The N2/O density ratio as measured by the Esro 4 satellite is used to investigate seasonal changes in the latitudinal structure of nine disturbance events. A comparison of summer and winter data reveals that (1) whereas in summer the N2/O disturbance zone may extend from the polar to the low-latitude regions, it is restricted to the higher latitudes in winter; (2) whereas in summer the increase in the N2/O disturbance at the lower-latitude boundary is a gradual one, rather steep increases are frequently observed during winter; and (3) whereas in summer perturbations are of moderate magnitude, fairly large disturbance effects are commonly seen in winter. It is suggested that the interaction of seasonal and magnetic storm induced winds is responsible for the differences observed.