TY - JOUR AU - Lan, Trần Thị AU - Cường, Đào Thế PY - 2014/02/22 Y2 - 2024/03/29 TI - Some characteristic of equatorial spread F at Phu Thuy over a solar cycle JF - Vietnam Journal of Earth Sciences JA - Vietnam J. Earth Sci. VL - 35 IS - 3 SE - Articles DO - 10.15625/0866-7187/35/3/3699 UR - https://vjs.ac.vn/index.php/jse/article/view/3699 SP - 265-271 AB - This paper presents the research results of the occurrence of equatorial spread F at Phuthuy ionospheric observatory in Hanoi over a solar cycle (1962-1979). The most common type of spread-F observed at Phuthuy are the range spread type (Fs_Q) and the frequency spread type (Fs_F). In both phases, the maximum Fs occurs after midnight (maximum at 1-2 LT). The seasonal variation of Fs occurrence showed peaks at equinox months during the maximum sunspot years, but during the moderate and weak sunspot years there was a peak in summer. Range spread type<br />occurs concentratively on the before midnight period, on the equinox month and on the maximum sunspot years.<br />Frequency spread type occurs concentratively on the after midnight period, on the summer and on the moderate and weak solar activily. The characteristic features and the variations of Spread F occurrence at Phuthuy, Hanoi (13.02°N magnetic latitude) are similar from those at Ahmedabad, Indian (15.00°N magnetic latitude). ER -