Ionization balance in the D region

Attempts have been made to compare the mesospheric electron density values derived from multifrequency radio wave absorption data for a low-latitude station with the ionization production rates of O2+ and NO+ under different conditions of solar zenith angles and solar activity levels. For both 80 km and 90 km the relation q ∝ N is found to be a better approximation than the simple recombination type of relation q ∝ N2. In addition, the situation at 80 km appears to be more complicated and indicates the possibility of a lower NO density than that implied in the observation by Meira (1971).