The occurrence of equatorial spread F (ESF) at Biak (01deg S.Lat ,135 deg E.Long)

Kontribusi Fisika Indonesia
Vol. 12, No.3, Juli 2001

Buldan Muslim1), Sarmoko Saroso1) dan The Houw Liong2)
1)Pusat Pemanfaatan Sains Antariksa LAPAN
Jl. Dr. Junjunan 133 Bandung 40173
2) Departemen Fisika FMIPA Insitut Teknologi Bandung

Abstract
The occurrence of equatorial spread F (ESF) at Biak (01deg S.Lat.,135deg E.Long.) , during March and April has been investigated on daily basis in sunspot medium years 1992 in terms of the growth rate of irregularities by the gravitational Rayleigh-Taylor (GRT) instability mechanism which includes the gravitational and cross-field instability terms. The occurrence statistics of ESF at Biak are examined in relation to maximum of h’F after sunset, rate of h’F and fluctuation of rise as well as with solar and magnetic activity conditions. It is found that the day-to-day variation of ESF occurrence at Biak can be accounted generally for on the basis of the GRT mechanism. On the basis of March data from 1992 – 1995 occurrence of ESF decrease with decreasing solar activity.

Keywords: Ionosphere, Instability, Spread F