@Article{BarrosBPMMBBM:2017:EfMiTe,
author = "Barros, Figueiredo Cosme Alexandre Oliveira and Buriti, Ricardo A.
and Paulino, Igo and Meriwether, John W. and Makela, Jonathan J.
and Batista, Inez Staciarini and Barros, Diego and Medeiros,
Amauri F.",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and
{Universidade Federal de Campina Grande (UFCG)} and {Universidade
Federal de Campina Grande (UFCG)} and {Clemson University} and
{University of Illinois at Urbana-Champaign} and {Instituto
Nacional de Pesquisas Espaciais (INPE)} and {Instituto Nacional de
Pesquisas Espaciais (INPE)} and {Universidade Federal de Campina
Grande (UFCG)}",
title = "Effects of the midnight temperature maximum observed in the
thermosphere-ionosphere over the northeast of Brazil",
journal = "Annales Geophysicae",
year = "2017",
volume = "35",
number = "4",
pages = "953--963",
month = "Aug.",
keywords = "Ionosphere, equatorial ionosphere, ionosphere-atmosphere
interactions, meteorology and atmospheric dynamics, thermospheric
dynamics.",
abstract = "The midnight temperature maximum (MTM) has been observed in the
lower thermosphere by two Fabry-Perot interferometers (FPIs) at
Sao Joao do Cariri (7.4 degrees S, 36.5 degrees W) and Cajazeiras
(6.9 degrees S, 38.6 degrees W) during 2011, when the solar
activity was moderate and the solar flux was between 90 and 155
SFU (1 SFU = 10(-22) W m(-2) Hz(-1)). The MTM is studied in detail
using measurements of neutral temperature, wind and airglow
relative intensity of OI630.0 nm (referred to as OI6300), and
ionospheric parameters, such as virtual height (h'F), the peak
height of the F2 region (hmF2), and critical frequency of the F
region (foF2), which were measured by a Digisonde instrument (DPS)
at Eusebio (3.9 degrees S, 38.4 degrees W; geomagnetic coordinates
7.31 degrees S, 32.40 degrees E for 2011). The MTM peak was
observed mostly along the year, except in May, June, and August.
The amplitudes of the MTM varied from 64 +/- 46K in April up to
144 +/- 48K in October. The monthly temperature average showed a
phase shift in the MTM peak around 0.25 h in September to 2.5 h in
December before midnight. On the other hand, in February, March,
and April the MTM peak occurred around midnight. International
Reference Ionosphere 2012 (IRI-2012) model was compared to the
neutral temperature observations and the IRI-2012 model failed in
reproducing the MTM peaks. The zonal component of neutral wind
flowed eastward the whole night; regardless of the month and the
magnitude of the zonal wind, it was typically within the range of
50 to 150 m s(-1) during the early evening. The meridional
component of the neutral wind changed its direction over the
months: from November to February, the meridional wind in the
early evening flowed equatorward with a magnitude between 25 and
100 m s(-1); in contrast, during the winter months, the meridional
wind flowed to the pole within the range of 0 to 50 m s(-1). Our
results indicate that the reversal (changes in equator to poleward
flow) or abatement of the meridional winds is an important factor
in the MTM generation. From February to April and from September
to December, the h'F and the hmF2 showed an increase around
18:00-20:00 LT within a range between 300 and 550 km and reached a
minimal height of about 200-300 km close to midnight; then the
layer rose again by about 40 km or, sometimes, remained at
constant height. Furthermore, during the winter months, the h'F
and hmF2 showed a different behavior; the signature of the
pre-reversal enhancement did not appear as in other months and the
heights did not exceed 260 and 350 km. Our observation indicated
that the midnight collapse of the F region was a consequence of
the MTM in the meridional wind that was reflected in the height of
the F region. Lastly, the behavior of the OI6300 showed, from
February to April and from September to December, an increase in
intensity around midnight or 1 h before, which was associated with
the MTM, whereas, from May to August, the relative intensity was
more intense in the early evening and decayed during the night.",
doi = "10.5194/angeo-35-953-2017",
url = "http://dx.doi.org/10.5194/angeo-35-953-2017",
issn = "0992-7689",
language = "en",
targetfile = "figueiredo_effects.pdf",
urlaccessdate = "19 mar. 2024"
}