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The Longest 2020 Meiyu Season Over the Past 60 Years: Subseasonal Perspective and Its Predictions
Author(s) -
Qiao Shaobo,
Chen Dong,
Wang Bin,
Cheung HoNam,
Liu Fei,
Cheng Jianbo,
Tang Shankai,
Zhang Zengping,
Feng Guolin,
Dong Wenjie
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2021gl093596
Subject(s) - trough (economics) , climatology , teleconnection , troposphere , ridge , geology , environmental science , geography , el niño southern oscillation , paleontology , economics , macroeconomics
Abstract The record‐long 2020 Meiyu season since 1961 caused severe floods over the Yangtze and Huaihe River valleys (YHRV). Why the Meiyu duration doubled in 2020 remains a puzzle. We show that the long‐lasting Meiyu can be divided into three stages: advanced‐onset, strong‐persisting, and delayed‐withdrawal. The advanced‐onset was associated with an extremely negative‐phase East Atlantic/West Russia teleconnection. The strong‐persisting was attributed to a positive‐phase Pacific–Japan (PJ) pattern sustained by La Niña's rapid development. The delayed withdrawal was related to the combined effect of a positive PJ pattern and a mid‐troposphere “two ridge–one trough” pattern over Asia. Two subseasonal forecasting systems predicted the positive rainfall anomalies over the YHRV in the first two stages, but not the third stage, which may be associated with poor prediction of the two ridge–one trough pattern. These results highlight the role of subseasonal evolution in extreme climate events.