Daytime mid-latitude F-layer Q-disturbances: A formation mechanism.

Negative and positive near noontime prolonged (≥3 hours) F-layer Q-disturbances with deviations in NF > 35% occurred at Rome have been analyzed using aeronomic parameters inferred from f (plasma frequency at 180 km height) and fF observations. Both types of NF perturbations occur under quiet (daily Ap < 15 nT) geomagnetic conditions. Day-to-day atomic oxygen [O] variations at F-region heights specify the type (positive or negative) of Q-disturbance.