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.

Force-field parameterization of the galactic cosmic ray spectrum: Validation for Forbush decreases

2015 ◽  
Vol 55 (12) ◽  
pp. 2940-2945 ◽  
Author(s):  
I.G. Usoskin ◽  
G.A. Kovaltsov ◽  
O. Adriani ◽  
G.C. Barbarino ◽  
G.A. Bazilevskaya ◽  
...  
Keyword(s):  
Force Field ◽  
Cosmic Ray ◽  
Forbush Decreases ◽  
Force Field Parameterization ◽  
Galactic Cosmic Ray

scholarly journals Cosmic rays linked to rapid mid-latitude cloud changes

2010 ◽  
Vol 10 (22) ◽  
pp. 10941-10948 ◽  
Author(s):  
B. A. Laken ◽  
D. R. Kniveton ◽  
M. R. Frogley
Keyword(s):  
Causal Relationship ◽  
General Circulation ◽  
Cloud Cover ◽  
Circulation Model ◽  
Cosmic Ray ◽  
Reanalysis Data ◽  
Short Term ◽  
Earth’S Climate ◽  
Relationship Of ◽  
Galactic Cosmic Ray

Abstract. The effect of the Galactic Cosmic Ray (GCR) flux on Earth's climate is highly uncertain. Using a novel sampling approach based around observing periods of significant cloud changes, a statistically robust relationship is identified between short-term GCR flux changes and the most rapid mid-latitude (60°–30° N/S) cloud decreases operating over daily timescales; this signal is verified in surface level air temperature (SLAT) reanalysis data. A General Circulation Model (GCM) experiment is used to test the causal relationship of the observed cloud changes to the detected SLAT anomalies. Results indicate that the anomalous cloud changes were responsible for producing the observed SLAT changes, implying that if there is a causal relationship between significant decreases in the rate of GCR flux (~0.79 GU, where GU denotes a change of 1% of the 11-year solar cycle amplitude in four days) and decreases in cloud cover (~1.9 CU, where CU denotes a change of 1% cloud cover in four days), an increase in SLAT (~0.05 KU, where KU denotes a temperature change of 1 K in four days) can be expected. The influence of GCRs is clearly distinguishable from changes in solar irradiance and the interplanetary magnetic field. However, the results of the GCM experiment are found to be somewhat limited by the ability of the model to successfully reproduce observed cloud cover. These results provide perhaps the most compelling evidence presented thus far of a GCR-climate relationship. From this analysis we conclude that a GCR-climate relationship is governed by both short-term GCR changes and internal atmospheric precursor conditions.

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.

scholarly journals Possible effects on Earth's climate due to reduced atmospheric ionization by GCR during Forbush Decreases

2016 ◽  
Vol 12 (S328) ◽  
pp. 298-300
Author(s):  
Williamary Portugal ◽  
Ezequiel Echer ◽  
Mariza Pereira de Souza Echer ◽  
Alessandra Abe Pacini
Keyword(s):  
Surface Temperature ◽  
Chemical Properties ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Forbush Decreases ◽  
First Results ◽  
Earth’S Climate ◽  
Galactic Cosmic Ray ◽  
Cosmic Ray Flux ◽  
Atmospheric Ionization

AbstractThis work presents the first results of a study about possible effects on the surface temperature during short periods of lower fluxes of Galactic Cosmic Rays at Earth, called Forbush Decreases. There is a hypothesis that the Galactic Cosmic Ray flux decreases cause changes on the physical-chemical properties of the atmosphere. We have conducted a study to investigate these possible effects on several latitudinal regions, around the ten strongest FDs occurred from 1987 to 2015. We have found a possible increase on the surface temperature at middle and high latitudes during the occurence of these events.

Long- and Short-term Variability of Galactic Cosmic-Ray Radial Intensity Gradients between 1 and 9.5 au: Observations by Cassini, BESS, BESS-Polar, PAMELA, and AMS-02

2020 ◽  
Vol 904 (2) ◽  
pp. 165
Author(s):  
Elias Roussos ◽  
Konstantinos Dialynas ◽  
Norbert Krupp ◽  
Peter Kollmann ◽  
Christopher Paranicas ◽  
...  
Keyword(s):  
Cosmic Ray ◽  
Short Term ◽  
Galactic Cosmic Ray ◽  
Short Term Variability

Utilizing galactic cosmic rays as signatures of coronal mass ejections

2021 ◽  
Author(s):  
Mateja Dumbovic
Keyword(s):  
Coronal Mass Ejections ◽  
Interplanetary Space ◽  
Flux Rope ◽  
Forbush Decrease ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Forbush Decreases ◽  
Magnetic Structures ◽  
Different Types ◽  
Galactic Cosmic Ray

<p>Coronal mass ejections (CMEs) are the most violent eruptions in the solar system. They are one of the main drivers of the heliospheric variability and cause various interplanetary as well as planetary disturbances. One of their very common in-situ signatures are short-term reductions in the galactic cosmic ray (GCR) flux (i.e. Forbush decreases), which are measured by ground-based instruments at Earth and Mars, as well as various spacecraft throughout the heliosphere (most recently by Solar Orbiter). In general, interplanetary magnetic structures interact with GCRs producing depressions in the GCR flux. Therefore, different types of interplanetary magnetic structures cause different types of GCR depressions, allowing us to distinguish between them. In the interplanetary space the CME typically consists of two structures: the presumably closed flux rope and the shock/sheath which is formed ahead of the flux rope as it propagates and expands in the interplanetary space. Interaction of GCRs with these two structures is modelled separately, where the flux-rope related Forbush decrease can be modelled assuming that the GCRs diffuse slowly into the expanding flux rope, which is initially empty at its center (ForbMod model). The resulting Forbush decrease at a given time, i.e. heliospheric distance, reflects the evolutionary properties of CMEs. However, ForbMod is not yet able to take into account complex, non-self-similar evolution of the flux rope. Nevertheless, Forbush decreases can undoubtedly give us information on the CMEs in the heliosphere, especially where other measurements are lacking, and with further development, Forbush decrease reverse modelling could provide insight into the CME evolution.</p>

scholarly journals Relationship of the characteristics of large Forbush decreases and the heliolongitude of their sources

2021 ◽  
pp. 125-129
Author(s):  
Maria Papailiou ◽  
Maria Abunina ◽  
Anatoly V. Belov ◽  
Eugenia A. Eroshenko ◽  
Victor G. Yanke ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Flares ◽  
Solar Wind Speed ◽  
Cosmic Ray ◽  
Survey Method ◽  
Forbush Decreases ◽  
Solar Source ◽  
Time Profiles ◽  
Time Period ◽  
Relationship Of

In this investigation the different features and characteristics of Forbush decreases, with emphasis on large For- bush decreases (≥4%) and their association to solar sources, are being examined. According to the heliolongitude of the solar source, the events under study were separated into three subcategories: western (21º ≤ heliolongitude ≤ 60º), eastern (-60º ≤ heliolongitude ≤ -21º) and central (-20º ≤ heliolongitude ≤ 20º). The selected events cover the time period 1967 - 2017. The ‘Global Survey Method’ was used for analyzing the Forbush decreases, along with data on solar flares, solar wind speed, geomagnetic indices (Kp and Dst), and interplanetary magnetic field. In ad - dition, the superimposed epoch method was applied in order to plot the time profiles for the aforementioned group of events. This detailed analysis reveals interesting results concerning the features of cosmic ray decreases in re- gard to the heliolongitude of the solar sources. Moreover, it is also shown that large Forbush decreases, regardless of the heliolongitude of the solar source, are accompanied by increased geomagnetic activity and increased aniso- tropy, including anisotropy before the events, which can serve as a typical precursor of Forbush decreases.

Sign in / Sign up

Export Citation Format

Share Document