scholarly journals Amplitude of the Usual Cosmic Ray Diurnal and Enhanced Anisotropies: Implications for the Observed Magnitude, Timing, and Ranking of Forbush Decreases

2021 ◽  
Vol 915 (1) ◽  
pp. 60
Author(s):  
O. Okike
Keyword(s):  
Cosmic Ray ◽  
Forbush Decreases

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 Effects of cosmic ray decreases on cloud microphysics

2012 ◽  
Vol 12 (2) ◽  
pp. 3595-3617 ◽  
Author(s):  
J. Svensmark ◽  
M. B. Enghoff ◽  
H. Svensmark
Keyword(s):  
Cloud Condensation Nuclei ◽  
Cosmic Ray ◽  
Liquid Water Content ◽  
Total Solar Irradiance ◽  
Cloud Microphysics ◽  
Forbush Decreases ◽  
Cloud Data ◽  
Sigma Level ◽  
Cloud Properties ◽  
Simple Equations

Abstract. Using cloud data from MODIS we investigate the response of cloud microphysics to sudden decreases in galactic cosmic radiation – Forbush decreases – and find responses in effective emissivity, cloud fraction, liquid water content, and optical thickness above the 2–3 sigma level 6–9 days after the minimum in atmospheric ionization and less significant responses for effective radius and cloud condensation nuclei (<2 sigma). The magnitude of the signals agree with derived values, based on simple equations for atmospheric parameters. Furthermore principal components analysis gives a total significance of the signal of 3.1 sigma. We also see a correlation between total solar irradiance and strong Forbush decreases but a clear mechanism connecting this to cloud properties is lacking. There is no signal in the UV radiation. The responses of the parameters correlate linearly with the reduction in the cosmic ray ionization. These results support the suggestion that ions play a significant role in the life-cycle of clouds.

Unusual Cosmic Ray Variations During the Forbush Decreases of June 2015

Solar Physics ◽  
2018 ◽  
Vol 293 (4) ◽  
Author(s):  
E. Samara ◽  
A. Smponias ◽  
I. Lytrosyngounis ◽  
D. Lingri ◽  
H. Mavromichalaki ◽  
...  
Keyword(s):  
Cosmic Ray ◽  
Forbush Decreases

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

Solar wind temperature–velocity relationship over the last five solar cycles and Forbush decreases associated with different types of interplanetary disturbance

2020 ◽  
Vol 500 (3) ◽  
pp. 2786-2797
Author(s):  
A A Melkumyan ◽  
A V Belov ◽  
M A Abunina ◽  
A A Abunin ◽  
E A Eroshenko ◽  
...  
Keyword(s):  
Solar Wind ◽  
High Speed ◽  
Coronal Holes ◽  
Cosmic Ray ◽  
Magnetic Clouds ◽  
Solar Cycles ◽  
Forbush Decreases ◽  
Proton Temperature ◽  
Interaction Regions ◽  
Interplanetary Disturbance

ABSTRACT The behaviour of the solar wind (SW) proton temperature and velocity and their relationship during Forbush decreases (FDs) associated with various types of solar source – coronal mass ejections (CMEs) and coronal holes (CHs) – have been studied. Analysis of cosmic ray variations, SW temperature, velocity, density, plasma beta, and magnetic field (from 1965–2019) is carried out using three databases: the OMNI database, Variations of Cosmic Rays database (IZMIRAN) and Forbush Effects & Interplanetary Disturbances database (IZMIRAN). Comparison of the observed SW temperature (T) and velocity (V) for the undisturbed SW allows us to derive a formula for the expected SW temperature (Texp, the temperature given by a T–V formula, if V is the observed SW speed). The results reveal a power-law T–V dependence with a steeper slope for low speeds (V &lt; 425 km s−1, exponent = 3.29 ± 0.02) and flatter slope for high speeds (V &gt; 425 km s−1, exponent = 2.25 ± 0.02). A study of changes in the T–V dependence over the last five solar cycles finds that this dependence varies with solar activity. The calculated temperature index KT = T/Texp can be used as an indicator of interplanetary and solar sources of FDs. It usually has abnormally large values in interaction regions of different-speed SW streams and abnormally low values inside magnetic clouds (MCs). The results obtained help us to identify the different kinds of interplanetary disturbance: interplanetary CMEs, sheaths, MCs, corotating interaction regions, high-speed streams from CHs, and mixed events.

scholarly journals Hysteresis of Primary Cosmic Rays Associated with Forbush Decreases

1976 ◽  
Vol 29 (2) ◽  
pp. 89
Author(s):  
RS Rajan
Keyword(s):  
Regression Analysis ◽  
Cosmic Rays ◽  
Cosmic Ray ◽  
Differential Modulation ◽  
Forbush Decreases ◽  
Primary Cosmic Rays

Regression analysis of primary cosmic ray intensities during Forbush decreases indicates the existence of a differential modulation between high and low rigidity primaries.

The effect of Forbush decreases on the polar-night HOx concentration

2021 ◽  
Author(s):  
Irina Mironova
Keyword(s):  
Forbush Decrease ◽  
Cosmic Ray ◽  
Solar Proton ◽  
Polar Night ◽  
Forbush Decreases ◽  
Ozone Loss ◽  
Solar Proton Events ◽  
Hydrogen Oxide ◽  
The Impact ◽  
Ionization Rates

&lt;div&gt; &lt;div&gt; &lt;div&gt; &lt;p&gt;It is well-known that energetic particle precipitations during solar proton events increase ionization rates in the middle atmosphere enhancing the production of hydrogen oxide radicals (HOx) involved in the catalytic ozone destruction cycle. There are many studies where the contribution of energetic particles to the formation of hydrogen oxide radicals and ozone loss has been widely investigated. However, until now, there was no solid evidence that the reduction in galactic cosmic ray fluxes during a magnetic storm, known as Forbush-effect, directly and noticeably affects the polar-night stratospheric chemistry.&lt;br&gt;Here, the impact of the Forbush decrease on the behaviour of hydrogen oxide radicals was explored using the chemistry-climate model SOCOL.&lt;br&gt;We found that hydrogen oxide radical lost about half of its concentration over the polar boreal night stratosphere owing to a reduction in ionization rates caused by Forbush decreases after solar proton events occurred on 17 and 20 of January 2005. A robust response in ozone was not found. There is not any statistically significant response in (NOx) on Forbush decrease events as well as over summertime in the southern polar region.&lt;br&gt;The results of this study can be used to increase the veracity of ozone loss estimation if stronger Forbush events can have a place.&lt;/p&gt; &lt;p&gt;Reference: Mironova I, Karagodin-Doyennel A and Rozanov E (2021) , The effect of Forbush decreases on the polar-night HOx concentration affecting stratospheric ozone. Front. Earth Sci. 8:618583. doi: 10.3389/feart.2020.618583&lt;/p&gt; &lt;p&gt;https://www.frontiersin.org/articles/10.3389/feart.2020.618583/full&lt;/p&gt; &lt;p&gt;The study was supported by the Russian Science Foundation grant (RSF project No. 20-67-46016).&lt;/p&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt;

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