Long-term (35 Years) Rainy and Dry Season Characterization in Semiarid Northeastern Brazil

Abstract

Uncertainties in the timing and quality of rainy season are a threat for food and water security, and also in terms of fire vulnerability. Then, understanding features associated to rainfall allows a climate characterization useful for climate and fire risk management. We used rainfall data series (1983-2018) from 15 meteorological stations to characterize the greatest conservation area of Brazilian-unique seasonally dry tropical forest Caatinga (northeastern Brazil). Accumulated anomalies in daily series were used to determine onset and end of rainy seasons. We also determined seasonal and annual rainfall (quality) and rain rate, and performed a dry season sub-classification. Results showed greater variability for end dates as compared to onset dates for rainy season. Droughts in the region are becoming more severe. We found a significant decreasing tendency of 7 mm/year on annual rainfall, of 0.3 mm/day per decade on rain rate, and an increase of 12 days per decade on consecutive dry days. Dry season length presented a 14-year periodicity and is related with previous but uncorrelated from posterior rainy season length. The complexity of the rainfall patterns is evidenced by the weak correlation we found between the amount of rainfall and the rainy season length.

Could Forage Palm and Stone Barrier Be as Effective as Native Vegetation in Controlling Runoff and Erosion in the Brazilian Semiarid Region?

“…Sparacino et al [2], in their study in semi-arid northeastern Brazil, observed a strong seasonality of rainfall with 90% of rainfall events occurring during the rainy season, which on average lasts for 152 days. However, the onset and end dates of the rainy season also shows high interannual variability.…”

“…The predominant vegetation is the hypoxerophilous Caatinga [18]. The basin's drainage area is 12.56 km 2 , with an average slope of 17.92% (Wavy Relief) and elevations ranging from 600 to 1019 m, with a runoff concentration time of 58.71 min [12].…”

Variabilidad climática en la planificación hídrica de la cuenca del río Cravo Sur (Casanare, Colombia)

“…) pertenecientes al sistema terrestre dentro de un área en estudio. Usualmente se considera que 30 años de datos es un período suficiente para definir el clima de una región, en el que las variables físicas siguen patrones definidos año a año (Beltrán y Díaz, 2020;Sparacino et al, 2021). Así, la variabilidad climática corresponde a períodos de tiempo relativamente cortos, y se diferencia del cambio climático, porque los valores de las variables climatológicas como temperatura y precipitación entre otras, pueden ser comparadas con un valor normal (Álzate et al, 2015).…”