Linking the North Atlantic Oscillation to rainfall variability and dynamics in Algeria through GIS and wavelet theory

This study presents a regionalized analysis of the relationship between the North Atlantic Oscillation (NAO) and rainfall across 69 monthly rainfall stations in northeastern Algeria for the period 1970-2007. The approach integrates Cross-Wavelet Transform (XWT) and Wavelet Coherence Transform (WCT), complemented by Hierarchical Ascending Classification (HAC) and Geographic information system (GIS), to address dissimilarity issues and to identify coherent spatiotemporal patterns between the NAO and regional rainfall variability. Results indicate strong and persistent coherence in the northern region, particularly within the 4-16 and 16-32-month bands. The central region displays moderate and less stable coherence, whereas the southern region reveals weak and intermittent associations. The findings emphasize the superior reliability of WCT over XWT, due to its enhanced ability to suppress spurious correlations. This analysis corroborates existing evidence of NAO's significant influence on Mediterranean climate variability and demonstrates its potential to improve rainfall forecasting, particularly when integrated with artificial intelligence techniques. Continuous monitoring of NAO phases is recommended to strengthen drought early warning systems and adaptive water resource management strategies in Algeria.