observed mainly in the years of high solar activity, 1958–62. They appeared to be caused by the general solar activity which, as our treatment has shown, undergoes similar cyclic variations (according to sunspot number or 10.7-cm radio-emissions). The variations under investigation appear with a lag of about 1.5 months compared with the solar-activity variations.

Sign in / Sign up

Export Citation Format

Share Document