Changes in rainfall patterns in southern Brazil over 1961–2020 period detected by rain gauge data

Abstract

AbstractLong‐term instrumental climate records are a major source of data for historical trends and extreme event analysis. Time series analysis of several rain gauges shows that the mid‐latitudes of Brazil experienced an increase in both annual and extreme rainfall over the last 60 years (1961–2020). The annual time series shows a significant upward trend, while changes in the frequency and intensity of heavy rainfall indicate a shortening of the recurrence interval for extreme precipitation events. In support of these results, the standardized precipitation index (SPI) also shows a positive trend for rainfall anomalies. Thus, the flood risk is higher at present than a few decades ago, while drought intensity is lower for both short and long monthly intervals used for the SPI calculation. The 60‐year instrumental rainfall data for southern Brazil shows that the amount of rainfall and changes in intensity could be higher than climate projections from models based on a broader spatial scale.