THE USE OF SPREAD-F AND SPORADIC-E OBSERVATIONS IN INTERPLANETARY SCINTILLATION FORECASTS OF GEOMAGNETIC-ACTIVITY

Previous work has shown that interplanetary scintillation (IPS) observ ations produce a poor forecast for geomagnetic activity. An explanatio n of some of the problems encountered would be the existence of an add itional scintillation signal, e.g. of ionospheric origin. Hoping to re duce the effect of any ionospheric activity, and hence improve the for ecast, local ionospheric observations were used in selecting IPS data. The success of geomagnetic forecasts based on these data was calculat ed, in this case by correlating the scintillation level with Ap. The c oefficient at one day lag increased from 0.40+/-0.04 to 0.62+/-0.05, b ut did not represent a significant improvement in forecast quality sin ce the data were heavily biased towards periods of low Ap.