Secular and Seasonal Variations of Transfer Functions at Kakioka from Mar. 1977 to Apr. 1981
Sano, Y & Nakajima, S.
Abstract
In this paper, secular and seasonal variations of various transfer functions at Kakioka have been analyzed based on the data during 50 months (four years) from Mar. 1977 to Apr. 1981. Monthly means of transfer functions were mainly used for these analyses.
There are various types of secular variations of transfer functions which are more or less different for different transfer functions and/or for different periods. The variations show in general a sine curve-like change rather than a linear one. It may be better to consider that almost all secular variations obtained here are not of a long-term, but of a short-term like an about six-year periodic change in A transfer function reported by Yanagihara and Nagano (1976).
The seasonal variations of Au, Av and Bv transfer functions resemble as a whole one another, showing an annual variation with a maximum in summer and a minimum in winter. Av transfer functions for almost all period bands analyzed here show the most predominant seasonal variations among four kinds of transfer functions, the mean Fourier amplitude amounting to about 0.02. Bu's show more predominantly a semi-annual variation rather than the annual one.
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