F-layer peak height variation near the equatorial anomaly crest during moderate solar activity

The variations of F-layer peak density height or h_max for March, June, September and December during moderate solar activity period (2006 - 2007) have been analyzed to describe the short term variability of this parameter near the southern crest of equatorial anomaly. The parameters were derived from ionograms obtained from the Parit Raja (Lat. 1°52´N, Long. 103°48´E, magnetic dip 14.3°) ionosonde station. The results show that hmax is greater during midday around 1200 to 1400 LT and slowly decreases in the evening until the lowest level at midnight. The seasonal peak ranges from 400 to 600 km with the highest level observed in December solstice (550 km) and the minimum in June solstice (430 km). The equinoxes months peak values are between 500 and 550 km. h_max is lowest during midnight (2400 LT) with values range from 230 to 300 km. Highest variability is obtained in March equinox while June solstice shows very minimal variability in h_max.