This manuscript presents an overview of results obtained during the solar activity cycle 23 & 24 from 1997-2013 on short term asymmetric cosmic ray intensity decreases 4%, and how it relate to solar flares and interplanetary shocks. For this work we have obtained the data of cosmic ray intensity decreases and other parameters from ground-based neutron monitors (NMs) and NCEI respectively. We have observed 74 asymmetric cosmic ray decreases in our list out of which 69(93.24%) have been identified as being associated with x-ray solar flares of different categories. Out of which 16 (23.19%) are found to be associated with X class X-ray solar flares, 36(52.17%) associated with M class X-ray solar flares, 13(18.84%) found to be associated with C class X-ray solar flares and 04(5.7%) are found to be associated with B class X-ray solar flares. Further we have found that out of 74 asymmetric cosmic ray intensity decreases 60(81.08%) have been found to be associated interplanetary shocks. The associated interplanetary shocks are forward shocks and observed that majority of interplanetary shocks following the onset of asymmetric cosmic ray intensity decreases (Fds). Out of 60 cosmic ray intensity decreases arrival time of 37(61.66%) interplanetary shocks have been found after the onset time of asymmetric cosmic ray intensity decreases, The arrival time of 20(33.33%) interplanetary shocks have been found before the onset time of asymmetric cosmic ray intensity decreases and onset time of 03(5%) asymmetric cosmic ray decreases are common to arrival time of interplanetary shocks. We perform a statistical analysis to find out the correlation between the magnitude cosmic ray intensity decreases with M and X class solar flares and obtain the correlation with correlation coefficient of 0.22, 0.77 respectively. Other B and C class flares are not correlated with Fds.
Keywords: – cosmic ray intensity decreases, asymmetric cosmic rays, solar flares, interplanetary shocks.
Preetam Singh Gour1, Shiva Soni2*