@Article{FrigoAnSiLiPaBa:2018:EfSoAc,
author = "Frigo, Everton and Antonelli, Francesco and Silva, Djeniffer S. S.
da and Lima, Pedro C. M. and Pacca, Igor I. G. and Bageston,
Jos{\'e} Valentin",
affiliation = "{Universidade Federal do Pampa (UNIPAMPA)} and {Universidade
Federal do Pampa (UNIPAMPA)} and {Universidade Federal do Pampa
(UNIPAMPA)} and {Universidade Federal do Pampa (UNIPAMPA)} and
{Universidade de S{\~a}o Paulo (USP)} and {Instituto Nacional de
Pesquisas Espaciais (INPE)}",
title = "Effects of solar activity and galactic cosmic ray cycles on the
modulation of the annual average temperature at two sites in
southern Brazil",
journal = "Annales Geophysicae",
year = "2018",
volume = "36",
number = "1",
pages = "555--564",
month = "Apr.",
keywords = "Meteorology and atmospheric dynamics, climatology.",
abstract = "Quasi-periodic variations in solar activity and galactic cosmic
rays (GCRs) on decadal and bidecadal timescales have been
suggested as a climate forcing mechanism for many regions on
Earth. One of these regions is southern Brazil, where the lowest
values during the last century were observed for the total
geomagnetic field intensity at the Earth's surface. These low
values are due to the passage of the center of the South Atlantic
Magnetic Anomaly (SAMA), which crosses the Brazilian territory
from east to west following a latitude of similar to 26 degrees.
In areas with low geomagnetic intensity, such as the SAMA, the
incidence of GCRs is increased. Consequently, possible climatic
effects related to the GCRs tend to be maximized in this region.
In this work, we investigate the relationship between the -
11-year and similar to 22-year cycles that are related to solar
activity and GCRs and the annual average temperature recorded
between 1936 and 2014 at two weather stations, both located near a
latitude of 26 degrees S but at different longitudes. The first of
these stations (Torres - TOR) is located in the coastal region,
and the other (Irai - IRA) is located in the interior, around 450
km from the Atlantic Ocean. Sunspot data and the solar modulation
potential for cosmic rays were used as proxies for the solar
activity and the GCRs, respectively. Our investigation of the
influence of decadal and bidecadal cycles in temperature data was
carried out using the wavelet transform coherence (WTC) spectrum.
The results indicate that periodicities of 11 years may have
continuously modulated the climate at TOR via a nonlinear
mechanism, while at IRA, the effects of this 11-year modulation
period were intermittent. Four temperature maxima, separated by
around 20 years, were detected in the same years at both weather
stations. These temperature maxima are almost coincident with the
maxima of the odd solar cycles. Furthermore, these maxima occur
after transitions from even to odd solar cycles, that is, after
some years of intense GCR flux. The obtained results offer
indirect mathematical evidence that solar activity and GCR
variations contributed to climatic changes in southern Brazil
during the last century. A comparison of the results obtained for
the two weather stations indicates that the SAMA also contributes
indirectly to these temperature variations. The contribution of
other mechanisms also related to solar activity cannot be
excluded.",
doi = "10.5194/angeo-36-555-2018",
url = "http://dx.doi.org/10.5194/angeo-36-555-2018",
issn = "0992-7689",
language = "en",
targetfile = "frigo_effects.pdf",
urlaccessdate = "02 maio 2024"
}