THE EFFECTS OF ELECTRIC-FIELD AND RING CURRENT ENERGY INCREASES ON F-LAYER IRREGULARITIES AT AURORAL AND SUBAURORAL LATITUDES

A model of the dynamics of magnetic storms is proposed which describes the effects of magnetospheric activity on irregularities at F layer heights for auroral and subauroral latitudes. For high latitudes the initial phase of the storm dynamics first affects auroral latitudes, and then the effects descend to what were subauroral and middle latitudes. The effects weaken as the convective electric field boundary moves equatorward. In the second stage of the storm, i.e., the recovery period, the ring current plays a leading role at subauroral latitudes. The ring current, which has acted as a reservoir for ionospheric and solar wind ions, decays. In this recovery phase the sources of energy producing the irregularities at subauroral latitudes are the ions in the ring current. This new synthesis of storm effects uses illustrations from a number of magnetic storms with observations ranging from December 1971 to March 1989, primarily in years of high solar flux. The data illustrate the concept of two stages of irregularity development. (1) The initial descent and weakening of the effects of the electric field changes and (2) ring current decay which produces the conditions for the generation of the irregularities at subauroral latitudes.