Long-term (35 Years) Rainy and Dry Season Characterization in Semiarid Northeastern Brazil
SPARACINO, J.; ARGIBAY, D.S.; ESPINDOLA, G.
REVISTA BRASILEIRA DE METEOROLOGIA
Uncertainties in the timing and quality of rainy season are a threat for food and water security, and also in terms of firevulnerability. Then, understanding features associated to rainfall allows a climate characterization useful for climate andfire risk management. We used rainfall data series (1983-2018) from 15 meteorological stations to characterize thegreatest conservation area of Brazilian-unique seasonally dry tropical forest Caatinga (northeastern Brazil). Accumulatedanomalies in daily series were used to determine onset and end of rainy seasons. We also determined seasonal andannual rainfall (quality) and rain rate, and performed a dry season sub-classification. Results showed greater variabilityfor end dates as compared to onset dates for rainy season. Droughts in the region are becoming more severe. We found asignificant decreasing tendency of 7 mm/year on annual rainfall, of 0.3 mm/day per decade on rain rate, and an increaseof 12 days per decade on consecutive dry days. Dry season length presented a 14-year periodicity and is related withprevious but uncorrelated from posterior rainy season length. The complexity of the rainfall patterns is evidenced by theweak correlation we found between the amount of rainfall and the rainy season length.