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Fig. 7.13 Comparison of sea surface temperature (SST) in the tropical Pacific, represented by the
Niño-3 temperature reconstruction (Mann et al. 2000 ; red line ), and precipitation variations in the
Bolivian Altiplano, inferred from Caquella-Soniquera composite chronology ( blue line ) lagged 1
year ( t + 1), and significant correlated oscillatory modes extracted by singular spectrum analysis
(SSA). Common oscillatory modes have periods of ( b ) 9-10 years, ( c ) 4 years, and ( d ) 3 years.
Percentages of the original variance contributed by each of Niño-3 and the Bolivian waveforms are
indicated in parentheses at the upper and lower left corners of the figures, respectively. In the lower
right corners, r is the Pearson's correlation coefficient between Niño-3 and the Bolivian composite
series
These spectral analyses basically reaffirm the existence of common oscillatory
modes in tropical Pacific SST and precipitation-sensitive chronologies in subtropical
North and South America, but also reveal changes in the stability of teleconnec-
tions over time. Indeed, moving correlations (using a 50-year window) between
the precipitation-sensitive chronologies from South America and the El Niño-3 SST
reconstruction revealed such changes in the temporal stability of the teleconnections
(Fig. 7.14 ) . Significant correlations occur for most of the sub-periods compared;
however, correlation coefficients were not statistically significant during the second
part of the eighteenth century between the Niño-3 SST and both the Bolivian and
 
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