A Lagrangian View of Moisture Transport Related to the Heavy Rainfall of July 2020 in Japan: Importance of the Moistening Over the Subtropical Regions

N. Zhao; A. Manda; X. Guo; K. Kikuchi; T. Nasuno; M. Nakano; Y. Zhang; B. Wang

doi:10.1029/2020GL091441

A Lagrangian View of Moisture Transport Related to the Heavy Rainfall of July 2020 in Japan: Importance of the Moistening Over the Subtropical Regions

N. Zhao
, A. Manda
, X. Guo
, K. Kikuchi
, T. Nasuno
, M. Nakano
, Y. Zhang
, B. Wang

Research output: Contribution to journal › Article › peer-review

46 Scopus citations

Abstract

The transport and accumulation of moisture played an essential role in the extremely heavy rainfall of July 2020 in Japan. To better understand this event in terms of moisture sources and transport routes, backward particle trajectory analysis was conducted. We found two major moisture sources: transport from the tropics and uptake from the subtropics. A narrow moisture channel was found along the edge of the western Pacific Subtropical High (WPSH), transporting the moisture to the Baiu front. However, most moisture from the tropics was lost due to precipitation, and their contributions were reduced to about 15%. In contrast, the subtropical regions contributed over 80% moisture via evaporation and lower tropospheric convection. Among those regions, the western Pacific contributed the most (>33%). This study highlights the role of WPSH in moisture transport and demonstrated the importance of moisture uptake during transport.

Original language	English
Article number	e2020GL091441
Journal	Geophysical Research Letters
Volume	48
Issue number	5
DOIs	https://doi.org/10.1029/2020GL091441
State	Published - Mar 2021
Externally published	Yes

Funding

The authors are grateful for the quick analysis by Youichi Kamae (University of Tsukuba) and quick report by JMA on the 20HR. We thank two anonymous reviewers for their constructive and fruitful comments. This work was partially supported by JSPS KAKENHI (JP19H05697 and JP17H02958) and the Collaborative Research Program (2020S2‐6) of RIAM, Kyushu University. This work is also supported by the regular annual budget of authors' institute (JAMSTEC) from the MEXT of Japan. The authors are grateful for the quick analysis by Youichi Kamae (University of Tsukuba) and quick report by JMA on the 20HR. We thank two anonymous reviewers for their constructive and fruitful comments. This work was partially supported by JSPS KAKENHI (JP19H05697 and JP17H02958) and the Collaborative Research Program (2020S2-6) of RIAM, Kyushu University. This work is also supported by the regular annual budget of authors' institute (JAMSTEC) from the MEXT of Japan.

Keywords

Lagrangian trajectories
atmospheric river
heavy rain
moisture transport

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10.1029/2020GL091441

Cite this

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title = "A Lagrangian View of Moisture Transport Related to the Heavy Rainfall of July 2020 in Japan: Importance of the Moistening Over the Subtropical Regions",

abstract = "The transport and accumulation of moisture played an essential role in the extremely heavy rainfall of July 2020 in Japan. To better understand this event in terms of moisture sources and transport routes, backward particle trajectory analysis was conducted. We found two major moisture sources: transport from the tropics and uptake from the subtropics. A narrow moisture channel was found along the edge of the western Pacific Subtropical High (WPSH), transporting the moisture to the Baiu front. However, most moisture from the tropics was lost due to precipitation, and their contributions were reduced to about 15\%. In contrast, the subtropical regions contributed over 80\% moisture via evaporation and lower tropospheric convection. Among those regions, the western Pacific contributed the most (>33\%). This study highlights the role of WPSH in moisture transport and demonstrated the importance of moisture uptake during transport.",

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AU - Zhao, N.

AU - Manda, A.

AU - Guo, X.

AU - Kikuchi, K.

AU - Nasuno, T.

AU - Nakano, M.

AU - Zhang, Y.

AU - Wang, B.

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AB - The transport and accumulation of moisture played an essential role in the extremely heavy rainfall of July 2020 in Japan. To better understand this event in terms of moisture sources and transport routes, backward particle trajectory analysis was conducted. We found two major moisture sources: transport from the tropics and uptake from the subtropics. A narrow moisture channel was found along the edge of the western Pacific Subtropical High (WPSH), transporting the moisture to the Baiu front. However, most moisture from the tropics was lost due to precipitation, and their contributions were reduced to about 15%. In contrast, the subtropical regions contributed over 80% moisture via evaporation and lower tropospheric convection. Among those regions, the western Pacific contributed the most (>33%). This study highlights the role of WPSH in moisture transport and demonstrated the importance of moisture uptake during transport.

KW - Lagrangian trajectories

KW - atmospheric river

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DO - 10.1029/2020GL091441

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A Lagrangian View of Moisture Transport Related to the Heavy Rainfall of July 2020 in Japan: Importance of the Moistening Over the Subtropical Regions

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Keywords

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