Changes of Precipitation Extremes and Persistence Over the Tibetan Plateau Projected by a Convection‐Permitting Model

Abstract

Extreme precipitation has increased over many regions in recent decades, but the simulation and projection remain particularly challenging over complex terrains, such as the Tibetan Plateau (TP). Here, we investigate the future changes in precipitation extremes and persistence over the TP using a kilometer‐scale (3.3 km) convection‐permitting ICON (Icosahedral Nonhydrostatic Weather and Climate Model) model, focusing on comparisons with coarser‐resolution CMIP6 models. Evaluated against station observations, ICON systematically improves the simulation of daily precipitation characteristics, including dry‐day frequency, extreme precipitation and precipitation persistence, reducing root mean square errors by up to ∼10%–94% compared to ERA5 and the CMIP6 ensemble. To project future changes, the pseudo‐global warming (PGW) method is used for ICON, driven by large‐scale climate change signals from the CMIP6 ensemble mean. Both ICON PGW and CMIP6 project qualitatively consistent signals, including increasing extreme precipitation over almost the entire TP and, over the southeastern TP, more dry days and more frequent but shorter precipitation events. Despite consistent signs, ICON PGW suggests a drier southeastern TP than CMIP6, with larger increases in dry days, smaller increases in extreme precipitation and event frequency, and a larger reduction in event duration. The systematic drier future in ICON compared to CMIP6 are linked to projected weakened low‐level summer mean southwesterlies south of the TP, which suppress moisture transport into the interior southeastern TP and thus, reduce both daily and extreme precipitation. As water from southeastern TP affects downstream populations closely, these results provide more reliable projections for future risk assessments.