Occurrence of the dayside three-peak density structure in the F2- and the topside ionosphere | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  Occurrence of the dayside three-peak density structure in the F2- and the topside ionosphere

Type de publication:

Journal Article

Source:

Journal Geophysical Research - Space Physics, Volume 121, Ticket 7 (2016)

Résumé:

<p><span style="color: rgb(51, 51, 51); font-family: 'Open Sans', Arial, Helvetica, 'Lucida Sans Unicode', sans-serif; font-size: 16px; background-color: rgb(249, 249, 249);">In this work, we discuss the occurrence of the dayside three-peak electron density structure in the ionosphere. We first use a set of ground-based and satellite-borne instruments to demonstrate the development of a large-amplitude electron density perturbation at the recovery phase of a moderate storm of 11 October 2008. The perturbation developed in the&nbsp;</span><em style="margin: 0px; padding: 0px; border: 0px; outline: 0px; font-size: 16px; vertical-align: baseline; color: rgb(51, 51, 51); font-family: 'Open Sans', Arial, Helvetica, 'Lucida Sans Unicode', sans-serif; background-position: 0px 0px;">F</em><span style="line-height: 0; bottom: -0.25em; margin: 0px; padding: 0px 1px; border: 0px; outline: 0px; font-size: 0.688em; vertical-align: baseline; position: relative; color: rgb(51, 51, 51); font-family: 'Open Sans', Arial, Helvetica, 'Lucida Sans Unicode', sans-serif; background-position: 0px 0px;">2</span><span style="color: rgb(51, 51, 51); font-family: 'Open Sans', Arial, Helvetica, 'Lucida Sans Unicode', sans-serif; font-size: 16px; background-color: rgb(249, 249, 249);">&nbsp;and low topside ionospheric regions over the American sector; it was concentrated on the north from the equatorial ionization anomaly (EIA) but was clearly separated from it. At the&nbsp;</span><em style="margin: 0px; padding: 0px; border: 0px; outline: 0px; font-size: 16px; vertical-align: baseline; color: rgb(51, 51, 51); font-family: 'Open Sans', Arial, Helvetica, 'Lucida Sans Unicode', sans-serif; background-position: 0px 0px;">F</em><span style="line-height: 0; bottom: -0.25em; margin: 0px; padding: 0px 1px; border: 0px; outline: 0px; font-size: 0.688em; vertical-align: baseline; position: relative; color: rgb(51, 51, 51); font-family: 'Open Sans', Arial, Helvetica, 'Lucida Sans Unicode', sans-serif; background-position: 0px 0px;">2</span><span style="color: rgb(51, 51, 51); font-family: 'Open Sans', Arial, Helvetica, 'Lucida Sans Unicode', sans-serif; font-size: 16px; background-color: rgb(249, 249, 249);">&nbsp;region height, the amplitude of the observed perturbation was comparable or even exceeded that of the EIA. Further analysis of the observational data together with the Coupled Thermosphere Ionosphere Plasmasphere Electrodynamics model simulation results showed that a particular local combination of the thermospheric wind surges provided favorable conditions for the generation of the three-peak EIA structure. We further proceed with a statistical study of occurrence of the three-peak density structure in the ionosphere in general. Based on the analysis of 7 years of the in situ data from CHAMP satellite, we found that such three-peak density structure occurs sufficiently often during geomagnetically quiet time. The third ionization peak develops in the afternoon hours in the summer hemisphere at solstice periods. Based on analysis of several quiet time events, we conclude that during geomagnetically quiet time, the prevailing summer-to-winter thermospheric circulation acts in similar manner as the storm-time enhanced thermospheric winds, playing the decisive role in generation of the third ionization peak in the daytime ionosphere.</span></p>