Regional map of the F2-layer critical frequency over Southeast Asia

This paper presents the development of a regional ionospheric F2 layer critical frequency (foF2) map over Southeast Asia using parabolic curve fitting. To produce the map, the foF2 values measured by the ionosonde measurement at Chiang Mai, Chumphon and Kototabang are used as the input of the ionospheric map. To examine the performance of the foF2 mapping, our local maps and the global maps (IRI-Plas 2015 online under IONOLAB website) are compared at five stations over Southeast Asia, including Chiang Mai, Chumphon, Kototabang, Bac Lieu, and Phu Thuy. The results on equinox day (20
^th
March) in 2009 and 2015 are analyzed. The results show that our map produces foF2 values close to the observed data while the global map underestimates the measured data in 2009 and it overestimates in 2015. The results of this paper are important for managing and designating the maximum usable frequency (MUF) of HF communication systems over Southeast Asia region.