Long-term variation of precipitation indices in Ceará State, Northeast Brazil



The state of Ceará is a semiarid region in north-eastern Brazil, having a high spatial and temporal variability of precipitation, which poses challenges for water resources management. The objective of this study is to describe and analyse the long-term variation of monthly precipitation indices and their relation to sea surface temperature (SST) anomalies. Data from 55 weather stations in the state of Ceará from 1974 to 2009 was analysed. In general, a decreasing tendency in monthly precipitation was observed over almost all the state of Ceará. The results point to a tendency for dry months to become dryer and to a decrease in precipitation intensity. SST anomalies from October to March correlate with precipitation indices from January to April, showing decreasing lag times towards the end of the wet season. The most influential SST anomalies locations are Niño 1+2, Niño 3, Niño 3.4 and Global Tropics.