Understanding orographic precipitation pattern in Arizona: Implications for climate change

Study area: This study focused on Arizona, encompassing diverse landscapes such as high-elevation mountains, low-elevation deserts, and intermediate plateaus. Precipitation data from four representative stations, Baldy, Maricopa, Safford, and Workman Creek, were analyzed to reflect the region’s climatic and topographic variability. Study Focus: The study investigated precipitation patterns, particularly orographic influences, over the past three decades and projected future changes under climate change scenarios. Statistical and machine learning methods were utilized, including Self-Organizing Maps (SOM) for clustering, the Mann-Kendall test for trend analysis, and a Convolutional Neural Network and Long Short-term Memory (CNN-LSTM) model for downscaling. Mutual information (MI) analysis assessed relationships between precipitation and climatic predictors. Projections under Representative Concentration Pathway (RCP)4.5 and RCP8.5 explored impacts of varying emission pathways. New hydrological insights for the region: Analysis of the past 33 years showed no statistically significant trends in total annual precipitation across Arizona. Nonetheless, noticeable shifts in mean precipitation and seasonal patterns were observed at several locations, which may indicate emerging signals of climate variability. Climate model projections under RCP8.5 suggested a general decline in precipitation, especially in mountainous regions, along with reduced interannual variability. In contrast, desert regions such as Maricopa may experience increased variability. These findings highlight the importance of localized water resource planning and adaptive strategies to address potential climate-induced hydrological changes in Arizona.