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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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  • Ning Zhao,
  • Atsuyoshi Manda,
  • Xiaojun Guo,
  • Kazuyoshi Kikuchi,
  • Tomoe Nasuno,
  • Masuo Nakano,
  • Yuanxin Zhang,
  • Bin Wang
Ning Zhao
Japan Agency for Marine-Earth Science and Technology

Corresponding Author:zhaoning@jamstec.go.jp

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Atsuyoshi Manda
Mie University
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Xiaojun Guo
University of Hawaii
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Kazuyoshi Kikuchi
International Pacific Research Center, Universith of Hawaii
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Tomoe Nasuno
Frontier Reserach Center for Global Change
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Masuo Nakano
Japan Agency for Marine-Earth Science and Technology
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Yuanxin Zhang
Tokyu University of Marine Science and Techology
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Bin Wang
Hohai University
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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 also demonstrated the importance of the moisture uptake during the transport.
16 Mar 2021Published in Geophysical Research Letters volume 48 issue 5. 10.1029/2020GL091441