131842.fig.001
Figure 1: Longitudinal distributions of the critical frequency foF2 obtained by IS-338 topside sounder (Intercosmos-19 satellite) at the latitude 3N for the fixed local time (05-06 LT). Bold line (1): averaged quiet time distribution; dash-dot line (2): distribution obtained for 14 July 1980; dashed line (3): distribution obtained on 15 July 1980.