EFFECTS OF VERTICAL WINDS AND ELECTRIC-FIELDS IN THE NONLINEAR EVOLUTION OF EQUATORIAL SPREAD-F

In view of the present understanding of Equatorial Spread F (ESF) thro ugh the generalized Rayleigh-Taylor instability mechanism, the importa nce of dynamical parameters is examined by means of a nonlinear numeri cal simulation technique. The investigation reveals that agencies like downward wind and eastward electric field of measured magnitudes acce lerate the evolutionary process of ESF even beyond 350 km height, wher e according to the linear theories they are considered to be less sign ificant. It is also shown that the acceleration must be due to the pre sence of in-situ winds or electric fields. The variabilities in the oc currence characterstic of ESF are discussed in connection with the pos sible day-to-day variabilities of vertical winds