Abstract The increase in Galactic Cosmic Rays (GCR) flux intensity induces the Condensation Nuclei (CN) production, which intensifies rainfall occurrences. Then, the objective of this study was to ...analyze the rainfall distribution in the NEB and the impact of GCR flux on extreme rainfall events occurred in July 1998 in Natal/RN, Brazil. We used historical rainfall, Sea Surface Temperature (SST) and GCR flux data for Natal/RN. We used R software for statistical analysis. The results indicate that the GCR flux is important for intensifying extremes rainfall occurrences. This fact is observed when analyzing the relationship between rainfall greater than 10 mm and GCR flux above 6,390 counts/min. Pearson correlation coefficient between rainfall and GCR flux was 0.94 (p-value = 0.0005) and SST was -0.76 (p-value = 0.0263), both statistically significant. The rate between GCR flux and rainfall was +2.87 mm/count/min, while the rate between SST and rainfall was -7.91 mm/°C. The variance proportion explained by regression was 94.41%, with relative importance degree corresponding to 62.0% for GCR flux and 32.4% for SST, respectively. The results show that GCR flux had a greater contribution to extreme rainfall occurrence in the metropolitan region of Natal/RN and it is important in climatological studies.
•Sunspot Cycle 25 is predicted using Warped Gaussian Process regression.•The model outputs a full distribution, used to assess the forecasting uncertainty.•Cycle 25 is expected to peak in 2024, with ...a value of 110 sunspot number units.
Solar cycle prediction is a key activity in space weather research. Several techniques have been employed in recent decades in order to try to forecast the next sunspot-cycle maxima and time. In this work, the Gaussian process, a machine-learning technique, is used to make a prediction for the solar cycle 25 based on the annual sunspot number 2.0 data from 1700 to 2018. A variation known as Warped Gaussian process is employed in order to deal with the non-negativity constraint and asymmetrical data distribution. Tests using holdout data yielded a root mean square error of 10.0 within 5 years and 25.0–35.0 within 10 years. Simulations using the predictive distribution were performed to account for the uncertainty in the prediction. Cycle 25 is expected to last from 2019 to 2029, with a peak sunspot number about 117 (110 by the median) occurring most likely in 2024. Thus our method predicts that solar Cycle 25 will be weaker than previous ones, implying a continuing trend of declining solar activity as observed in the past two cycles.
Earth magnetic field variations at secular scales and at hundred quilometers have internal origin at the outer core. The most important feature associated with this internal field is the South ...Atlantic Magnetic Anomaly (SAMA), which covers the South America and it is characterized by the lowest total field intensity at the surface. Here, we investigate the geomagnetic field variations in Santa Maria (Brazil) over the past 3 ka. Results indicate that the intensities observed in Santa Maria are the lowest of the geomagnetic field over the past 3 ka. The consequences of these field features could be the increase in the electrically charged particles reaching the low Earth atmosphere that may generate problems in the communications systems or climate changes.
We present the first high resolution, approximately ∼4 years sample spacing, precipitation record from northeastern Brazil (hereafter referred to as ‘Nordeste’) covering the last ∼3000 yrs from ...230Th‐dated stalagmites oxygen isotope records. Our record shows abrupt fluctuations in rainfall tied to variations in the intensity of the South American summer monsoon (SASM), including the periods corresponding to the Little Ice Age (LIA), the Medieval Climate Anomaly (MCA) and an event around 2800 yr B.P. Unlike other monsoon records in southern tropical South America, dry conditions prevailed during the LIA in the Nordeste. Our record suggests that the region is currently undergoing drought conditions that are unprecedented over the past 3 millennia, rivaled only by the LIA period. Using spectral, wavelet and cross‐wavelet analyses we show that changes in SASM activity in the region are mainly associated with variations of the Atlantic Multidecadal Oscillation (AMO) and to a lesser degree caused by fluctuations in tropical Pacific SST. Our record also shows a distinct periodicity around 210 years, which has been linked to solar variability.
Key Points
The SAMSs activity on multidecadal timescale
Climate during LIA, MCA and CWP and their possible forcings
Abrupt events of precipitation in NE Brazil during last 3k
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 ∼ 26∘. 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
∼ 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∘ S but at different
longitudes. The first of these stations (Torres – TOR) is located in the
coastal region, and the other (Iraí – 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. Keywords. Meteorology and atmospheric dynamics (climatology)
The Earth’s rotation can change as a result of several internal and external processes, each of which is at a different timescale. Here, we present some possible connections between the Earth’s ...rotation variations and the geomagnetic reversal frequency rates over the past 120 Myr. In addition, we show the possible relationship between the geomagnetic field reversal frequency and the δ18O oscillations. Because the latter reflects the glacial and interglacial periods, we hypothesize that it can be used as a possible indicator to explain the length of day (LOD) variations and consequently the reversal field frequency over the past 510 Myr. Therefore, our analysis suggests that the relationships between the geomagnetic reversal frequency rates and the Earth’s rotation changes during the Phanerozoic. However, more reversal data are required for periods before the KRS to strengthen the perspective of using the geomagnetic reversal data as a marker for the LOD variations through geological times.
An analysis of geomagnetic storm variations and the count rate of cosmic ray muons recorded at the Brazilian Southern Space Observatory -OES/CRS/INPE-MCT, in São Martinho da Serra, RS during the ...month of November 2004, is presented in this paper. The geomagnetic measurements are done by a three component low noise fluxgate magnetometer and the count rates of cosmic ray muons are recorded by a Muon Scintilator Telescope - MST, both instruments installed at the Observatory. The fluxgate magnetometer measures variations in the three orthogonal components of Earth magnetic field, H (North-South), D (East-West) and Z (Vertical), with data sampling rate of 0.5 Hz. The Muon Scintilator Telescope records hourly count rates. The arrival of a solar disturbance can be identified by observing the decrease in the muon count rate. The goal of this work is to describe the physical morphology and phenomenology observed during the geomagnetic storm of November 2004, using the H component of the geomagnetic field and vertical channel V of the multi-directional muon detector in South of Brazil.
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