Cosmic Ray Anomalous Enhancement (Not a GLE) During G3 – Strong Geomagnetic Storm on August 26, 2018 Associated with Forbush Effect

Abstract We analyzed the behavior of Cosmic Ray (CR) intensity during geomagnetic events of different nature and strength, using ground-based CR measurements from the World Neutron Monitoring Stations Network. We took account of interplanetary triggers and the geo-effectiveness while choosing the events. Forbush Decrease (FD) was observed when the magnetic fields entangled in and around CME exerts a shielding effect on galactic cosmic radiation, causing a sudden reduction of count rate in the neutron monitors. The results revealed that the FD plunged between -4% and -20% in the chosen events. The FD examined was abnormal and a multi-stage decrement in FD was observed during the event period. The reduction in Cosmic ray intensity was found to be inversely proportional to the cut - off rigidity at the specified neutron monitoring stations. Furthermore, we have also used the Discrete Wavelet Transform (DWT) technique to detect singularity on Forbush decrease at the stations described. The first three decomposition levels have proved sufficient to isolate singularity patterns associated with Forbush decrease in conjunction with events of different nature and intensity, ranging from intense geomagnetic storm to super intense geomagnetic storm to HILDCAA event. Also, we found that the cosmic ray flux was correlated with the IMF-Bz values and the SYM-H index during the process, as indicated by the cross-correlation technique. No noticeable lag has been found between the parameters discussed, which indicates a clear correlation between the IMF Bz and the SYM-H index and the FD.

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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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An investigation into the correlation of geomagnetic storms with tropospheric parameters over the South Pole

Annales Geophysicae ◽

10.5194/angeo-21-1095-2003 ◽

2003 ◽

Vol 21 (5) ◽

pp. 1095-1100 ◽

Cited By ~ 2

Author(s):

M. M. Lam ◽

A. S. Rodger

Keyword(s):

Solar Wind ◽

Geomagnetic Storm ◽

Lower Stratosphere ◽

Geomagnetic Storms ◽

Cosmic Ray ◽

Magnetic Activity ◽

Atmospheric Composition ◽

South Pole ◽

The South ◽

Interplanetary Physics

Abstract. We test the proposal that the Sun’s magnetic activity, communicated via the solar wind, provides a link between solar variability and the Earth’s climate in the Antarctic troposphere. The strength of a geomagnetic storm is one indicator of the state of the solar wind; therefore, we use the dates of 51 moderate to strong winter geomagnetic storms from the period 1961–1990 to conduct a series of superposed epoch analyses of the winter South Pole isobaric height and temperature, at pressures of between 100–500 mbar. Using Student’s t -test to compare the mean value of the pre- and post-storm data sets, we find no evidence to support the hypothesis that there is a statistically-significant correlation between the onset of a geomagnetic storm and changes in the isobaric temperature or height of the troposphere and lower stratosphere over the South Pole during winter months. This concurs with a similar study of the variability of the troposphere and lower stratosphere over the South Pole (Lam and Rodger, 2002) which uses drops in the level of observed galactic cosmic ray intensity, known as Forbush decreases, as a proxy for solar magnetic activity instead of geomagnetic storms.Key words. Interplanetary physics (solar wind plasma; cosmic rays) – Atmospheric composition and structure (pressure, density and temperature)

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