Earth, Atmosphere & Environment Sciences
Title : | Understanding the generation of the late-night plasma bubble and irregularities in the June solstice of low solar condition |
Area of research : | Earth, Atmosphere & Environment Sciences |
Principal Investigator : | Mr. Soujan Ghosh, National Atmospheric Research Laboratory, Tirupati, Andhra Pradesh |
Timeline Start Year : | 2022 |
Timeline End Year : | 2024 |
Contact info : | soujanghosh89@gmail.com |
Details
Executive Summary : | Equatorial Spread F (ESF) is an irregularity in the ionospheric F region observed during post-sunset time on equinox conditions in most longitude sectors. ESF occurs during the equinox and December solstice when the prereversal enhancement (PRE) is well developed, producing Generalized Rayleigh-Taylor (GRT) instability when the F layer is uplifted by the PRE. The vertical density gradient in the bottom side of the F region is sharp due to rapid recombination in the bottom side of the F region. These conditions make the post-sunset period ideal for the generation of equatorial plasma bubbles (EPBs). The upward component of E X B drifts is the main factor controlling GRT instability growth. After generation, these bubbles grow non-linearly in the topside ionosphere due to the polarization electric field and generally drift in the eastward direction. In the Asian region, the highest number of EPBs are observed during equinox months due to the near-zero or less declination angle. However, in the South American region, where the declination angle is negative, the most number of EPBs are observed during the December solstice. The generation mechanism of late-night EPBs is not clearly known, but several attempts have been made to study possible ionospheric conditions for their development. The PRE magnitude peaked 1 hour later during the June solstice than for other seasons. The delay in the peak PRE is considered a remnant of the PRE that is supposed to occur after the post-sunset time. To understand the nature and generation mechanism of EPBs in late-night hours at low latitude, multi-instrumental observation and interpretation of F region irregularities are necessary and a topic of great interest. |
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