利用小波分析研究巴西北部和东北部气候指数序列中的多十年周期
Multidecadal Cycles Study in the Climate Indexes Series Using Wavelet Analysis in North/Northeast Brazil
AI总结：
本文利用小波分析研究了巴西北部和东北部气候指数序列中的多十年周期，发现32、64、128和256个月的周期，对应约2.66至21.33年，与太阳活动和气候变异相关。
摘要：
本研究利用R软件中的WaveletComp和biwavelet包，对最近80年的气候指数时间序列进行小波分析，发现主要周期为32、64、128和256个月，对应约2.66、5.33、10.66和21.33年。这些周期从1933年1月到2016年9月，共993个月（82.75年），表征了十到多十年的变异性。这些多十年周期（约10.66和21.33年）可能与太阳活动和海洋-大气系统中的气候变异性有关。对巴西北部和东北部五个城市的降雨数据进行了分析，发现这些数据与SOI、PDO和太阳黑子序列中观察到的十到多十年周期相似。
英文摘要：
This study investigates the climatic index time series over the most recent 80 years, using monthly mean values from the Pacific Decadal Oscillation Index (PDO), Southern Oscillation Index (SOI), and monthly solar activity represented by sunspot numbers (MS), obtained from the National Weather Service Climate Prediction Center and the World Data Center SILSO, Royal Observatory of Belgium, Brussels. The statistical software R was used with the \texttt{WaveletComp} package to generate Morlet wavelet power spectra, and bivariate cross-wavelet analysis using the \texttt{biwavelet} package. The results show predominant cycles with variability scales of 32, 64, 128, and 256 months, corresponding approximately to 2.66, 5.33, 10.66, and 21.33 years. These frequencies are observed in the period from January 1933 to September 2016, totaling 993 months (82.75 years), characterizing decadal and multidecadal variability. These multidecadal cycles (of the order of 10.66 and 21.33 years) suggest a possible association with solar activity variability and climate variability in the ocean-atmosphere system. Rainfall data from January 1951 to September 2017 were analyzed for Belém, São Luiz, Fortaleza, Natal, and Fernando de Noronha, forming a north to northeast Brazilian transect. These series show similarity with the decadal and multidecadal cycles observed in the SOI, PDO, and sunspot series.
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