@Article{PietrellaPFJSKEC:2017:EqSpOc,
author = "Pietrella, M. and Pezzopane, M. and Fagundes, P. R. and Jesus,
Rodolfo de and Supnithi, P. and Klinngam, S. and Ezquer, R. G. and
Cabrera, M. A.",
affiliation = "{Istituto Nazionale di Geofisica e Vulcanologia} and {Istituto
Nazionale di Geofisica e Vulcanologia} and {Universidade do Vale
do Para{\'{\i}}ba (UNIVAP)} and {Instituto Nacional de Pesquisas
Espaciais (INPE)} and {King Mongkut's Institute of Technology
Ladkrabang (KMITL)} and {King Mongkut's Institute of Technology
Ladkrabang (KMITL)} and {Universidad Tecnol{\'o}gica Nacional}
and {Universidad Tecnol{\'o}gica Nacional}",
title = "Equinoctial spread-F occurrence at low latitudes in different
longitude sectors under moderate and high solar activity",
journal = "Journal of Atmospheric and Solar-Terrestrial Physics",
year = "2017",
volume = "164",
pages = "149--162",
month = "Nov.",
keywords = "IonosphereEquatorial ionosphereIonospheric irregularitiesWave
propagation.",
abstract = "A comparative study aimed to investigate the equatorial and
low-latitude spread-F occurrences for moderate solar activity
(MSA) and high solar activity (HSA), was carried out considering
concurrent observations made in some ionospheric stations, which
identify three separate longitudinal sectors: Chiang Mai (CGM;
18.8° N, 98.9° E, mag. Lat. 13.2° N) and Chumphon (CPN; 10.7° N,
99.4° E, mag. Lat. 3.2° N), Thailand; Palmas (PAL; 10.2° S, 311.8°
E, mag. Lat. 0.9° S) and S{\~a}o Jos{\'e} dos Campos (SJC; 23.2°
S, 314.1° E, mag. Lat. 14.0° S), Brazil; Tucum{\'a}n (TUC; 26.9°
S, 294.6° E, mag. Lat. 16.8° S), Argentina. Spread-F phenomena
recorded during the equinoctial months of September and October
2010, March and April 2011, for MSA, March and April 2014,
September and October 2014, for HSA, were classified in two
different modes: range spread-F (RSF) and frequency spread-F
(FSF). The satellite trace (ST) occurrence was also investigated
as possible precursor of spread-F events. When comparing the
results of equatorial (CPN and PAL) and low-latitude (CGM, SJC,
and TUC) stations, some common features independently of the solar
activity emerge: (1) a prevalence of RSF signatures is observed in
the time interval 20:0003:00 LT, while FSF occurrences prevail in
the time interval 03:0006:00 LT; (2) STs are confirmed to be a
possible precursor of RSF occurrences. For HSA, at equatorial
latitudes, spread-F occurrences in the Thai sector (CPN) are
higher than those observed in the Brazilian sector (PAL). When
comparing the results of low-latitude stations of CGM, SJC, and
TUC some unusual aspects characterizing the morphology of spread-F
occurrences emerge: (1) contrary to the Thai and Argentine
sectors, in the Brazilian sector (SJC), RSF and FSF appearances in
September, for HSA, are observed with relatively long persistence
times between about 03:00-06:00 LT and 01:00-03:00 LT
respectively, while balanced RSF and FSF occurrences with short
persistence times are observed for months for MSA; (2) a
prevalence of FSF at CGM during the first half of September for
MSA, never observed in the Brazilian and Argentine areas. During
years of LSA and MSA common morphological aspects are found at CGM
and SJC, that is a predominance of FSF, with the lowest
persistence times characterizing SJC. This suggests that the
low-latitude behaviour of spread-F occurrences, under different
levels of solar activity, at least in the longitude sectors here
analysed, can be to a some extent generalized.",
doi = "10.1016/j.jastp.2017.07.007",
url = "http://dx.doi.org/10.1016/j.jastp.2017.07.007",
issn = "1364-6826",
language = "en",
targetfile = "pietrella_equinoctial.pdf",
urlaccessdate = "16 jun. 2024"
}