@Article{AbduKherSous:2020:SoMiMa,
author = "Abdu, Mangalathayil Ali and Kherani, Esfhan Alam and Sousasantos,
J.",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto
Nacional de Pesquisas Espaciais (INPE)} and {Instituto
Tecnol{\'o}gico de Aeron{\'a}utica (ITA)}",
title = "Role of bottom-side density gradient in the development of
equatorial plasma bubble/spread F irregularities: solar minimum
and maximum conditions",
journal = "Journal of Geophysical Research: Space Physics",
year = "2020",
volume = "125",
number = "10",
pages = "e2020JA027773",
month = "Oct",
abstract = "From the analysis of Digisonde data over Brazilian equatorial and
low\‐latitude sites, we investigate the relative importance
of the different parameters driving the generation of rising
bubble\‐type and bottom\‐type spread F (SF)
irregularities. Data for the complete month of October 2001, a
solar maximum epoch (F10.7 = 210), and that of October 2008, an
extended solar minimum period (F10.7 = 70), are analyzed to
examine the SF intensity and occurrence rate as a function of the
evening prereversal vertical drift velocity and the corresponding
F layer heights and the bottom\‐side density gradient.
While the SF at the equatorial site is indicative of both the
bottom\‐side irregularities and rising bubbles, the SF at
the low latitude represents exclusively the latter. Comparison of
the results, from the two epochs, reveals a large decrease in the
intensity and occurrence rate of plasma bubbles, with a decrease
in solar flux. But a notable increase in these characteristics is
observed in the case of bottom\‐side SF. It is found that a
larger (steeper) density gradient of the F layer bottom side that
exists in the low solar flux condition is responsible for an
enhanced Raleigh\‐Taylor instability growth,
counterbalancing a reduction in this rate that may arise from a
smaller prereversal vertical drift and lower layer height that
also characterize the low solar flux condition. Thus, the role of
the bottom\‐side density gradient in the ESF instability
growth has been identified for the first time in terms of its
ability to explain the contrasting irregularity features as
observed during solar flux maximum and minimum years.",
doi = "10.1029/2020JA027773",
url = "http://dx.doi.org/10.1029/2020JA027773",
issn = "2169-9402",
language = "en",
targetfile = "abdu_role.pdf",
urlaccessdate = "20 abr. 2024"
}