Mid-Latitude Ionospheric Scintillations and Geomagnetic Activity

抄録

The effects of geomagnetic activity on the mid-latitude scintillation have been investigated by using VHF radio waves from the geostationary satellite ETS-II. Statistics of nearly one-year data reveal that (1) geomagnetic activity dependence of the scintillation around Japan has properties similar to those of the equatorial scintillation; i.e., the occurrence tends to be suppressed with the increase in geomagnetic activity in summer (the season of high scintillation activity), especially in the premidnight hours, and (2) there is a negative correlation between K_p index and the scintillation occurrence in the range of 0≤K_p≤4, while the correlation becomes positive in the range of K_p≥5, so that we may have two peaks of the occurrence at K_p=1 or 2, and K_p≥8. The former peak depends obviously on season, whereas the latter does slightly. These results will give evidence that the scintillation tends to occur more frequently during severe geomagnetic storms in any season.