Transient perturbations and their effects in the heliosphere, the geo-magnetosphere, and the Earth’s atmosphere: Space weather perspective |
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Authors: | Badruddin |
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Institution: | (1) Department of Physics, Aligarh Muslim University, 202 002 Aligarh, India |
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Abstract: | We discuss the effects of certain dynamic features of space environment in the heliosphere, the geo-magnetosphere, and the
earth’s atmosphere. In particular, transient perturbations in solar wind plasma, interplanetary magnetic field, and energetic
charged particle (cosmic ray) fluxes near 1 AU in the heliosphere have been discussed. Transient variations in magnetic activity
in geo-magnetosphere and solar modulation effects in the heliosphere have also been studied. Emphasis is on certain features
of transient perturbations related to space weather effects. Relationships between geomagnetic storms and transient modulations
in cosmic ray intensity (Forbush decreases), especially those caused by shock-associated interplanetary disturbances, have
been studied in detail. We have analysed the cosmic ray, geomagnetic and interplanetary plasma/field data to understand the
physical mechanisms of two phenomena namely, Forbush decrease and geomagnetic storms, and to search for precursors to Forbush
decrease (and geomagnetic storms) that can be used as a signature to forecast space weather. It is shown that the use of cosmic
ray records has practical application for space weather predictions. Enhanced diurnal anisotropy and intensity deficit of
cosmic rays have been identified as precursors to Forbush decreases in cosmic ray intensity. It is found that precursor to
smaller (less than 5%) amplitude Forbush decrease due to weaker interplanetary shock is enhanced diurnal anisotropy. However,
larger amplitude (greater than 5%) Forbush decrease due to stronger interplanetary shock shows loss cone type intensity deficit
as precursor in ground based intensity record. These precursors can be used as inputs for space weather forecast. |
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Keywords: | Space weather geomagnetic storm cosmic ray Forbush decrease interplanetary shock coronal mass ejection |
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