SECULAR AND SEASONAL CHANGES IN TRANSFER FUNCTION AT GUANGZHOU GEOMAGNETIC OBSERVATORY

Time changes in transfer functions of short period geomagnetic variations in 28 years from 1960 through 1987 are studied, systematically and in detail in this paper. The results indicate that : (1) It is evident that seasonal and secular changes in the transfer functions A at exists the Guangzhou geomagenetic observatory. The character for seasonal change are large in summer and smaller in winter with main cycles of 12 months and 6 months. The character for secular change is a descend with a rate of 0.0025 per year. The seasonal and secular changes in transfer functions B are not evident. (2)The direction of Parkinson vector at Guangzhou geomagnetic observatory is clearly affected by the ocean, and is associated with coastal effect. (3)The values of transfer functions A and B are related to geomagnetic activity at = 0.05. Secular change is not related to geomagnetic activity, maybe it is affected in a great measure by earth conductivity change.