Solar activity linked variabilities in the Thermospheric meridional winds and their control on the occurrence of Equatorial Spread-F
Abstract
The thermospheric wind system, through interactions with the ionospheric layers control many of the electrodynamic processes of the equatorial ionosphere thermosphere system; the occurrence of equatorial Spread F (ESF) being a manifestation of one of these processes. One of the important aspects of a plausible linkage of Thermospheric meridional winds with the ESF has recently been identified as through the polarity of the winds just before the onset of ESF. The importance of winds of equatorward/poleward polarity would matter only in relation with the Fregion base height as to whether it is below or above a characteristic- critical height. It is found that there is a strong solar cycle modulation of the critical base height of the F-region by as much as +/-50km for the occurrence of ESF with the associated meridional winds also responding to the solar variabilities. The solar activity dependence of the meridional wind characteristics and the F-region critical height variations are discussed in detail in relation to their possible roles in the variations of ESF occurrence.
- Publication:
-
34th COSPAR Scientific Assembly
- Pub Date:
- 2002
- Bibcode:
- 2002cosp...34E1381S