Padrões de variabilidade multiescalar na temperatura da superfície do mar no Atlântico tropical e norte e seus efeitos nas chuvas da América do sul

Abstract

The variability of sea surface temperature (SST) in the North Atlantic Ocean (ATN) during the 1901-2009 period was investigated using empirical orthogonal functions (FSO), spectral analysis and linear correlation. The results of the FSO analysis showed two modes of variability revealed a multiscale basis, and the mode 1 (mode 2) is narrower at the ATN region (Atlantic Nino) and comprising 22% (11%) of variability total anomalies in this region. This multiscale aspect indicated that a breakdown of modes at different scales of temporal variability could reveal the understanding of their interactions with climate indices. It was shown that the mode 1 (mode 2), reveals itself as oscillations on scales of 50-70 years, 30-40 years, 20-30 years, 3-5 years, 8-16 years (40-60 years and 8 -16 years), and that its variability is controlled by climatic indices active in preferred timescales. To the scale of 50-70 years, coherence and phase analysis between climatic indices and the Principal Component series mode 1 (CP01), shows greater respect to the Index of Multidecenal Atlantic Oscillation (OMA), indicating that at this scale variability of the TSM ATN is strongly maintained by local influences. Especially in the range of 30-40 years the remote effects appear to act more strongly to the variability in ocean temperature. For the ranges of 20-30 years and 8-16 years, the local effects of the OMA and the North Atlantic Oscillation (NAO) as well as remote as the Pacific Decadal Oscillation (PDO) and El Niño Southern Oscillation (ENSO) seem set the variability of SST, and the same goes for the annual scale. To Principal Component mode 2 (CP02), coherence analysis and wavelet phase showed that in the range of 40-60 years, the pattern is related to the ODP, while for the 8-16 year range is related variability NAO and ENSO on this same scale. The effects on rainfall, the WCO in positive phase in the range of 50-70 years old and is positively (negatively) for regions of central and southern Amazon (northeast, south and west of AS, for the range of 20-30 years, the anomalies are negative (positive) in the northeast and west of Brazil (in regions spread north, central and southern AS). On the scale of 8-16anos their positive contribution is restricted to the far northern portion of the AS and south Northeast Brazil, while for the range of 3-5 years, reducing the signs (increase) of rainfall are restricted to tropical portion (south of the Northeast and Brazil). Exclusively associated with performances of OAN operating in lower frequency (30 -40anos), signs of positive (negative) are seen throughout the tropical zone (central and southeastern SA). For the other scales, the positive signs in Brazil's northeastern portion are always noticed, while negative signals They are more confined in the central and southeastern part of Brazil, and especially in the range of 20-30anos, while for mode 2 and in the range of 8-16 years, its operations favors positive signs scattered throughout AS. The contribution of the ODP, the scale is restricted 20-30anos (40-60anos) and associated with mode 1 (mode 2), acting on opposite signs and reduction (increase) in considerable region of AS. It is attributed to ENSO, a structure dipole anomalies in rainfall, with negative signals (positive) to the north (south) SA, while for the 30-40 years range signals are reduced, ENSO is an importance on integrating rainfall for this temporal variability of scale. It is noteworthy that due FSO methodology used, signs of inverse correlations rainfall for both modes and all climate indices are seen when they are considered negative phase periods of the series. However, it was noted that not only the nature of the dominant events prevail in terms of meanings impacts on the continent, but the persistence of the signals over time gained a significant role in integrating the final results. It was confirmed that the variability of rains in AS are explained by the SSTA's tropical, but multiscale context favored more results 9 accurate their respective areas of performances. Restricted to the Atlantic, has set itself an importance on the mode 1 (mode2) for drought events (full) in the Amazon, once a standard hot (cold) in the ATN and North (Atlantic Niño), suggests a reduction standard (increase) in rains in the central portion and east (north and west) of the Amazon basin in interdecenais and interannual scales (multidecenais) time, which explains the asymmetry in years of extreme events observed during the series of 109 years.