@Article{SripathiAbduPatrGhod:2018:UnGeLo,
author = "Sripathi, S. and Abdu, Mangalathayil Ali and Patra, A. K. and
Ghodpage, R. N.",
affiliation = "{Indian Institute of Geomagnetism} and {Instituto Nacional de
Pesquisas Espaciais (INPE)} and National Atmospheric Research
Laboratory, ISRO and {Indian Institute of Geomagnetism}",
title = "Unusual Generation of Localized EPB in the Dawn SectorTriggered by
a Moderate Geomagnetic Storm",
journal = "Journal of Geophysical Research: Space Physics",
year = "2018",
volume = "123",
number = "11",
pages = "9697--9710",
month = "Nov.",
abstract = "An interesting piece of observation related to the equatorial
plasma bubble (EPB) that is triggered by a geomagnetic storm at
dawn sector on 4-5 February 2011 is presented. The storm activity
was initiated at 17 UT when interplanetary magnetic field (IMF) Bz
turned southward and the Dst index started decreasing (accompanied
by AE intensifications) attaining its minimum at -70 nT. The IMF
Bz presented large fluctuations marked by southward/northward
transitions at slow and rapid rates and eventually returning to
normal in the morning of 5 February. Observations from the very
high frequency radar located at Gadanki, an off-equatorial
station; an all-sky imager located at Kolhapur, a low-latitude
station; and an ionosonde at Tirunelveli, an equatorial station,
are analyzed to study the impact of this storm on the postmidnight
to presunrise equatorial spread F. The results demonstrate that
EPB irregularities can be generated by penetration electric field
during what can be characterized as a moderate storm event. In
contrast to prevailing belief, the present results show that
EPB/equatorial spread F can be generated by undershielding
electric field in the dawn sector, caused by an unusually delayed
polarity reversal of the penetration electric field. The results
further reveal oscillatory behavior in the height of F layer
topside irregularities in association with IMF Bz oscillations.
Observation of radar echoes from nighttime E layer irregularity
structures and their Doppler velocities representing the
penetration electric field polarity and intensity are also a
notable finding of this paper.",
doi = "10.1029/2018JA025642",
url = "http://dx.doi.org/10.1029/2018JA025642",
issn = "2169-9402",
language = "en",
targetfile = "sripathi_unusual.pdf",
urlaccessdate = "27 abr. 2024"
}