On the Analysis of the Data for the Freezing of Lake Suwa

Abstract

As an example of application of Takahasi's method of the determination of period and damping ratio of the irregular motion of an oscillating body, we made some investigations on the periodicity of the dates of freezing of Lake Suwa.
In the first place the method was applied to each of four sections into which the whole period of records was divided and next to the whole interval.
As we can thought that the curve which was obtaind by the method expresses free oscillation of the system, so that we calculated the period and the damping ratio from that curve. Besides this, other methods, such as partial means and the normal statistical method, namely the method of correlation, have also been tried, We obtained, as a conclusion of these analysis, that there exist 3 years and 33 years periodicity in the dates of freezing of Lake Suwa.