Characteristics of quiet as well as enhanced diurnal anisotropy of cosmic radiation

Rao, U. R.; Ananth, A. G.; Agrawal, S. P.

doi:10.1016/0032-0633(72)90114-6

Cited by 47 publications

(23 citation statements)

References 24 publications

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“…Special type of consecutive days having abnormally high or low amplitudes in daily variation of cosmic rays have been reported several times earlier with explanation of sources and sinks in anti-garden-hose and garden-hose directions (Jadhav et al, 1983;Rao et al, 1972;Tiwari, 1994). The existence of high and low amplitude anisotropic wave trains have been revealed through the long-term study of cosmic ray intensity.…”

Section: Introductionmentioning

confidence: 81%

“…Several workers have attempted to find the possible origin of the 'large amplitude wave trains' of cosmic ray neutron intensity to develop a suitable realistic theoretical model, which can explain the diurnal anisotropy in individual days. Hashim and Thambyahpillai (1969) and Rao et al (1972) have shown that the enhanced diurnal variation of large amplitude events exhibits a maximum intensity in space around the anti-garden-hose direction (2100 Hr) and a minimum intensity in space around the garden-hose direction (0900 Hr). Kane (1970) and Bussoletti (1973) have noticed that quite often an enhanced intensity is presented along the corotational direction and it is not correlated with the garden-hose direction.…”

Section: Introductionmentioning

confidence: 99%

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Modulation of cosmic rays at different cutoff rigidity

Agarwal

Mishra

2008

Braz. J. Phys.

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The present work deals with the study of first three harmonics of cosmic ray intensity on geo-magnetically quiet days over the period [1981][1982][1983][1984][1985][1986][1987][1988][1989][1990][1991][1992][1993] for Deep River and Inuvik neutron monitoring stations having mid and low cutoff rigidity. The amplitude of first harmonic remains high for Deep River having mid cutoff rigidity as compared to Inuvik neutron monitor having low cutoff rigidity on quiet days. The diurnal amplitude significantly decreases and phase shifts towards an earlier time during solar activity minimum years at both Deep River and Inuvik. The amplitude of second harmonic significantly enhanced during solar activity minimum as well as maximum at Deep River and remains low during solar activity maximum at Inuvik, whereas the phase shifts towards an earlier time during solar maximum for both the stations. The amplitude of the third harmonic significantly enhanced during solar activity minimum at Deep River and on solar activity minimum at Inuvik, whereas the phase does not show any significant characteristics and fluctuates quite frequently. The amplitude of semi/tri-diurnal anisotropy has a good positive correlation, while the others (i.e. amplitude and phase) have very weak correlation with solar wind velocity on quiet days at Deep River station during 1981-1993. The solar wind velocity significantly remains in the range 350 to 425 km/s i.e. being nearly average on quiet days. The amplitude and direction of the anisotropy on quiet days are weakly dependent on high-speed solar wind streams for two neutron monitoring station of mid and low cutoff rigidity threshold. The amplitude as well as direction of second harmonic has a good anti-correlation with IMF Bz and the product V x Bz on quiet days at Deep River station. However, the direction of second and third harmonic has a good anti-correlation with IMF Bz and the product V x Bz on quiet days at Inuvik station.

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Section: Introductionmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Modulation of cosmic rays at different cutoff rigidity

Agarwal

Mishra

2008

Braz. J. Phys.

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“…As mentioned in section 1, both GCRs and SCRs have meteorological importance mainly because of their ionizing power (Sarabhai, 1942;Rao et al, 1972;Bazilevskaya, 2000;Rao, 2011;Mironova et al, 2015). GCRs cause ionization mainly in the lowest part of the atmosphere while SCRs cause ionization mainly at tropopuase and stratosphere altitudes (Calisto et al, 2011).…”

Section: Cosmic Ray Fluxmentioning

confidence: 99%

“…The studies to understand the effects of solar activity and cosmic rays on climate and weather have a long history (Wilson, 1920;Sarabhai, 1942;Rao et al, 1972;Harrison and Aplin, 2001;Rycroft et al, 2012). The total solar irradiance provides first order (variable) energy input to the lower atmosphere.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Influence of Galactic Cosmic Rays on Clouds and Climate in Antarctica

2017

Proceedings of the Indian National Science Academy

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“…The average diurnal anisotropy vector has been explained as a consequence of the equilibrium established between the radial convection of the cosmic ray particles by solar wind and the inward diffusion of particles along the interplanetary magnetic fields due to the radial gradient [14,15,16]; the anisotropy is simply visualized as corotation of particles with the solar system magnetic fields [17,18]. Further, a detailed analysis of diurnal anisotropy vectors on a long-term basis [19,20,21] and on a day-to-day basis [22] clearly indicates that a corotation theory derived by the convection-diffusion model is insufficient to understand the diurnal anisotropy characteristics and the systematic shifting of the average diurnal anisotropy to earlier hours envisages the need of an additional mechanism for explaining the long-term behaviour of diurnal anisotropy.…”

Section: Introductionmentioning

confidence: 99%

Cosmic ray anisotropy and solar activity

Mishra¹,

Mishra²

2007

Braz. J. Phys.

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In this paper an attempt is made to study the occurrence of a large number of high amplitude anisotropic wave train events in cosmic ray intensity during 1981-1994 and to identify a possible correlation with solar activity using the hourly neutron monitor data of Deep River station. The diurnal time of maximum for both HAE as well as for all days is found to significantly shift towards an earlier time as compared to the corotational/azimuthal direction since the year 1991 onward. It is found that diurnal amplitude and 10.7-cm solar radio flux significantly deviates and reaches to its maximum and phase remains in the corotational direction during the years close to solar activity maximum for HAE. The occurrence of high amplitude anisotropic wave train events is dominant during solar activity minimum as well as maximum years. The amplitude as well as phase of the cosmic ray diurnal anisotropy during HAEs is well correlated with solar activity. The amplitude as well as phase of diurnal anisotropy shows very nominal correlation with 10.7-cm solar radio flux (r = 0.48, 0.47). However, the frequency of occurrence of HAEs shows a very weak correlation (r = -0.36) with 10.7-cm solar radio flux.

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Characteristics of quiet as well as enhanced diurnal anisotropy of cosmic radiation

Cited by 47 publications

References 24 publications

Modulation of cosmic rays at different cutoff rigidity

Modulation of cosmic rays at different cutoff rigidity

Investigation of the Influence of Galactic Cosmic Rays on Clouds and Climate in Antarctica

Cosmic ray anisotropy and solar activity

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