DÃÆóris Veleda, Raul Montagne, Moacyr Araujo, Giuliano Pereira, Pedro TyaquiÃÆçÃÆã, Carlos Noriega, Francis Lacerda
The Sub-middle São Francisco Valley (SMSF), Northeast Brazil, is known for its great potential for viticulture, as it is one of the few regions in the world with two to three harvests per year. Results presented here establish the influence of remote Sea Surface Temperature (SST) on the rainfall variability and wine chemical compounds in the SMSF. Cross-correlation analyses show that the rainfall in the SMSF is negatively correlated with the SST at the North Tropical Atlantic, and positively correlated with the SST at Southwestern Atlantic. Cross-wavelet analyses identify that, in addition to the annual signal, intermittent signals in rainfall at the SMSF respond to remote influences of the SST with 3-4 months of periodicity at interannual timescales (~36-month band). Coherence analyses identify that the SST in Southwestern Atlantic affects the rainfall in the SMSF at the 3-4-month periodicity band. Principal Component Analysis indicated different influences between wet and dry meteorological seasons on the chemical wine samples produced at SMSF. Extreme rainfalls observed during 2009, are linked to northward displacement of the South Atlantic Convergence Zone, when strong rainfall and high relative humidity at SMSF contributed to reduce Free Sulfur Dioxide (FSO2) in grapes. During dry seasons the northward displacement of Intertropical Convergence Zone (ITCZ) is correlated to lower rainfall and relative humidity (RH) in SMSF region, resulting in higher Sulfur Dioxide (TSO2, FSO2), alcohol and higher acidity (VOL. AC) wines.
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