A studying of solar-ENSO correlation with southern Brazil tree-ring index (1955?1994)

International audienceSolar activity, volcanic aerosol, El Niño-Southern Oscillation and global temperature anomalies effects on Southern Brazil tree growth rings are presented through multiple linear analysis. Linear correlations were made on annual, 10 year running averages and band pass filter. For annual averages, the correlation coefficients were low, and the 10 years running average correlations the coefficient correlations were much higher. The multiple regression of 2 to 5 year band pass filter indicates that 60% of the variance in tree ring index was explained by volcanic eruptions, Southern Oscillation Index and temperature anomalies. The multiple regression of 10 year running averages indicates that 84% of the variance in tree ring index was explained by solar activity and another time series. These results indicate that the effects of solar activity, volcanic eruptions, ENSO and temperature anomalies on tree rings are better seen on long timescales than volcanic eruption, ENSO and temperature anomaly

Tree-ring width wavelet and spectral analysis of solar variability and climatic effects on a Chilean cypress during the last two and a half millennia

International audienceSpectral and wavelet analysis were performed on a tree ring width time series obtained from a 2500 yr old cypress tree (Fitzroya cupressoides) from Costa del Osorno, Chile. The periods for analysis were selected at 95% confidence level. Both periodicities characteristic of solar activity and climatic variations were found in this tree ring width series. The 11 and 22 years solar cycle periods were present in tree ring data with a confidence level above 98%. This indicates the solar modulation of climatic variations is being recorded by the tree ring grown. However wavelet analysis shows that these are present only sparsely. Short-term variations, between 2-5 years, are also present in tree ring data, and are shown by wavelet maps to be a more permanent characteristic. This time scale is a signature of ENSO events. Long-term variations, above 200 years, are also present in tree ring data. The spectral analysis performed in this work shows that this species has the ability to record solar-ENSO variations that seems to be affecting the local environment of tree growth, and also that this region was influenced by ENSO events at least in the past 2500 yr interval covered by this study

Variability of rainfall and temperature (1912-2008) parameters measured from Santa Maria (29 degrees 41 ' S, 53 degrees 48 ' W) and their connections with ENSO and solar activity

In this work, we analyze the long term variability of rainfall and temperature (1912-2008) of Santa Maria (29 degrees S, 53 degrees W) and its possible connection with natural influences such as solar activity and ENSO. Temperature and rainfall present similar frequencies as revealed by spectral analyses. This analysis shows a large number of short periods between 2-8 years and periods of 11.8-12.3, 19.1-21.0, and 64.3-82.5 years. The cross correlation for rainfall and temperature versus Southern Oscillation Index (SOI) have higher cross-power around 2-8 yr. Rainfall and temperature versus sunspot number (Rz) showed higher cross-power around the 11-yr solar cycle period. A high and continuous cross correlation was observed for Rz-22 yr versus rainfall and temperature. Furthermore, the power between 22-yr solar cycle and meteorological parameters was higher than that obtained with the 11-yr solar cycle, suggesting that the effect of Hale cycle on climate may be stronger than the Schwabe cycle effect. These results indicate that the variability of rainfall and temperature is closely related to the variation of the Southern Oscillation Index and solar activity, and that the El Nino Southern Oscillation and solar activity probably play an important role in the climate system over Southern Brazil. (C) 2011 Elsevier Ltd. All rights reserved.CNPq [APQ470252/2009-0, APQ470455/2010-1, 301033/2009-9, 151609/2009-8]FAPERGS [1013273]FAPESP [2009/02907-8]CAPE

Predicting the solar maximum with the rising rate

The growth rate of solar activity in the early phase of a solar cycle has been known to be well correlated with the subsequent amplitude (solar maximum). It provides very useful information for a new solar cycle as its variation reflects the temporal evolution of the dynamic process of solar magnetic activities from the initial phase to the peak phase of the cycle. The correlation coefficient between the solar maximum (Rmax) and the rising rate ({\beta}a) at {\Delta}m months after the solar minimum (Rmin) is studied and shown to increase as the cycle progresses with an inflection point (r = 0.83) at about {\Delta}m = 20 months. The prediction error of Rmax based on {\beta}a is found within estimation at the 90% level of confidence and the relative prediction error will be less than 20% when {\Delta}m \geq 20. From the above relationship, the current cycle (24) is preliminarily predicted to peak around October 2013 with a size of Rmax =84 \pm 33 at the 90% level of confidence.Comment: 7 pages, 3 figures, accepted for publication in SCIENCE CHINA Physics,Mechanics & Astronom

Prediction of solar activity on the basis of spectral characteristics of sunspot number

Prediction of solar activity strength for solar cycles 23 and 24 is performed on the basis of extrapolation of sunspot number spectral components. Sunspot number data during 1933-1996 periods (solar cycles 17-22) are searched for periodicities by iterative regression. The periods significant at the 95% confidence level were used in a sum of sine series to reconstruct sunspot series, to predict the strength of solar cycles 23 and 24. The maximum peak of solar cycles is adequately predicted (cycle 21: 158&plusmn;13.2 against an observed peak of 155.4; cycle 22: 178<&plusmn;13.2 against 157.6 observed). Solar cycle 23 was predicted to have a peak in 2000 with maximum amplitude of 125&plusmn;13.2, in good agreement with the 119.6 observed. The minimum of solar cycle 23 is predicted to occur around 2007-2008. For solar cycle 24, the maximum is predicted to occur in 2012 (115&plusmn;13.2) or 2013 (117&plusmn;13.2) and this shall be a very weak solar cycle

Continental and coastal marine records of centennial to millennial changes in South American climate since the last glacial maximum

Records of the climatic impacts of the North Atlantic Bond cycles over the subtropical Southern Hemisphere remain scarce, and their mechanism is a topic of active discussion. We present here an alkenone-based reconstructed sea surface temperature (SST) of a sediment core retrieved from the Brazilian Southwestern Tropical Atlantic (SWTA), Rio de Janeiro, together with a sediment SST record from the Cariaco Basin. The sediment cores span the period 2,100 B.P. - 11,100 B.P. Morlet-wavelet analysis detected marked periodic signals of similar to 0.8, similar to 1.7 and similar to 2.2 kyr, very similar and with comparable phases to the hematite-stained-grain time series from the Northern North Atlantic in which the cyclic pattern was recognized as Bond cycles. Our result corroborates the modeled surface ocean anti-phase thermal relation between the North and the South Atlantic. We attribute this behavior to the slowing of the Atlantic Meridional Overturning Circulation. The relative SST warming at Rio de Janeiro and the relative cooling at Cariaco were comparatively more pronounced during the early Holocene (from II to 5 kyr B.P.) than in more recent time

Evidence for cosmic ray modulation in temperature records from\ud the South Atlantic Magnetic Anomaly region

Possible direct or indirect climatic effects related to solar variability and El Niño–Southern Oscillation (ENSO) were investigated in the southern Brazil region by means of the annual mean temperatures from four weather stations 2 degrees of latitude apart over the South Atlantic Magnetic Anomaly (SAMA) region. Four maximum temperature peaks are evident at all stations in 1940, 1958, 1977 and 2002. A spectral analysis indicates the occurrence of periodicities between 2 and 7 yr, most likely associated with ENSO, and periodicities of approximately 11 and 22 yr, normally associated with solar variability. Cross-wavelet analysis indicated that the signal associated with the 22 yr solar magnetic cycle was more persistent in the last decades, while the 11 yr sunspot cycle and ENSO periodicities were intermittent.\ud Phase-angle analysis revealed that temperature variations and the 22 yr solar cycle were in anti-phase near the SAMA center. Results show an indirect indication of possible relationships between the variability of galactic cosmic rays and climate change on a regional scale.CAPESCNPq - APQ 470605/2012-0National Science Foundation - ATM-033952