The variation of critical frequency of E layer over Chumphon, Thailand - Poramintra Wongcharoen; Prasert Kenpankho; Kasemsuk Sepsirisuk; Pornchai Supnithi; Suthichai Noppanakeepong; Somkiat Lerkvaranyu; Takuya Tsugawa; Tsutomu Nagatsuma (My University, 2013)
Keywords: Critical frequency; International Reference Ionosphere; Variation (astronomy); Magnetic dip; Ionosphere and magnetosphere dynamics