We have observed 74 short term asymmetric cosmic ray intensity decreases for the period 1997-2013, which are associated with geomagnetic storms and solar wind plasma parameters (temperature, velocity). Out of 74, 62 events are found to be associated with geomagnetic storms. Further out of 74 events 71 events are associated with jump in solar wind plasma temperature (JSWT) and 67 events are associated with jump in solar wind plasma velocity (JSWV). From the analysis we observed the positive correlation between the magnitude of asymmetric cosmic ray decreases and magnitude of geomagnetic storms with correlation coefficient of 0.60. Further we find the positive correlation with correlation coefficients 0.42 and 0.33 between magnitude of asymmetric cosmic ray decreases with peak value of JSWT events and magnitude of JSWT events respectively. Again from the analysis positive correlation is found with correlation coefficients 0.38 and 0.23 between magnitude of asymmetric cosmic ray decreases with peak value of jump in solar wind plasma velocity (JSWV) events and magnitude of JSWV events respectively.
Keywords: – cosmic ray intensity decreases, solar wind plasma parameters, geomagnetic storms.
Preetam Singh Gour, Shiva Soni & Arun Kumar