Analysis of Monsoonal Rainfall Patterns and Anomalies using NASA POWER Data and the Mann-Kendall Test in Northeast India

Abstract

Understanding the variability of monsoonal rainfall is vital for assessing climatic patterns and their implications on agriculture and water resources in Northeast India—a region characterized by complex topography and high rainfall variability. This study investigates long-term trends and anomalies in rainfall across Northeast India using NASA POWER (DAV) point-based precipitation data. The Mann–Kendall (MK) test, ITA and Sen’s slope estimator were applied to detect and quantify monotonic trends and sub-trends in rainfall time series, while rainfall anomalies were computed to assess monsoonal rainfall variability. Results indicate spatial variation, with increasing monsoon rainfall trends observed in the northeastern states as per the statistical analysis and ITA plot. While the monsoonal rainfall anomalies shows both wet and dry periods amongst the states indicating the variation of rainfall patterns in the region. These findings can further enhance understanding of regional rainfall dynamics and provide a scientific basis for improving climate adaptation and water resource management in Northeast India.