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On the reduced geoeffectiveness of solar cycle 24: A moderate storm perspective
Author(s) -
Selvakumaran R.,
Veenadhari B.,
Akiyama S.,
Pandya Megha,
Gopalswamy N.,
Yashiro S.,
Kumar Sandeep,
Mäkelä P.,
Xie H.
Publication year - 2016
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2016ja022885
Subject(s) - geomagnetic storm , coronal mass ejection , solar cycle 23 , solar cycle 22 , solar cycle 24 , atmospheric sciences , solar cycle , storm , interplanetary spaceflight , solar flare , environmental science , physics , solar wind , meteorology , astrophysics , magnetic field , quantum mechanics
The moderate and intense geomagnetic storms are identified for the first 77 months of solar cycles 23 and 24. The solar sources responsible for the moderate geomagnetic storms are indentified during the same epoch for both the cycles. Solar cycle 24 has shown nearly 80% reduction in the occurrence of intense storms whereas it is only 40% in case of moderate storms when compared to previous cycle. The solar and interplanetary characteristics of the moderate storms driven by coronal mass ejection (CME) are compared for solar cycles 23 and 24 in order to see reduction in geoeffectiveness has anything to do with the occurrence of moderate storm. Though there is reduction in the occurrence of moderate storms, the Dst distribution does not show much difference. Similarly, the solar source parameters like CME speed, mass, and width did not show any significant variation in the average values as well as the distribution. The correlation between VB z and Dst is determined, and it is found to be moderate with value of 0.68 for cycle 23 and 0.61 for cycle 24. The magnetospheric energy flux parameter epsilon ( ε ) is estimated during the main phase of all moderate storms during solar cycles 23 and 24. The energy transfer decreased in solar cycle 24 when compared to cycle 23. These results are significantly different when all geomagnetic storms are taken into consideration for both the solar cycles.