Inferred secular variation of the heliospheric magnetic field

66-69There is a considerable interest in the long-term influence of solar activity on terrestrial climate. Earlier work, by using correlation between geomagnetic aa index and galactic cosmic ray counts, inferred that the radial component of the interplanetary magnetic field at 1 A.U. increases secularly. However, our results show that there is no correlation between the geomagnetic aa index and galactic cosmic ray counts for time periods 1964-1986, 1986-1996 and 1997-2010. Averaging has to be very carefully dealt with when examining the aa index and other parameters that depend upon the sign of interplanetary magnetic field as averaged values and the most probable values may not be the same. Low values of the correlation coefficients between cosmic ray counts and the CME rate for time period 1996-2009 also has been obtained. This low values of the correlation coefficients is due to high frequency of CME