Solar activity and El-Niño signals observed in Brazil and Chile tree ring records

This work presents a review of the results obtained by research on solar-terrestrial relationships developed by analyzing tree growth rings from Southern Brazil and Chile. These studies were performed using harmonic spectral and wavelet analysis. The time interval covered by the samples is 200 yr for Brazil and 2500 yr for Chile. It was observed that sample trees from Southern Brazil are showing a ring growth response favorable to the increase of solar activity. Although periodicities associated to the 11 yr solar cycle were observed in sample trees from Chile, this relation was not so favorable as in Brazilian trees. However, Chile tree ring widths have a much better response to low period, which indicates that they are more adequate to study El Niño events environmental variations than those from Brazil.