@InProceedings{Abdu:2015:PrWaSt,
author = "Abdu, Mangalathayil Ali",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)}",
title = "Precursor wave structure, polarization electric field and vertical
drift as drivers for equatorial plasma bubble/spread F
development",
year = "2015",
organization = "Annual Meetings Asia Oceania Geosciences Society (AOGS)",
abstract = "The plasma bubble/spread F irregularities of the nighttime
equatorial ionosphere typically develop in the post sunset hours,
and often continue till sunrise. The irregularities develop from
the R-T instability mechanism operating at the bottomside of an F
layer in rapid rise under an enhanced evening prereversal zonal
electric field (PRE). A precursor seed perturbation in electron
density with polarization electric field, to be present at the
steep density gradient region of the F layer bottomside, is an
additional requirement, as per theoretical considerations and
model studies. Recent results from both statistical as well as
case studies bases have supported the presence of such
perturbations in the form of wave structures, likely produced by
upward propagating gravity waves. An important issue concerns the
complementary/competing influences from the PRE and seed
perturbation in the ESF development process. Of particular
interest are the characteristics of the precursor wave structure
in the hours preceding the post sunset ESF development, as
diagnosed by different observational techniques. Analysis of the F
layer heights at specific plasma frequencies as measured by
Digisondes operated at equatorial and low latitude sites,
including magnetic conjugate sites, in Brazil has revealed the
characteristics of precursor wave structure in the form of gravity
wave oscillations and their amplification in the afternoon hours
leading to post sunset ESF development. In this talk we will
present and discuss recent results on the characteristics of the
precursor wave structure as seen by different techniques, and in
particular the observations by Digisondes showing evidence on its
sustenance and amplification in the afternoon hours, supported by
model results, and the relationship to the PRE and post sunset ESF
development.",
conference-location = "Singapore",
conference-year = "2-7 Aug.",
urlaccessdate = "26 abr. 2024"
}