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) through the generalized Rayleigh-Taylor instability mechanism, the importance of dynamical parameters is examined by means of a nonlinear numerical simulation technique. The investigation reveals that agencies like downward wind and eastward electric field of measured magnitudes accelerate the evolutionary process of ESF even beyond 350 km height, where according to the linear theories they are considered to be less significant. It is also shown that the acceleration must be due to the presence of in-situ winds or electric fields. The variabilities in the occurrence characterstic of ESF are discussed in connection with the possible day-to-day variabilities of vertical winds