Changes in the cosmic-ray power spectrum during solar flares

1991 ◽  
Vol 69 (8-9) ◽  
pp. 976-980
Author(s):  
K. Kudela ◽  
A. G. Ananth ◽  
D. Venkatesan
Keyword(s):  
Power Spectrum ◽  
Solar Flares ◽  
Cosmic Ray ◽  
Ground Level ◽  
Frequency Interval ◽  
Spectral Form ◽  
High Energies ◽  
Power Spectral ◽  
Before And After ◽  
Monitor Data

The power spectrum analyses of cosmic-ray neutron-monitor data at two different cutoff rigidity stations, Calgary (1.09 GV) and Lomnicky Stit (4.0 GV), exhibit similar changes in power spectral form in the frequency interval 10−5–10−3 Hz before and after the six solar flare events that occurred from January 1989 to June 1990. The power spectrum index n at both stations, which showed significantly lower values one day before the flare onset, indicated a sharp steepening of the spectral shape following the flare event. The change in the power spectrum is attributed to the redistribution of inhomogeneities near the sun, produced before the solar flares in which cosmic-ray particles are accelerated to high energies, to produce a ground level event.

The shape of the power spectrum of cosmic ray at ground level up to 7 × 10−3 Hz

1975 ◽  
Vol 23 (12) ◽  
pp. 1603-1609 ◽  
Author(s):  
M.R. Attolini ◽  
S. Cecchini ◽  
I. Guidi ◽  
M. Galli
Keyword(s):  
Power Spectrum ◽  
Cosmic Ray ◽  
Ground Level

scholarly journals All-sky angular power spectrum – I. Estimating brightness temperature fluctuations using the 150-MHz TGSS survey

2020 ◽  
Vol 494 (2) ◽  
pp. 1936-1945 ◽  
Author(s):  
Samir Choudhuri ◽  
Abhik Ghosh ◽  
Nirupam Roy ◽  
Somnath Bharadwaj ◽  
Huib T Intema ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Galactic Plane ◽  
Cosmic Ray ◽  
Point Sources ◽  
Synchrotron Emission ◽  
Angular Power Spectrum ◽  
Latitude Range ◽  
Diffuse Halo ◽  
Sky Survey ◽  
Before And After

ABSTRACT Measurements of the Galactic synchrotron emission are important for the 21-cm studies of the epoch of reionization. The study of synchrotron emission is also useful for quantifying the fluctuations in the magnetic field and the cosmic-ray electron density of the turbulent interstellar medium (ISM) of our Galaxy. Here, we present the all-sky angular power spectrum (Cℓ) measurements of the diffuse synchrotron emission obtained using the TIFR GMRT Sky Survey (TGSS) at 150 MHz. We estimate Cℓ using visibility data both before and after subtracting the modelled point sources. The amplitude of the measured Cℓ decreases significantly after subtracting the point sources, and it is slightly higher in the Galactic plane for the residual data. The residual Cℓ is most likely to be dominated by the Galactic synchrotron emission. The amplitude of the residual Cℓ decreases significantly away from the Galactic plane. We find that the measurements are quite symmetric in the Northern and Southern hemispheres except in the latitude range 15°−30°, which is the transition region from the disc-dominated to the diffuse halo-dominated region. A comparison between this interferometric measurement and the scaled version of the Haslam rms map at 150 MHz shows that the correlation coefficient (r) is greater than 0.5 for most of the latitude ranges considered here. This indicates that the TGSS is quite sensitive to the diffuse Galactic synchrotron radiation.

Improved Approach in the Coupling Function Between Primary and Ground Level Cosmic Ray Particles Based on Neutron Monitor Data

Solar Physics ◽  
2021 ◽  
Vol 296 (6) ◽  
Author(s):  
L. Xaplanteris ◽  
M. Livada ◽  
H. Mavromichalaki ◽  
L. Dorman ◽  
M. K. Georgoulis ◽  
...  
Keyword(s):  
Neutron Monitor ◽  
Cosmic Ray ◽  
Ground Level ◽  
Coupling Function ◽  
Neutron Monitor Data ◽  
Monitor Data

The Cosmic Ray Ground-level Enhancement of 24 October 1989

1994 ◽  
Vol 11 (1) ◽  
pp. 28-32 ◽  
Author(s):  
J. L. Cramp ◽  
J. E. Humble ◽  
M. L. Duldig
Keyword(s):  
Pitch Angle ◽  
Cosmic Ray ◽  
Ground Level ◽  
Model Fit ◽  
South Pole ◽  
Neutron Monitors ◽  
Ground Level Enhancement ◽  
Apparent Source ◽  
Worldwide Network ◽  
Monitor Data

AbstractThe cosmic ray ground-level enhancement (GLE) of 24 October 1989 was the last of a series of GLEs associated with the same solar active region. Intensity enhancements were observed by at least 31 neutron monitors in the worldwide network, with the largest increase (~200%) observed at South Pole, Antarctica around 20:30 UT. Using a least-squares model fit to all available neutron monitor data, spectra, apparent source directions and particle pitch angle distributions have been derived. The effect of disturbed geomagnetic conditions has also been taken into account.

Modeling the solar cosmic ray event of 13 December 2006 using ground level neutron monitor data

2009 ◽  
Vol 43 (4) ◽  
pp. 474-479 ◽  
Author(s):  
C. Plainaki ◽  
H. Mavromichalaki ◽  
A. Belov ◽  
E. Eroshenko ◽  
V. Yanke
Keyword(s):  
Neutron Monitor ◽  
Cosmic Ray ◽  
Ground Level ◽  
Neutron Monitor Data ◽  
Monitor Data

Solar Flare Increase of Cosmic Ray Intensity on November 22, 1977

1978 ◽  
Vol 3 (3) ◽  
pp. 238-241 ◽  
Author(s):  
A. G. Fenton ◽  
K. B. Fenton ◽  
J. E. Humble
Keyword(s):  
Solar Flares ◽  
Average Rate ◽  
Sunspot Cycle ◽  
Cosmic Ray ◽  
Ground Level ◽  
Solar Cycles ◽  
Neutron Monitors ◽  
Cosmic Ray Intensity ◽  
The Past ◽  
The World

Solar flares for which protons of relativistic energies reach Earth are rare events compared with the number in which non-relativistic protons are produced. For instance, Shea and Smart (1978) have listed 139 proton events for the interval 1955-69 of which 17 were GLE’s (i.e. “ground level events” detected by the world network of cosmic ray neutron monitors). We have tentatively identified a further 11 GLE’s in the interval 1970-1977, of which 3 were in 1977 in the sunspot cycle which commenced about mid-1976 (cycle 21). Thus the average rate over the past two solar cycles has been a little over one per year.

CRITERIA FOR THE ASSOCIATION OF SOLAR FLARES WITH GEOMAGNETIC DISTURBANCES

1963 ◽  
Vol 41 (7) ◽  
pp. 1056-1075 ◽  
Author(s):  
R. W. Jenkins ◽  
Irvine Paghis
Keyword(s):  
Solar Flares ◽  
Maximum Concentration ◽  
Cosmic Ray ◽  
Ground Level ◽  
Detailed Examination ◽  
Sudden Commencement ◽  
Strong Positive Correlation ◽  
Geomagnetic Disturbances ◽  
Wide Range ◽  
East West

The statistical relation between solar flares of importance [Formula: see text] and the onset of geomagnetic disturbances was studied for 1949–61. Disturbances were defined as an increase in ap[Formula: see text], occurring within 12 hours or less, and these disturbances include both gradual and sudden commencement events. Associated radio noise bursts at frequencies below 300 Mc were used to select 240 major-burst flares, and the effects of flare importance, time of solar epoch, and associated polar-cap-absorption (PCA) events were considered in turn. A detailed examination was made of the effect of flare heliographic location. There is a strong positive correlation between the occurrence of major-burst flares and geomagnetic disturbances 1 to 3 days afterwards. The degree of correlation is approximately doubled when the major-burst flare is associated with a PCA event. The most probable time delay between flares and disturbances is 1.5 to 2.0 days, and this timing is relatively constant over a wide range of conditions.The dominance of northern storm-flares (Bell 1961) was confirmed for 1949–61. Detailed analysis shows that the effect is strongest for heliographic latitudes above 15 °N. In addition to this effect, there was a consistent western bias of the storm-flares in both the northern and southern hemispheres, for flares associated with either gradual or sudden commencement (SC) events, with maximum concentration occurring at 10 °W. to 15 °W. Major-burst flares associated with PCA events also show this western bias; the data suggest that there is a systematic increase in east–west asymmetry in going from major-burst storm-flares to major-burst PCA flares to PCA flares accompanied by ground-level cosmic-ray increases. The corresponding longitudes of maximum concentration of the associated flares are about 10 °– 15 °W., 45 °W., and 75 °W.

A comparison of catalogues of Forbush decreases identified from individual and a network of neutron monitors: a critical perspective

2021 ◽  
Vol 503 (4) ◽  
pp. 5675-5691
Author(s):  
O Okike ◽  
J A Alhassan ◽  
E U Iyida ◽  
A E Chukwude
Keyword(s):  
Cosmic Ray ◽  
Radiowave Propagation ◽  
Current Work ◽  
Survey Method ◽  
Critical Perspective ◽  
Short Term ◽  
Forbush Decreases ◽  
Academy Of Sciences ◽  
Galactic Cosmic Ray ◽  
Monitor Data

ABSTRACT Short-term rapid depressions in Galactic cosmic ray (GCR) flux, historically referred to as Forbush decreases (FDs), have long been recognized as important events in the observation of cosmic ray (CR) activity. Although theories and empirical results on the causes, characteristics, and varieties of FDs have been well established, detection of FDs, from either isolated detectors' or arrays of neutron monitor data, remains a subject of interest. Efforts to create large catalogues of FDs began in the 1990s and have continued to the present. In an attempt to test some of the proposed CR theories, several analyses have been conducted based on the available lists. Nevertheless, the results obtained depend on the FD catalogues used. This suggests a need for an examination of consistency between FD catalogues. This is the aim of the present study. Some existing lists of FDs, as well as FD catalogues developed in the current work, were compared, with an emphasis on the FD catalogues selected by the global survey method (GSM). The Forbush effects and interplanetary disturbances database (FEID), created by the Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation Russian Academy of Sciences (IZMIRAN), is the only available comprehensive and up to date FD catalogue. While there are significant disparities between the IZMIRAN FD and other event lists, there is a beautiful agreement between FDs identified in the current work and those in the FEID. This may be a pointer to the efficiency of the GSM and the automated approach to FD event detection presented here.

scholarly journals Infrasound of a Wind Turbine Reanalyzed as Power Spectrum and Power Spectral Density

2021 ◽  
pp. 116310
Author(s):  
Johannes Baumgart ◽  
Christoph Fritzsche ◽  
Steffen Marburg
Keyword(s):  
Power Spectrum ◽  
Spectral Density ◽  
Wind Turbine ◽  
Power Spectral Density ◽  
Power Spectral
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