Abstract
This paper presents study of storm effect on nighttime enhancement at low latitude station Jicamarca. Jicamarca is an ionospheric station along the anomaly trough in the American sector. For this purpose hourly values of the critical frequency (foF2) parameter are taken at low latitude station Jicamarca (12°S, 76.9°W; dip 0.28°). In the study, 39 severe storms were selected during the period2002 to 2014 based on the Dst index. With Dst ≤ −100 nT is considered to be as severe storm. We have analyzed all the characteristics of nighttime enhancement at Jicamarca such as yearly mean amplitude, time of peak and duration of enhancement. To determine the seasonal effects, we grouped all data into three seasons’ winter, summer and equinox using the four months of data for each season equinox (March, April, September and October), winter (January, February, November and December) and summer (May, June, July and August). It has been found in the study that the nighttime enhancement of foF2 is affected by stormsat Jicamarca. It can be observed from the analysis of seasonal variation of mean amplitude during major storm and disturbed nights that mean amplitude of nighttime foF2 is higher in equinox and lowest in summer. Maximum peaks are observed during 22: 00 LT during both major storms and disturbed days. The outcome presented in the study provide comprehensive image of the effect of storm on nighttime enhancement.
Highlights
Ionospheric storms are large-scale disturbances of the ionospheric structure and make it, dynamics erupted by a Coronal Mass Ejection from the sun
Dst ≤ −100 nT is considered as major storm, due to lack of availability of data 39 storms are taken for study
The outcome presented in this study provide comprehensive image of the effect of storm on nighttime enhancement
Summary
Ionospheric storms are large-scale disturbances of the ionospheric structure and make it, dynamics erupted by a Coronal Mass Ejection from the sun. The possible processes which might contribute to the magnetic storm causing ionospheric variations are: Electromagnetic drift processes: this processes associated with storm time electric field In this process, the magnetospheric convective electric field couples into the polar region where it quickly penetrates into the low and equatorial latitudes within a few seconds [8]. In enhanced thermospheric circulation processes, the storm time particle precipitation in the auroral region produce a series of energy transfer events through disturbed winds and tides, which propagate both toward the pole and the equator from the source region [10]. These thermospheric disturbances generate acoustic gravity waves which are visible as travelling atmospheric disturbances and travelling ionospheric disturbances. Wave like perturbation are excited by joule heating [17]
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