Potential impact of precipitation temporal structure on meteorological drought and vegetation condition: A case study on Qinghai-Tibet Plateau

Qinghai-Tibet Plateau (QTP). The Qinghai-Tibet Plateau (QTP) is sensitive to climate change and ecologically fragile. Researches on precipitation over the QTP mainly focus on quantity and frequency, overlooking its temporal distribution. However, subtle changes in precipitation can significantly impact the natural environment and lead to natural disasters. This work primarily focuses on the response of meteorological drought and vegetation growth to the precipitation temporal structure. The precipitation temporal structure is quantified from the perspectives of the contribution of heavy precipitation (concentration index, CI) and the temporal distribution of total precipitation (standardized variability index, SVI) using CPC unified gauge-based analysis of global daily precipitation over 1982–2022. The CI and SVI exhibit a significant decreasing trend across almost the entire QTP, which means the temporal distribution of precipitation has become more "even" within a year. Meteorological drought was analyzed using the sc-PDSI and SPEI-12 indices. Both indices indicate that drought has intensified in both the humid regions (southeastern QTP) and arid regions (northern QTP). However, in the transition zone between dry and humid areas, drought conditions have shown signs of alleviation. Analysis of the vegetation indicates a greening trend across the QTP, particularly in the northeastern regions. CI is more superior than the SVI in characterizing vegetation growth, especially in the transitional zones between bare land and grassland where precipitation is sparse. The findings provide a scientific basis for vegetation restoration and drought risk management on the QTP. • Precipitation structure is quantified by contribution of heavy precipitation and temporal distribution of total amount. • Droughts have intensified in both humid and arid regions, whereas in the transitional zones, conditions have alleviated. • The Standardized Variation Index ( SVI ) outperforms the concentration index ( CI ) in delineating meteorological drought. • In areas where vegetation is present, uniform precipitation favors the growth of vegetation.