TY - JOUR AU - Lan, Hoàng Thái AU - Trang, Nguyễn Thu AU - MACDOUGALL, JOHN PY - 2011/12/22 Y2 - 2024/03/28 TI - SO SÁNH SỰ XUẤT HIỆN CỦA SPREAD F XÍCH ĐẠO TỪ TRONG NĂM MẶT TRỜI HOẠT ĐỘNG TRUNG BÌNH (2003) VÀ HOẠT ĐỘNG YẾU (2005) JF - Vietnam Journal of Earth Sciences JA - Vietnam J. Earth Sci. VL - 33 IS - 2 SE - Articles DO - 10.15625/0866-7187/33/2/287 UR - https://vjs.ac.vn/index.php/jse/article/view/287 SP - 126-133 AB - <p><strong>The occurrence of equatorial spread F over Ho Chi Minh City in years 2003 and 2005</strong></p><p>This paper presents results of the study of spread F based on the ionograms obtained at Ho Chi Minh City (Vietnam)<br />for year 2003 (medium solar activity) and year 2005 (weak solar activity) under quiet geomagnetic conditions.<br />The characteristics of Spread F over Vietnam showed a tendency with a decrease and later occurrence in the year of weaker solar activity. The seasonal variations showed maximum in March - April and minimum in December.<br />The Range Spread F (Fs_Q) that related to scintillations of radio signals between satellites and ground stations occurred pre-midnight and appeared more in February, March and April. The time of appearance of the Fs_Q in the year 2005 occurred later than in the year 2003.<br />The Frequency Spread F (Fs_F) occurred post-midnight and showed maximum of occurrence during equinoxial months.<br />These results were also compared with results of other equatorial stations.</p> ER -