|
|||||
|
|
Wavelet analysis of a centennial (1895–1994) southern Brazil rainfall series (Pelotas, 31°46′19″S 52°20′ 33″W) |
|
| Authors: | M P Souza Echer E Echer D J Nordemann N R Rigozo A Prestes |
| Institution: | 1. Instituto Nacional de Pesquisas Espaciais (INPE), P.O. Box 515, 12245-970, S?o José dos Campos, S?o Paulo, Brazil 2. Faculdade de Tecnologia Thereza Porto Marques (FAETEC), 12302-320, Jacareí, S?o Paulo, Brazil 3. Universidade Estadual do Rio de Janeiro (UERJ), P.O. Box 524, 20550-013, Rio de Janeiro, Rio de Janeiro, Brazil 4. Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraíba (UNIVAP), Av. Shishima Hifumi, 2911, S?o José dos Campos, S?o Paulo, 12244-000, Brazil |
| Abstract: | In this work we apply the wavelet transform to the Pelotas (southern Brazil) total annual rainfall series (1894–1995). Classical, wavelet and cross-wavelet analyses were performed in the El Niño Southern Oscillation (ENSO), Quasi-Biennial Oscillation (QBO), sunspot number (Rz) and Pelotas rainfall time series. Classical spectral analysis for Pelotas has shown a large number of short periods – between 2.2–5.6 years (yr) and periods at 8.9, 11.7 and 24.9 yr. Further, we have found that the Pelotas rainfall wavelet spectrum shows the most significant periodicities around 2–8 yr, but they have an intermittent character. Cross-wavelet spectrum showed that: rainfall and QBO series are correlated at 2–3 yr (QBO) scales and this cross-power is continuous along the time series interval; rainfall and SOI have higher cross-power around 4–8 yr, but this signal is sporadic; rainfall and sunspot number (Rz) showed higher cross-power around the 11-yr solar cycle period, but this cross-power is sporadically high and low; finally, the rainfall cross-spectrum with the double sunspot number (Rz22) revealed a high cross-power around 20–22 yr which is more persistent in duration, compared to the 11-yr period. These wavelet results are compared with classical spectral analysis and with previous work results. We concluded that the phenomenon that influences most of Pelotas rainfall variability is ENSO, but only a minor part of the variance (～30%) can be described by a simple multi-linear dependence on solar/ENSO/QBO phenomena, this result could imply that non-linear coupling among sun and internal climatic variability (QBO, ENSO) has an important role in the local/regional climate variations. |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ | |