@InProceedings{PimentaCaAmSaBiFaGo:2008:ReAsTh,
author = "Pimenta, Alexandre Alvares and Candido, Claudia Maria Nicoli and
Amorim, Danielle Cristina de Morais and Sahai, Yogeshwar and
Bittencourt, Jos{\'e} Augusto and Fagundes, P. R. and Gobbi,
Delano",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto
Nacional de Pesquisas Espaciais (INPE)} and {Instituto Nacional de
Pesquisas Espaciais (INPE)} and {Instituto Nacional de Pesquisas
Espaciais (INPE)} and {Instituto Nacional de Pesquisas Espaciais
(INPE)} and {Universidade do Vale do Para{\'{\i}}ba (Univap)}
and {Instituto Nacional de Pesquisas Espaciais (INPE)}",
title = "Relevant aspects of thermospheric dark band structures observed by
ground-based optical and radio techniques over the Brazilian
low-latitude sector under different solar activity conditions",
booktitle = "Proceedings...",
year = "2008",
organization = "International Symposium on Equatorial Aeronomy, 12.",
abstract = "Using ground-based measurements we investigate the occurrence of
dark band structures in the OI 630 nm nightglow emission all-sky
images in the Brazilian low latitudes region during the periods
from January 1990 to December 1990 and from January 2000 to
December 2000 (high solar activity period; average 10.7 cm solar
cycle flux > 180x10\−22Wm\−2Hz\−1 ), January
1995 to December 1996 (low solar activity period; average 10.7cm
solar cycle flux < 90x10\−22Wm\−2Hz\−1 ) and
from January 1997 to December 1999 (ascending solar activity
period; average 10.7 cm solar cycle flux
from130x10\−22Wm\−2Hz\−1
to170x10\−22Wm\−2Hz\−1 ). The OI 630 nm
images obtained during these periods show thermospheric Dark Band
Structures (DBS) in low latitudes region propagating from
southeast to northwest. These dark patches moved with average
speed of about 80-250 m/s at an altitude of 220-300 km, which is
the typical altitude range of the OI 630.0 nm airglow emission.
Also, digisonde observations registered abrupt increases in both
the F-layer peak height (hmF2) and base height (hF) when the low
intensity band passed over Cachoeira Paulista. During the period
studied a strong solar cycle and seasonal variations were noticed
in the DBS. Only during low solar activity period (LSA) and
ascending solar activity period (ASA) the DBS occurrences were
observed in the OI630 nm nightglow emission all-sky images. It
should be pointed out that these thermospheric/ionospheric events
are not related to geomagnetic disturbed conditions. In this paper
we present important features from these set of observations in
the nighttime thermosphere/ionosphere under different solar
activity conditions. A possible mechanism for generation of these
dark band structures is presented.",
conference-location = "Crete, Greece",
conference-year = "18-24 may",
label = "self-archiving-INPE-MCTIC-GOV-BR",
language = "en",
targetfile = "pimenta_relevant.pdf",
urlaccessdate = "05 maio 2024"
}