Study of variation in the lower ionospheric reflection height with polar day length at Antarctic station Maitri: Estimated with tweek atmospherics

In the present paper investigations are made on the lower ionosphere with the help of observed tweek atmospherics at the Indian Antarctic research station Maitri during the second half of austral summer (January–March of 2003 and 2005). The variations in the lower ionospheric reflection height are found to be in correspondence with the sunrise and sunset at Maitri. The results indicate that the tweek atmospherics are helpful in tracking the changes taking place in the lower ionospheric height through the day‐night boundary. The ionospheric reflection height estimated using the cutoff frequency of fundamental (first‐harmonic or first‐mode) tweek atmospherics ranges from ∼64 to ∼79 km with a maximum calculated error of ±2.7 km. The recordings were carried out from 1800 to 0600 UTC. The analysis shows that the average cutoff frequency for the fundamental tweek atmospherics and hence the ionospheric reflection height varies from the months of January to March in accordance with the sunrise and sunset.