Diurnal cycle of summer precipitation in the Eastern Tarim Basin and surrounding mountains using the WRF-NJU model

Study region Eastern Tarim Basin and its surrounding mountains (Bayingol Mongolian Autonomous Prefecture, Xinjiang, China), with focus on the core Eastern Tarim Basin (ETB), Southern slope of Tianshan Mountains (STM), and North slope of Altun-Kunlun Mountains (NAKM). Study focus Utilizing high-resolution WRF-NJU model data, multi-source observations, and reanalysis datasets, this study systematically analyses the diurnal cycle of precipitation (DCP) in the region. Emphasis is placed on the spatiotemporal heterogeneity of precipitation amount (PA), frequency (PF), intensity (PI), and peak timing. New hydrological insights for the region WRF-NJU successfully reproduces DCP, confirming its reliability for high-resolution simulations in arid regions. PA and PF show single afternoon peaks, while PI exhibits dual peaks at dawn and dusk. Mountain precipitation peaks mainly during 14–16 LST, whereas basin precipitation displays nocturnal dominance. PF is the principal driver of diurnal precipitation variability across the region. High coefficients of variation (CV) reveal extreme PF fluctuations in the basin. Overlapping CV-PA and CV-PI values in mountains indicate persistent rainfall elevating hydrological hazards. Precipitation peaks exhibit elevational delays (10–22 LST), transitioning from bimodal to unimodal afternoon patterns above 4500 m. Forests, water bodies, and grasslands show dominant afternoon precipitation, while impervious surfaces and croplands peak pre-dawn, demonstrating urbanization and agricultural impacts on local DCP. This work provides critical scientific foundations for understanding spatiotemporal precipitation mechanisms and water-resource risk management in arid zones.