Abstract
The relationship between the F2-layer critical frequency and solar wind parameters during magnetic storm sudden commencement (SSC) and main phase periods for intense (IS) and very intense (VIS) class of storms is investigated. The analysis covers low- and mid-latitude stations. The effects of ionospheric storm during SSC period is insignificant compared to the main phase, but can trigger the latter. The main phase is characterized by severe negative storm effect at both latitudes during VIS periods while it is latitudinal symmetric for IS observations. The IS reveal positive/negative storm phase in the low-/mid-latitudes, respectively. Ionization density effect is more prominent during VIS events, and is attributed to large energetic particle and solar activity input into the earth magnetosphere. However, ionospheric effect is more significant at the low-latitude than at the mid-latitude. Lastly, ionospheric storm effect during a geomagnetic storm may be related to the combinational effect of interplanetary and geomagnetic parameters and internal ionospheric effect, not necessarily the solar wind alone.
Highlights
The effects of magnetic storms on the ionosphere are complex and deviate greatly from average ionospheric behavior
The critical observation of the hemispheric dependence shows that the ionospheric storm effect is more pronounced in the Southern Hemisphere than in the Northern Hemisphere. This intense negative storm record extends to the recovery phase and decreases with time. This negative ionospheric storm effect during the main phase may be connected with a prompt eastward penetration of electric field (PPEF) and equatorward neutral winds (Balan et al 2010) and change in thermospheric composition generated during geomagnetic storms at auroral latitude which are transported to lower latitudes by the disturbed thermospheric wind circulation produced by joule heating and particle precipitation in the auroral region (Prölss 1995)
We found here for the magnetic cloud (MC) driver gas, a low plasma beta of 0.03, low proton density of 9.7, high north-south IMF component, and low plasma temperature, which are common interplanetary coronal mass ejections (ICME) driver characteristics
Summary
The effects of magnetic storms on the ionosphere are complex and deviate greatly from average ionospheric behavior. Chukwuma (2007) asserted that the difficulty with the explanation of these phenomena is because in the studies of ionospheric storms it is assumed that the beginning of the disturbance is defined by storm sudden commencement (SSC) or main phase onset (MPO), which as a scheme restricts the geoeffectiveness of the solar wind to post-onset time. These foreclose the explanation of any aspect of the morphology of ionospheric storms whose origin precedes the onset reference time. This work attempts to find the relationship between ionospheric and solar wind phenomena during SSC and main phase of geomagnetic storms at some selected low- and midlatitude stations
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