Abstract
Using a preliminary three-month table of IAGA, the hourly frequency of pc, F, which is first expressed by the number of pc appeared in each one hour interval in local time, is calculated at each of the fourteen observatories in Europe-Africa and Japan-Australia longitudinal zones, for each month and each season during the period from October, 1957 to June, 1958. It is found that for each season the mean maximum hour interval of the frequency falls around 9-11hr in local time for the most observatories. And secondarily the ratio Fm/F is introduced, and it shows a remarkable dependency on the geomagnetic latitude, though the most important regions both equatorial and auroral zones can not be introduced, where Fm is the maximum value of F and F the mean value of F for each season.
It is also clarified by superposed-epoch method that the principal maximum peaks of daily numbers of observatories listed in the table appear one or two days after those of ΣKp during the whole period. The inverse relation is also checked.
It is suggested from these results that the, outer atmosphere may become most sensitive in more extended depth than usual to the impinging solar agency over the earth within one or two days after the geomagnetic disturbances, probably in the higher geomagnetic latitudes.
