Spatiotemporal analysis of extreme climate indices in Nineveh Governorate, northern Iraq: four decades study from 1981 to 2022 using NASA-Power dataset

Understanding the dynamics of climate regimes and related extreme indices is crucial to addressing the influence of climate pattern changes and variability. Despite the significant and complex climate regime of the Nineveh governorate, the long-term dynamics of climate variability remain underexplored. This study investigated the spatial distribution and temporal trends of climate variability with associated extreme indices in the governorate. Using daily data from six stations between 1981 and 2022, six precipitation- and temperature-based extreme climate indices were computed using the RClimDEX package. The results reveal that Nineveh’s climate regime has exhibited significant nonlinear variability and shifts over the past four decades. Specifically, a considerable temperature increase was observed, with a rise of 0.6, 1.01, and 1.48 ℃/decade over the last three decades, relative to 1981–1990. This rate of increase is 3 to 7 times faster than the global average temperature rise of 0.2 ℃/decade. Additionally, precipitation intensity and frequency have significantly decreased, with continuous dry days (CDD) increasing by 19.35% from 125 days/year in 1981–1990 to 155 days/year in 2012–2022. However, the temporal trends in precipitation were weaker than those in temperature. The southern and southeastern regions experienced increased drought conditions, with a shift in concentration from the south to the center. Furthermore, the southeastern region has experienced an increase in temperature and a decrease in precipitation. These findings provide critical insights into the vulnerability of climatic systems in Nineveh and underscore the need for climate change adaptation and mitigation strategies.