Earth Planets Space, Vol. 61 (No. 4), pp. 385-395, 2009
M. A. Abdu and C. G. M. Brum
Instituto Nacional de Pesquisas EspaciaisINPE São José dos Campos, SP, Brazil
(Received October 9, 2007; Revised February 1, 2008; Accepted February 1, 2008; Online published May 14, 2009)
Dynamical, electro-dynamical and electrical coupling processes originating from upward propagation of atmospheric waves, and magnetosphere-ionosphere interaction are responsible for the large degree of variabilities observed in the low latitude ionosphere. One of the most outstanding aspects of its phenomenology is related to the sunset electrodynamical processes responsible for the evening enhancements in zonal and vertical electric fields and the associated spread of F/plasma bubble irregularity development. Recent observational results have provided evidence of significant contribution to their quiet time variability arising from thermospheric wind patterns, upward propagating planetary waves and possibly sporadic E layers. This paper provides an overview and some new results on planetary wave coupling with the equatorial F region, the E layer conductivity as key connecting mechanism, a possibly interactive role by sporadic E layers, and the resulting day-to-day variability in the evening prereversal electric field enhancements with consequences on spread F development.
Key words: Vertical coupling, atmosphere-ionosphere, spread F, planetary waves, sporadic E layers, prereversal electric field.