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Abstract 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.
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An Expanded Investigation of Atmospheric Rivers in the Southern Appalachian Mountains and Their Connection to Landslides
Previous examination of rain gauge observations over a five-year period at high elevations within a river basin of the southern Appalachian Mountains showed that half of the extreme (upper 2.5%) rainfall events were associated with an atmospheric river (AR). Of these extreme events having an AR association, over 73% were linked to a societal hazard at downstream locations in eastern Tennessee and western North Carolina. Our analysis in this study was expanded to investigate AR effects in the southern Appalachian Mountains on two river basins, located 60 km apart, and examine their influence on extreme rainfall, periods of elevated precipitation and landslide events over two time periods, the ‘recent’ and ‘distant’ past. Results showed that slightly more than half of the extreme rainfall events were directly attributable to an AR in both river basins. However, there was disagreement on individual ARs influencing extreme rainfall events in each basin, seemingly a reflection of its proximity to the Blue Ridge Escarpment and the localized terrain lining the river basin boundary. Days having at least one landslide occurring in western North Carolina were found to be correlated with long periods of elevated precipitation, which often also corresponded to the influence of ARs and extreme rainfall events.
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- Award ID(s):
- 1637522
- PAR ID:
- 10129723
- Date Published:
- Journal Name:
- Atmosphere
- Volume:
- 10
- Issue:
- 2
- ISSN:
- 2073-4433
- Page Range / eLocation ID:
- 71
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/atmos10020071
