%0 Journal Article
%T Dependence of Time Derivative of Horizontal Geomagnetic Field on Sunspot Number and aa Index
%J Frontiers in Science
%@ 2166-6113
%D 2012
%I 
%R 10.5923/j.fs.20120201.01
%X This work investigated the interrelationship between the monthly means of time derivatives of horizontal geomagnetic field (dH/dt), sunspot number (Rz) and aa index for period of substorms (-90nT-1800nT) during the years 1990-2009. 232 substorms were identified during the period of study. Time derivative of horizontal geomagnetic field (dH/dt) used as proxy for geomagnetic induced current (GIC), exhibited high positive correlation with sunspot number (0.86) and aa index (0.8998). 92.665% of the obtained geomagnetic activity is explicable by the combined effect of sunspot number aa index. The distribution of substorms as a function of years, gives a strong support for the existence of geomagnetic activity increases which implies that as the sunspot number increases the base level of geomagnetic activity increases.
%K Solar Activity
%K Time Derivatives of Geomagnetic Fields
%K Sunspot Number
%K Substorms
%U http://article.sapub.org/10.5923.j.fs.20120201.01.html