Spectral Features of Forbush Decreases during Geomagnetic Storms

Baral, Rabin; Adhikari, Binod; Calabia, Andrés; Shah, Munawar; Mishra, Roshan Kumar; Silwal, Ashok; Bohara, Sudarshan; Manandhar, Roshna; Peral, L. del; Frías, M. D. Rodríguez

doi:10.1016/j.jastp.2022.105981

Cited by 12 publications

(3 citation statements)

References 36 publications

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“…Such information has been accessible for the geomagnetic indices since 1868. From oriental naked eye sunspot records and auroral observations, attempts have been made to reconstruct the epochs and even amplitudes of solar maxima over the past two millennia [22,23,24]. However, these reconstructions currently have too many uncertainties to be used as the basis for predictions.…”

Section: Methodsmentioning

confidence: 99%

Solar Activity and Cosmic Ray Intensity Variation with Geomagnetic Activity during 1996–2022

Pal,

Kumar,

Rani

et al. 2024

Ukr. J. Phys.

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The average features of diurnal variation have been observed to change with different phases of the solar cycle, with the variance being substantially bigger at higher energies. The events were classified on the basis of different phases of solar cycles, i.e., the minimum solar activity time period, the maximum solar activity time period, and the declining phase of solar cycle. This research looks at the observed results and the influence of solar variability on cosmic rays and the geomagnetic field from 1996 to 2022. The occasional group includes a Forbush effect decline, transitory decrease, and a ground level enhancement (GLE). The 11-year fluctuation in Galactic Cosmic Rays is also known as the long-term variation, whereas the Forbush effect reduction is known as short-term variation. We investigated the long-term change in the cosmic ray intensity and its relationship to the number of Sun spots (Rz), solar wind speed (

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Section: Methodsmentioning

confidence: 99%

Solar Activity and Cosmic Ray Intensity Variation with Geomagnetic Activity during 1996–2022

Pal,

Kumar,

Rani

et al. 2024

Ukr. J. Phys.

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“…Potential Earthquake Proxies from Remote Sensing Data DOI: http://dx.doi.org/10.5772/intechopen.1005382 [22], the disturbance storm time index (Dst) [23], and the solar flux [24] should be considered to flag the affected observables.…”

Section: Methodologiesmentioning

confidence: 99%

Potential Earthquake Proxies from Remote Sensing Data

Boudriki Semlali,

Molina,

Carvajal Librado

et al. 2024

Sustainable Development

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At present, there is no clear scientific evidence of reliable earthquake precursors that can be used as an early warning system. However, many studies have also reported the existence of faint signatures that appear to be coupled to the occurrence of earthquakes. These anomalies have traditionally been detected using data from in-situ sensors near high-seismicity regions. On the other hand, remote sensors offer the potential of large spatial coverage and frequent revisit time, allowing the observation of remote areas such as deserts, mountains, polar caps, or the ocean. This chapter revises the state-of-the-art of the understanding of lithosphere–atmosphere–ionosphere coupling. It also presents recent studies by the authors’ ongoing investigation on short-to-midterm earthquake precursors. The Earth observation variables discussed are (1) surface temperature anomalies from thermal infrared or microwave radiometer measurements, (2) atmospheric signatures, (3) ionospheric total electron density fluctuations or scintillation measured from GNSS signals, and (4) other geophysical variables, including geomagnetic field fluctuations, changes in the Schumann resonance frequency, or low-frequency electromagnetic radiation. However, despite the seismic hazard risk models that exist and the results shown by these studies, it is still very difficult to predict the occurrence of earthquakes.

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“…[23] continued his accurate research using neutron monitors to study the temporal intensity variations in a part of the lower-energy primary particles spectrum. Finally, he showed that the source of these variations was not related to geomagnetic field variations [19] but to the interplanetary medium [25,26] and, specifically, to solar activity phenomena [27,28]. Moreover, he singled out the sharp, non-periodic CRI decreases in magnitude greater than 6%, which would later be defined as FDs.…”

Section: Introductionmentioning

confidence: 99%

Precursory Signs of Large Forbush Decreases in Relation to Cosmic Rays Equatorial Anisotropy Variation

Papailiou,

Abunina,

Mavromichalaki

et al. 2024

Atmosphere

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Forbush decreases are usually characterized by increased values of cosmic ray anisotropy. The precursory signs, i.e., pre-increases and especially pre-decreases of the cosmic ray intensity, are highly anisotropic phenomena that ordinarily forewarn of such events. Two Cosmic Ray Groups from the National and Kapodistrian University of Athens (NKUA) and the Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radiowave Propagation of the Russian Academy of Sciences (IZMIRAN) have been investigating the existence of precursory signs preceding Forbush decreases in relation to different solar phenomena, interplanetary parameters, and geomagnetic conditions. In this study, large Forbush decreases (magnitude > 5%) accompanied by geomagnetic storms (i.e., geomagnetic index Dst < −100 nT and 5 ≤ Kp-index ≤ 9) and characterized by an equatorial anisotropy 1 h before the onset of the event (Axyb, %) less than 0.8% were examined regarding precursors. In total, 50 events with the aforementioned features were selected and analyzed from the IZMIRAN’s Forbush Effects and Interplanetary Disturbances database concerning the time period from 1969 until 2023. The Ring of Stations method, which depicts the cosmic ray variations for various asymptotic longitudes in relation to time, was applied on each event. The results revealed that clear signs of pre-decreases were not present for the majority of the events. Since particularly strong events were considered, most of them still showed some precursory signs, albeit mainly weak. Despite this, the value of Axyb = 0.8% proves to be a good threshold for the manual selection of FDs with well-expressed precursors.

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Spectral Features of Forbush Decreases during Geomagnetic Storms

Cited by 12 publications

References 36 publications

Solar Activity and Cosmic Ray Intensity Variation with Geomagnetic Activity during 1996–2022

Solar Activity and Cosmic Ray Intensity Variation with Geomagnetic Activity during 1996–2022

Potential Earthquake Proxies from Remote Sensing Data

Precursory Signs of Large Forbush Decreases in Relation to Cosmic Rays Equatorial Anisotropy Variation

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