Quantitative Analysis of Moisture Budget in the Lifecycle of Consecutive Atmospheric River Events Affecting East Asia

Atmospheric rivers (ARs) efficiently transport moisture from tropical and/or subtropical regions to middle and high latitudes, serving not only as the most important global poleward moisture transport belts but also as one of the primary causes of extreme precipitation and flooding in many parts of the world. Research on ARs in East Asia started relatively late; however, due to the region’s unique climatic characteristics, the manifestations of ARs differ from those in regions such as North America. In recent years, studying the lifecycle characteristics of consecutive AR events has become increasingly important. Nevertheless, on a climatic timescale, the moisture origins and transport processes during consecutive AR events in East Asia remain poorly understood, which is critical for understanding the genesis and sustenance of such events. In this study, the ERA5 reanalysis data from 1980 to 2024 were used to extract a dataset of consecutive AR events that made landfall in East Asia during this period, based on which the basic climatic characteristics of AR lifecycles were analyzed. Furthermore, this research focuses on the moisture sources and transport processes of ARs, employing an extended dynamic moisture recycling model specifically designed for tracking moisture in consecutive ARs to conduct a detailed quantitative analysis of the moisture budget during the lifecycle of ARs affecting East Asia. The findings reveal that ARs impacting East Asia typically originate from the Bay of Bengal to southwestern China and dissipate over the Yangtze–Huai River region, the Korean Peninsula, and Japan. The moisture contributing to ARs in East Asia mainly originates from the Indian Ocean, the Western Pacific, and high-latitude Eurasian regions, with the most significant contributions coming from the Arabian Sea, the Bay of Bengal, the Western Pacific, and terrestrial areas in eastern China. Notably, the moisture contribution from land areas in East Asia, particularly South China, is crucial for sustaining and transporting moisture during the AR lifecycle, highlighting the reliance of consecutive AR events on moisture transport from mid- and even high-latitude regions.