Distinct Features of Atmospheric Rivers in the Early Versus Late East Asian Summer Monsoon and Their Impacts on Monsoon Rainfall

Chanil Park, Seok Woo Son, Hyemi Kim

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32 Scopus citations


Atmospheric river (AR) and its impact on monsoon rainfall in East Asia are investigated by considering their month-to-month variations during the East Asian summer monsoon (EASM). The AR in the EASM, defined as an anomalously enhanced plume-like water vapor transport, frequently forms over eastern China, Korea and western Japan. However, its characteristics vary from the early (June-July) to the late (August-September) period of the EASM. In the early EASM, AR is typically characterized by a quasi-stationary monsoon southwesterly along the northern boundary of the western North Pacific subtropical high (WNPSH), which is further intensified by a migrating extratropical cyclone in the north. In contrast, the late-EASM AR, which is less frequent than the early EASM AR, is primarily organized by a migrating extratropical cyclone. The quasi-stationary monsoon southwesterly is less influential as the northern boundary of the WNPSH shifts northward, being decoupled from the subtropical ocean. Both the early- and late-EASM ARs contribute substantially to monsoon rainfall, especially to heavy rainfall events. In the early EASM, 35%–70% of total rainfall amount and 60%–80% of heavy rainfall events in eastern China, Korea and western Japan are associated with AR. Although weakened, AR-related rainfall is still significant in the late EASM in Korea and western Japan. These results indicate that AR is a key ingredient of EASM precipitation and its subseasonal variations should be taken into account to better understand and predict AR-related extreme precipitation in East Asia.

Original languageEnglish
Article numbere2020JD033537
JournalJournal of Geophysical Research: Atmospheres
Issue number7
StatePublished - 16 Apr 2021

Bibliographical note

Funding Information:
Constructive and valuable comments from three anonymous reviewers are greatly appreciated. This work was funded by Korea Meteorological Administration Research and Development Program “Enhancement of Convergence Technology of Analysis and Forecast on Severe Weather” under Grant (KMA2018‐00121). Kim was supported by Brain Pool program funded by the Ministry of Science and ICT through the National Research Foundation of Korea 2019H1D3A2A01102234 and by NSF grant AGS‐1652289.

Funding Information:
The catalog of detected ARs is provided in the supporting information. The original version of AR detection code was provided by Bin Guan via https://ucla.box.com/ARcatalog . The development of his AR detection algorithm and databases was supported by NASA. The ERA5 reanalysis data are available at https://cds.climate.copernicus.eu/cdsapp#!/search?type=dataset . The CPC precipitation data are available from https://www.esrl.noaa.gov/psd/data/gridded/data.cpc_hour.html . The GPCP global precipitation product is accessible at https://www.ncdc.noaa.gov/wdcmet/data-access-search-viewer-tools/global-precipitation-climatology-project-gpcp-clearinghouse .

Publisher Copyright:
© 2021. American Geophysical Union. All Rights Reserved.


  • atmospheric river
  • East Asian summer monsoon
  • monsoon rainfall
  • subseasonal climatology
  • synoptic circulation


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