Major moisture source patterns for extreme precipitation events over the Chinese Loess Plateau

Abstract

AbstractExtreme precipitation (EP) has significant hydrological and environmental influences on the Chinese Loess Plateau (CLP) during the rainy season (June–September). In this study, we analysed the moisture sources for the EP events over the CLP during the rainy season. Three major moisture source patterns were identified through analysing the moisture source variability across the EP events with a newly developed method combining the Lagrangian moisture diagnostic and a clustering algorithm. South China and North China were determined as the most critical moisture source regions for the EP events over the CLP. The three moisture source patterns corresponded to three EP types, including the CLP‐A type with a high contribution from North China (23.55%, the relative moisture contribution) and a relatively low contribution from South China (13.77%), and the CLP‐B and CLP‐C types, which had limited contributions (10.64% and 13.28%) from North China in common, and exhibited moderately high (19.30%) and extremely high (30.59%) contributions from South China, respectively. The moisture transport pathways for the three EP types were quantitatively analysed in detail. The favourable circulation patterns for the three EP types were further illustrated to reveal the atmospheric conditions for the spatial variations in moisture source patterns. In addition, this study provides a new strategy to analyse the moisture source variability, especially when it is difficult to find an easily manipulated criterion to classify the precipitation events.