Long-term behavior of annual and semi-annual Sq variations

We have examined the long-term behavior (solar-cycle time scale) of annual and semi-annual S-q variations. We analyzed geomagnetic data observed at locations that were roughly geographically conjugate in the west Pacific region (Kakioka and Gnangara) during the last five solar cycles (1953-2006). Three-year compound data were constructed for each station for each year. The stationary component {(S) over bar (q)}(0), annual component {(S) over bar (q)}(1), and the semi-annual component {(S) over bar (q)}(2), of the S-q variations were derived from the compound data. The solar-activity dependence of the derived three components was evaluated in comparison with the sunspot number ((R) over bar). It was found that the amplitudes of all three components ({(S) over bar (q)}(0), {(S) over bar (q)}(1) and {(S) over bar (q)}(2)) have a positive linear correlation with the sunspot number. The most remarkable result is that the linear regression coefficient for {(S) over bar (q)}(0) is much bigger than those of {(S) over bar (q)}(1) and {(S) over bar (q)}(2). The physical mechanisms involved are yet to be understood.