The influence of the interplanetary medium on SuperDARN radar scattering occurrence

The effects of the characteristics of the interplanetary medium on the rada r scattering occurrence. related to the whole array of SuperDARN radars ins talled in the Northern Hemisphere, have been studied over a two-year period . Statistically significant correlations of the variation of the scattering occurrence are found with the merging electric held and with the negative B-z component of the interplanetary magnetic field, independent of the seas onal period considered. This result demonstrates that the merging rate (and in particular the reconnection process) between the interplanetary magneti c field and the magnetosphere is a relevant factor affecting the occurrence of scattering. For comparison, we note that no statistically significant c orrelations are obtained when the interplanetary ion density or the solar w ind speed are considered, although also these variables affect to a small d egree the scattering occurrence variation. The study of the latitudinal and magnetic local time dependence of the observations shows an association be tween the considered correlation and the location of the auroral oval and t he cusp/cleft region.